Before undertaking any hike in the Grand Canyon, it is extremely important to note that a hike of any length is not to be taken lightly, even on routinely maintained and patrolled trails which have been constructed with visitor safety in mind.  Grand Canyon National Park offers a variety of hiking options reachable from the South Rim which are managed according to backcountry use area.  Each use area has a limited overnight capacity based upon the size of the area, the number of suitable and available campsites, its ecological sensitivity, its management zoning, and its use history.  To camp below the rim in a backcountry use area you must obtain a backcountry permit.  Of the trails that I will describe in this field trip (1A), there are two main rim-to-river trails within the “Corridor” use area, including the Bright Angel Trail and South Kaibab Trail, although the short Plateau Point and River Trails which connect with them also fall in this category.  The Corridor Zone is recommended for hikers without previous Grand Canyon experience.  The trails are well groomed and make for pleasant hiking, they receive routine maintenance and are consistently patrolled by rangers, and they boost purified water stations, toilets, signage, emergency phones, and ranger stations.  The Hermit Trail, also accessed from a South Rim trailhead near Hermits Rest, the initial stretch of the Boucher Trail and short connecting trail to Dripping Springs (only accessed from the Hermit Trail), and the Tonto Trail, which can only be accessed at either end from the Hermit Trail or Bright Angel Trail, occur within “Threshold” use areas. Trails with a threshold designation are recommended for hikers with previous Grand Canyon experience.  These trails only receive occasional maintenance (if severely damaged by a landslide for example) and are irregularly patrolled by backcountry rangers.  The main Boucher Trail and the part of the Tonto Trail connecting campsites at Boucher and Hermit Creeks, fall within the Primitive Zone.  Trails and routes within “Primitive” use areas are not maintained or patrolled and are recommended only for highly experience Grand Canyon hikers with proven route-finding skills.  Hiking on trails in Primitive use areas is not recommended during the summer because of high temperatures and/or because they lack reliable water sources.

It is, of course, best to hike during the fall or spring hiking seasons when precipitation is least likely and temperatures within the canyon are generally cool, but not cold.  The park service recommends that you “take appropriate precautions depending on seasonal variations in trail [i.e. weather] conditions.”  During the winter season, the upper portions of many trails can be dangerously icy because the wintertime sun never reaches into the confines of the side canyons where most trails are found, and ice can remain on the trails long after a snowstorm passes.  In-step crampons and hiking poles are recommended.  The relative tranquility of weather in summer can be very misleading.  From May to September, it is critical that hikers (especially backpackers) have the discipline to begin hiking well before dawn, or in the late afternoon and early evening; heat exhaustion, over-exposure, and dehydration are constant threats!  The park service strongly recommends that “hikers should plan on reaching either their destination or a place where they might take a shaded siesta before 10 in the morning (average descent time from rim to river is between 4 and 6 hours).” Similarly, when ascending from river-level during hot weather it is important to reach the relatively shaded canyon head areas by 8-10 in the morning.  It is definitely not a good idea to hike between noon and 4pm.  I would add that unless you are greatly accustomed to the rigors of the canyon, it is shear folly to attempt a rim-to-river-to-rim hike in a single day (I caution against out and back hikes of any kind that are more than 6-8 miles in length, unless you start and end early and are a speedy, and in shape hiker).  So let’s get hiking!

Boucher and Dripping Springs Trails (Tr1A.1)

The Boucher (pronounced Boo-shay) Trail was the creation of Louis D. Boucher, the “hermit” of the Hermit Creek basin and Boucher Canyon. Boucher maintained seasonal residences at Dripping Spring and in lower Boucher Creek and lived in the area for two decades. According to the National Park Service, Boucher was “well known and socially active within the South Rim community during the latter part of the 19th century”, although most people knew him as a hermit because he choose to live alone.  Boucher’s original trail into Boucher Canyon, called the “Silver Bell”, descended from the rim above Dripping Spring. Today, the location of that trailhead is an obscure spot no longer accessible by vehicle, so very few hikers follow the original switchbacks down to the spring, although they are generally intact, although the history buff may find the effort appealing.  For the purposes of this trail description, the author has chosen the modern trailhead for the Dripping Spring Trail and the Boucher Trail, which starts at the intersection with the Hermit Trail at about one and three-quarters of a mile, near the top of the Esplanade Sandstone.  Thus, you’ll have to descend the upper portion of the Hermit Trail (Tr1A.3) to reach this junction, and from there, it is just over a mile to the beginning of the Boucher Trail, or about a mile and a half to Dripping Spring.  The Boucher Trail does provide access to a secluded and beautiful part of the Grand Canyon brimming with unique and readily observed geological features, but the price of admission is steep. This trail challenges even experienced canyon hikers with two tough, tedious traverses linked together by incredible descents that will have your knees begging for mercy, and for extra fun, there is even a small section of exposed hand and toe climbing required.

The park service states that “the Boucher Trail is arguably the most difficult and demanding of the south side trails” given the overall poor condition of the trail and its steepness, especially in the Supai Group and Redwall Limestone sections.  To find the Hermit trailhead, depart from the park’s free shuttle service at Hermit’s Rest, the last stop on the Red Route, and walk a short distance along the rim to the west (Stop #10 on Map 1A.3 and Map 1A.1.1).  Day-hikers heading to Dripping Spring can walk over to the Village Route Transfer Station to hop aboard the Red Route (Stop #1 on Map 1A.2) from their vehicles parked at the Backcountry Information Center, from nearby rim hotels, or from the Hermits Route Transfer Station on the Blue Route (Stop #6 on Map 1A.2).  However, backpackers may find the parking area at the trailhead a much easier marshalling point.  According to the park service, “a numerical code is required to open the gate giving access to the Hermit Road at the Hermit Transfer”.  The keypad used to enter this code is mounted on the steel post that supports the swinging arm of the gate.  From April through October, “backpackers with a valid backcountry permit for the Hermit Trail can drive 8 miles west along Hermit Road to Hermits Rest, then continue beyond the end of the pavement on the dirt road ¼ mile to the trailhead.”, but note that during the winter the Hermit Road is open to all vehicles and no code is required for access.

The Hermit Trail is the best entry route for any backpacking excursions into Boucher Canyon. If you plan to camp below the rim, the park service indicates that the Boucher Trail is contained within an “at-large” use area, so camping is permitted anywhere (although please use previously established sites if at all possible).  Pleasant camping can be found along the trail where it rounds below Yuma Point at about six and a quarter miles in and on the saddle in the ridge extending south from Whites Butte at about seven and a quarter miles in, although both locations are dry sites (plan to bring extra water). The Yuma Point campsite affords gorgeous sunrises and sunsets and is the better option. The main campsites in Boucher Canyon occur along Boucher Creek and also at the Colorado River at about nine and a half and ten and a half miles in, respectively.   The hike down the Hermit Trail reaches the Dripping Spring/Boucher junction in about one and three quarters of a mile, and from there, it is just over a mile to the Dripping Spring spur trail (another half mile to reach the spring itself). Dripping Spring makes for a great day hiking option, the geology along the way is marvelous; but start early to avoid returning to the rim in the afternoon heat.  For experienced hikers, the campsites on Boucher Creek can be reached in a long day, trekking all the way to the river campsite is only for the most fit or the foolish.  Personally, why rush?  Hiking to Boucher Creek and back leaves you looking at the same scenery twice (not that there’s anything wrong with that).  However, I recommend a counterclockwise loop hike down the Hermit Trail, over to Boucher Creek on the Tonto Trail, and a return to the rim on the Boucher Trail, with camps at Hermit Creek, Boucher Creek, and Yuma Point.  It’s a shorter descent to Hermit Creek camp, and I find that ascending from Boucher Creek to Yuma Point much easier than the opposite.

After descending to the lower end of the upper Hermit Creek basin on the Hermit Trail (see Tr1A.3 for a description), a marked trail junction can be found at 1.76 miles (Map 1A.1.1).  By this point, you have dropped through the Kaibab Limestone, Toroweap Formation, Coconino Sandstone, and much of the Hermit Formation.  This juncture will serve as the “trailhead” for the Boucher (and Dripping Spring) Trail.  Leave the Hermit Trail here by taking the left-hand (west) fork marked for Dripping Spring; this trail gently undulates near the contact between the Hermit Formation and the underlying Esplanade Sandstone along the western wall of Hermit Canyon, eventually passing around Yuma Point before dropping into Travertine Canyon.  For now, follow the narrow trail for about a mile as it swings in and out of two embayments cut back into the Coconino headwall on its way to the deep recess of the Dripping Spring basin forming the western head of the Hermit drainage.  At roughly 0.19 miles (Map 1A.1.1), the trail climbs to a low ridge separating upper Hermit basin from the two small amphitheaters carved into the Coconino Sandstone, and offers striking views of the cliff-forming Esplanade Sandstone, the top most member of the Supai Group (Figure 1A.1.1).  Dripping Spring basin can be seen in the background. When you reach the rib of sandstone separating the two Coconino alcoves near 0.62 miles (Map 1A.1.1), be sure to take in the spectacular view down the axis of Hermit Canyon.  As with many of the Grand Canyon’s tributaries, Hermit Creek has carved its scenic corridor along an ancient fault, the Hermit Fault, which has weakened the layers of rock and made them more susceptible to erosion.  At about 0.88 miles (Map 1A.1.1), as the trail rounds through the second embayment and begins to climb into Dripping Spring basin, be on the lookout for trailside brick red outcrops of Hermit Formation displaying ripple marks, mud cracks, and vertically oriented clam burrows (Figure 1A.1.2).  These structures, and the unit’s sandstone and mudrock layers, attest to its origins in shallow marine to low lying coastal depositional environments.

Figure 1A.1.1.  The Esplanade Sandstone is well exposed in upper Hermit Canyon; its thick, resistant layers form a distinctive cliff at the base of the Hermit Formation’s mudstone slopes.

Figure 1A.1.2.  Sedimentary structures in the Hermit Formation belay its depositional origins on an ancient coastline; (A) a slab of sandstone displays mudcracks and vertically oriented clam burrows, and (B) a ripple-marked bedding surface on a siltstone.

Your route reaches the trail junction between the Dripping Spring Trail and Boucher Trail at 1.12 miles (Map 1A.1.1).  Here, the Boucher Trail departs to the right, in a northerly direction continuing the long “Supai Traverse” on the rim of the Esplanade Sandstone, a trail feature common to many rim-to-river routes in the Grand Canyon.  Before tackling the main event however, let’s take a short side trip to Dripping Spring.  A quick hike of 0.44 miles brings you to the spring which has formed at the contact between the Coconino Sandstone and underlying Hermit Formation (Figure 1A.1.3), a minor diversion well worth your time.  Springs often form in such locations, where groundwater percolating downward through relatively porous rocks (in this case the predominantly limestone and sandstone layers of the Kaibab, Toroweap, and Coconino) enters an impermeable unit (the mudrocks of the Hermit) and is forced to flow laterally.  The groundwater emerges at a “spring” when the impermeable rock layer intersects with the ground surface.  The contact between rock units is easily observed in the wall behind the spring where whitish sandstone overlies reddish mudstone (Figure 1A.1.4a); spectacular sandstone-filled desiccation cracks in the Hermit accent the contact (Figure 1A.1.4b).  These enormous mudcracks seen in vertical cross-section indicate the abrupt change in climate and depositional environments between the relatively wet conditions of the Hermit and the extreme aridity of the Coconino.  The sand dunes of the Coconino advanced so rapidly over the coastal muds of the Hermit, the deeply penetrating desiccation cracks where filled with sand and preserved in perpetuity within the rock record.

Figure 1A.1.3.  Dripping Spring occupies the northwest wall at the head of Dripping Spring basin, formed at the contact between the Coconino and Hermit where rocks permeable to groundwater flow overlie impermeable material.

Figure 1A.1.4.  The abrupt contact between the Coconino Sandstone and Hermit Formation is easily distinguished in the rock face behind Dripping Spring (A); here, the contact is brought into sharp focus by the presence of Coconino sand-filled mega-scale desiccation cracks in the mudstone of the Hermit (B).

Perhaps a brief discussion of the significance of springs such as Dripping Spring to the overall formation of the Grand Canyon is in order.  Note the position of the spring relative to the Paleozoic stratigraphy, and to the geomorphology of its headwall basin and the larger Hermit Canyon.  Hermit Canyon is deeply recessed into the South Rim, and its two main tributaries, upper Hermit basin and Dripping Spring basin are even more deeply recessed.  Dripping Spring, and others like it, occurs at the point of greatest retreat from the Colorado River.  Groundwater flow from springs aids a geomorphic process known as scarp retreat, a process that begins with stream channel dissection through rock layers of various coherency and strength.  Weak layers consisting of mudrocks like the Hermit Formation are prone to weathering and erosion and tend to quickly retreat away from the downcutting channel, forming slopes and a broad valley; whereas strong layers consisting of cemented, interlocking grains of limestone and sandstone sediment like the Kaibab and Coconino tend to hang around, forming cliffs and a narrow incised valley.  While coherent rocks are resistant to weathering and erosion due to their composition, they are often brittle and contain an array of criss-crossing joints or fractures caused by tectonic forces or the release of overlying pressure during overall landscape denudation. These joints act as conduits for downward movement of water originating as precipitation on the plateaus surrounding the Grand Canyon.

When groundwater seeping through jointed, porous rocks such as limestone and sandstone encounters impermeable shale, it flows laterally along the zone of contact until emerging at a spring where the ground surface intersects the contact.  The discharge of water concentrated at the spring erodes the underlying weak mudstones through a process called groundwater sapping, eventually producing an overhang of more resistant rock above (Figure 1A.1.4a).  Gradual widening of the overhang reduces support for the overlying rock, and when vertically oriented joints are eventually exposed, the entire block may give way gradually, in slabby rockfalls, or more spectacularly in massive landslides to produce a new cliff face at the position of the spring.  Of course, slope retreat does not require groundwater sapping, but the sapping process enhances the natural tendency for strong, cliff-forming rock units to be undercut by more rapid retreat of underlying weaker, slope-forming layers.  Over time, the entire staircase of slope and cliff-forming layers retreats from the incising stream, albeit faster where sapping occurs (such as at the head of Hermit Canyon).

Once you have returned to the junction with the Boucher Trail (1.90 miles since leaving the Hermit Trail; Map 1A.1.1), turn left (north) and begin your lengthy Esplanade traverse.  The route quickly crosses the main, east-flowing dry wash draining Dripping Spring basin, then trends northeasterly to a low ridge at 2.32 miles (Map 1A.1.1) separating the main wash from a small south-flowing tributary.  The ridge crest offers a good view of the upper Paleozoic rock sequence with a nicely exposed section of the Coconino-Hermit contact and the red beds of the Hermit Formation (Figure 1A.1.5); this slope will be your constant companion for the next two miles.  The route ahead crosses numerous small, steep washes and intervening ridges, and is made tiresome by complicated rockslides from the Coconino cliff above; although it is easy enough to follow.  By now, however, the trail will be in the sun because of its east facing exposure, probably its most difficult feature to overcome.  Blocks of well-weathered Kaibab Limestone are not uncommon, tumbling down from the distant cliffs above.  Look for fossils in relief on the surface of these blocks, and the chert nodules they contain often display nice sponge spicules (Figure 1A.1.6).  Hermit Creek camp and the Tapeats Sandstone narrows below it come into view on your right beginning about midway through this traverse.  Be sure to look behind you every so often, not only to gage your travel, but the views back into upper Hermit basin are beautiful (Figure 1A.1.7).  The location marked at 2.83 miles is only one of many possible views (Map 1A.1.1).  And geologically speaking, these views afford excellent opportunities to discern the Hermit Fault in the canyon’s eastern wall where the distinctive notch eroded into the upper Paleozoic units parallels the trend of the canyon.

Figure 1A.1.5.  The upper Paleozoic stratigraphy is nicely exposed in the western wall of Hermit Canyon.

Figure 1A.1.6.  Blocks of Kaibab Limestone litter the trail; keep a sharp eye pealed for fossils such these fine sponge spicules contained in the unit’s chert nodules.

Figure 1A.1.7.  The receding view to your rear gages your progress and offers scenic beauty; note the notch in the Kaibab Limestone and Toroweap Formation to the left (east) of the canyon, this marks the position of the northeast trending Hermit Fault.

Finally, after a trek that seems longer than it actually is, the spectacular Esplanade slickrock camp below Yuma Point is reached at 4.44 miles (Map 1A.1.1).  If you have come down from Hermits Rest, you have made more than six miles of rough trail; rewarding yourself with an overnight stay here is not unreasonable.  Early risers have been known to make this memorable destination the turn-around point in long day hike, but I would recommend an overnight because the dual sunset and sunrise are quite impressive.  Besides, the three miles remaining to Boucher Creek camp is by far the toughest portion of this trail.

This location may also be the finest upper canyon camp on the South Rim, made so by its soaring vistas of varicolored cliffs and slopes, mesas, buttes, and towers, up, down, and across the canyon (Figure 1A.1.8a).  Watch the marvelous interplay between clouds, sky, rock, and shadow from the shady overhang below a thick layer of resistant sandstone in Esplanade.  Your expansive view encompasses Vishnu Temple upcanyon to the north and east, and swings all the way around to Powell Plateau downcanyon to the north and west.  Classic seasonal “water pots” weathered by frost action and chemical alteration into the surface of the Esplanade Sandstone are an added bonus (Figure 1A.1.8b); and they may even contain drinkable water if you come in the spring or fall.  I give you fair warning though; this area is directly below the park’s  “Dragon Flight Corridor” which can mean the incessant sound of helicopter noise during the daytime; however, to the park service’s credit, a two-hour dawn and dusk flight curfew will allow a well-planned hike to be enjoyed in silence.  For seasoned canyon backpackers that have trekked the Hermit Trail, one additional feature of this campsite is worth mentioning.  From the tip of the overlook, a huge section of the Hermit Trail can be traced out, especially the section that drops through the Cathedral Stairs (Figure 1A.1.9).  Be sure to look across Hermit Creek to the top of the Cathedral Stairs and try to identify the trace of the Hermit Fault.  The upper right corner of Figure 1A.1.9 shows the graben and collapse features in the red and gray rocks of Supai Group and Redwall Limestone where a splay of the fault passes from northeast to southwest, dropping the rocks to the west of the fault downward relative to those east of the fault.

Figure 1A.1.8.  The Boucher Trail campsite below Yuma Point offers spectacular Grand Canyon vistas such as this directly across the canyon (A); and the Esplanade Sandstone on which it sits is pockmarked with semicircular depressions formed by physical and chemical weathering processes that often contain drinkable water in the spring and fall, or shortly following summer rains (B).

Figure 1A.1.9.  The Hermit Trail’s infamous Cathedral Stairs as viewed from the Yuma Point campsite on the Boucher Trail.

Regardless of your plans, the Boucher Trail continues on perhaps its most level section across the flat Esplanade as it rounds the corner below Yuma Point and heads into the upper end of Travertine Canyon. At about 5.15 miles (Map 1A.1.1), the route drops precipitously down the Supai Group’s characteristically ledgy slope nearly 1000 feet toward the next level section on the top of the Redwall Limestone.  Initially, a break in the Esplanade cliff requires a brief encounter with hand and toe climbing which can be intimidating, and it is tough going throughout the rapid Supai descent. The trail here is steep, narrow, and covered in ball bearing-like pebbles that have a propensity for twisting ankles, so take your time!  Personally, having hiked this trail in both directions, I prefer taking it on the ascent (my pack is lighter by this time, my body has been toughened by several days on the trail, and my knees thank me for the relief from a bone-crunching descent).  As you navigate this section of trail, paying attention to odd zigzags through cliff bands in the Supai, do not overlook the significance of its geology.  The breakdown slope, such as it is here, has formed along the southern end of the Muav Fault, a zone of related normal faults which can be traced diagonally down Travertine Canyon from southeast to northwest and across the ridge separating this canyon from Boucher Canyon to the west (Figure 1A.1.10).  A good vantage point to view the fault occurs near a left-hand switchback in the trail at 5.38 miles (Map 1A.1.1).  The fault passes through the saddle in the ridge just south of Whites Butte and is well exposed in the massive Redwall Limestone cliff that forms the western wall of lower Travertine Canyon.  The Muav Fault is one of several major NW-SE trending faults exposed in the Grand Canyon that extend across the Colorado Plateau in this region.  Extensional faulting was first active in the late Proterozoic associated with the breakup of the Rodinian supercontinent to the west, although the faults were reactivated by compression during the Late Cretaceous to Early Tertiary Laramide Orogeny, and are now active again due to Basin and Range extension.

Figure 1A.1.10.  A fault traverses diagonally SE-NW down Travertine Canyon and passes through the ridge separating it from Boucher Canyon to the west.

The route descends to the Redwall rim of Travertine Canyon, dropping quickly downward through landslide debris to a point near the Redwall cliff where you cross the upper dry wash of Travertine Canyon floored by water-sculpted limestone, smoothed and polished to a marble-like finish.  Crossing to the west side of the drainage, follow the trail north on fairly level terrain, passing a notch in the Redwall near 6.30 miles (Map 1A.1.1) that marks the location of the Muav Fault.  Turn around here and look back at the canyon’s headwall (Figure 1A.1.11).  It is a relatively easy matter to align the notch you are standing near to the rent in the Redwall cliff at the canyon head; this is the trace of the fault.  To the right side of the headwall, you can see the elongated debris apron from the landslide you recently descended.  From there, the trail makes a beeline across the open, grassy saddle between Cocopa Point and Whites Butte to the top of a gully at 6.50 miles (Map 1A.1.1) that plummets through the Redwall Limestone southwest of Whites Butte.  Careful observation indicates that the gully is aligned with the exposed fault on the opposite side of the ridge you have just traversed; erosion has exploited the zone of weakness in the Redwall created by fault-related fracturing of the rock (Figure 1A.1.12).  You are now only about two miles from the campsites and permanent water on Boucher Creek, but the 1,800 foot descent ahead is a real dozy.

Figure 1A.1.11.  The headwall of Travertine Canyon and your route in or out on the Boucher Trail; the trail descends abruptly through the fault-controlled gully left of the sunlight promontory separating the two headwall drainages, crosses to the landslide debris filling the gully to the right, and descends the elongated debris apron to the Redwall rim.

Figure 1A.1.12.  The Boucher Trail’s precipitous descent through the Redwall Limestone begins at the head of a fault-controlled gully eroded into the west side of the ridge extending between Cocopa Point and Whites Butte.

If you didn’t camp at Yuma Point, this last descent to Boucher Creek is nothing less than brutal, at best, a physical beating in classic Grand Canyon style that surpasses many other so called “bad” sections on South Rim trails.  To lighten your load though, focus on the geology, it’s superb!  After passing through a few switchbacks in the upper Redwall, the trail passes onto an interesting breccia in the bottom of the gully; this is your first exposure to travertine deposits, a common feature in this part of the Grand Canyon (recall Travertine Canyon, so named for the plethora of travertine deposits exposed in the lower part of that tributary).  The travertine here formed by mineral rich waters that migrated up to the surface along the fault your gully occupies, where they evaporated in the arid desert air, and left primarily calcium carbonate behind as a cementing agent that welded rock fragments carried in the wash together into the breccia you are standing on.  Continue your descent, at about 6.95 miles the trail passes out of the gully to the right and back onto the colluvial slope below the Redwall Limestone-Muav Limestone contact (Figure 1A.1.13).  This abrupt contact is a major disconformity in the Grand Canyon, an erosional hiatus separating Middle Cambrian and Middle Mississippian sedimentary rocks, a gap representing about 175 million years of missing record (although the gap is only about 130 million years in places where the Devonian age Temple Butte Formation is sandwiched between the Redwall and Muav).  From here, the trail makes a long descending traverse of first the Muav Limestone, and then the Bright Angel Shale slope, as the gully rapidly expands into a full blown canyon.  The views across Boucher and Topaz Canyons to Marsh Butte are gorgeous at sunrise should you choose to ascend this way (Figure 1A.1.14).  While you maintain your balance on the rubbly trail, you may note that Marsh Butte is separated from the ridge that it terminates by a major fracture, the fracture is a continuation of the Muav Fault.  The widening side canyon you are descending aligns with this fracture along a NW-SE trend.  Close examination of the fracture reveals a down-to-the-southwest motion on the fault, probably related to recent Basin and Range extension.

Figure 1A.1.13.  The disconformable contact between the overlying Redwall Limestone and underlying Muav Limestone representing an erosional gap of about 175 million years, the largest disconformity in the Paleozoic sedimentary rock sequence.

Figure 1A.1.14.  The ridge forming the western wall of Topaz and lower Boucher Canyons that hosts Marsh Butte is split by the NW-SE trending Muav Fault which displays down-to-the-southwest motion related to ongoing Basin and Range extension.

A left-hand switchback at 7.63 miles (Map 1A.1.1) ends the traverse and the trail now plunges to the Tonto Platform below.  Be sure to look to the gully bottom left of your position; a large mound of travertine deposits accumulated in the drainage, although the stream course, when active, has more recently cut a path around the sides of the blockage.  The Boucher Trail reaches its junction with the east-west Tonto Trail at 7.97 miles (Map 1A.1.1).  The Tonto Trail intersection is marked by a large cairn (but no sign).  Heading to the right (north and east) along the Tonto Platform will eventually take you to Hermit Creek, so the Tonto Trail could be used to complete a loop hike from Hermits Rest down the Boucher Trail and up the Hermit Trail (or vice-versa). It is about five waterless miles between Boucher and Hermit Creeks, but the trail is well-defined and luxuriously level compared to the Boucher. Great inner canyon views and spectacular close up inspection of travertine deposits near Travertine Canyon provide plenty of diversions on a comparatively easy route.

From the junction, it is a relatively short drop through the Tapeats Sandstone to the Boucher Creek campsites and permanent water at 8.29 miles (nearly ten from the South Rim if you’ve done it all in a day) (Map 1A.1.1).  Just past the junction, a beautiful outcrop of Tapeats Sandstone displays herringbone crossbedding, a sedimentary structure indicative of wave action associated with beach and nearshore coastal environments (Figure 1A.1.15).  As you make your final descent, you may note that beds of sandstone gradually thicken to become a pervasive unit comprised on sandstones at the expense of mudstone layers which thin to nonexistence.  This gradual replacement of one rock type for another is known as an intercalated contact and it indicates that the depositional environments of the Bright Angel Shale and Tapeats Sandstone were laterally adjacent, and that one gradually replaced the other, in this case due to a rise in sea level in the Middle Cambrian. When you reach the campsites, don’t expect any shade, but they are about as secluded as one can get in the Grand Canyon.  Once you’ve had a chance to splash in the creek and rest a bit, take a look around; you may locate evidence of Louis Boucher’s (a.k.a. “the Hermit”) camp in the form of stone work foundations.  All that remains of his cabin are four walls and a fireplace.  The Great Unconformity is well exposed at the base of the cliff just north of camp; check it out while you are here.  The Great Unconformity is the erosional contact between the Tapeats Sandstone and crystalline basement rock below, a nonconformity representing 1.2 billion years of missing rock record.  A walk up Boucher Canyon offers ample opportunity to examine outcrops of the Tapeats Sandstone.  The sandstone was primary derived from local sources (erosion of the crystalline basement) and is generally coarse grained, with abundant feldspar, forming a relative immature sedimentary rock.  A look back up the canyon down which you descended offers a good view of the travertine mound filling the lower end of the drainage just above camp.  These deposits probably formed fairly recently in the Grand Canyon’s history, given their location within a pre-existing drainage; perhaps they formed during periods of relatively moist climate associated with past Quaternary glaciations when there would have been greater volumes of groundwater flow.  In this case, their proximity to a fault-controlled drainage suggests a ready source of water flowing from springs.

Figure 1A.1.15.  Herringbone crossbedding in the Tapeats Sandstone is indicative of oscillatory currents and wave action typical of a beach or nearshore coastal setting.

If time allows (you should have plenty if hiking in from Yuma Point or Hermit Creek camp), it is an easy walk down the gravelly bed of Boucher Creek to the Colorado River; bring lunch, find some shade at the river, and return in the late afternoon when it has cooled off in the canyon.  Alternatively, you might enjoy the solitude of the relatively shadeless campsites that can be found just downsteam of the Boucher Creek confluence with the Colorado.  Each tributary canyon to the Colorado offers something geologically unique, and Boucher Canyon is no exception.  The lower canyon faces the Tower of Ra on the skyline as it weaves through dark, foliated Vishnu basement (Figure 1A.1.16).  One of this drainage’s more interesting features is exposures of Late Proterozoic metasedimentary rock equivalent in age to the Vishnu Schist (this is the same rock, just not as highly metamorphosed).  These rocks preserve primary bedding features (Figure 1A.1.17a) and inclusions of unusually large volcanic clasts (Figure 1A.1.17b) that suggest their origin as sediment stripped from a rising volcanic island arc (and rapidly buried in an adjacent oceanic trench during the Mesoproterozoic).  The Vishnu basement here is relatively undisturbed by Zoroaster intrusives, containing only a few metamorphosed quartz pegmatite dikes (Figure 1A.1.18a) and quartz pegmatite fracture fillings (Figure 1A.1.18b), their presence here suggesting that the Vishnu basement in this area was some distance from a plutonic source.  When you reach the canyon mouth, head left down river for the best shade against the cliff that backs up the sandy beach below Boucher Rapids.  As with nearly all of the rapids in the Grand Canyon, these have formed where periodic debris flows pouring down the tributary drainage have dumped a huge quantity of bouldery debris into the river, forming a temporary blockage and steepening of gradient.  Note the calm pool of water above the rapids, and the frothy standing waves forming over the rapidly plunging river as it passes through the obstruction (Figure 1A.1.19).  Many of the boulders here are uniquely sculpted and polished by former, silt and fine sand laden, and higher flows of the Colorado River (Figure 1A.1.20).  Be sure to look for evidence of the debris flows which created Boucher Rapids as you hike back up the tributary to Boucher Creek camp, the bouldery stream terraces found at intervals along the stream course attest to the coarse nature of these flows and the power necessary to carry their contents all the way to the river (Figure 1A.1.21).

Figure 1A.1.16.  The hike down Boucher Creek from the campsite passes through a twisting corridor of dark, foliated Vishnu basement rocks; on the skyline, the terminus of the knife-edged ridge extending south from the Tower of Ra dominates.

Figure 1A.1.17.  The Vishnu Schist found in lower Boucher Creek is dominated by metasedimentary rock; low grade metamorphic rock comprised of sediments stripped from a rising volcanic island arc that often preserves primary bedding (A) and large volcanic clasts (B).

Figure 1A.1.18.  Zoroaster intrusives are rarely found in the Vishnu basement of lower Boucher Creek and generally consist of thin metamorphosed quartz pegmatite dikes (A) and fracture fillings (B).

Figure 1A.1.19.  Boucher Rapids has formed where bouldery debris deposited at the mouth of Boucher Creek has partially blocked the Colorado River; (A) a quiescent pool forms above the blockage, and (B) standing waves often form in the rapids where the rapid change in gradient causes swiftly flowing water.

Figure 1A.1.20. High flows of the Colorado River carry silt and fine sand that can sculpt and polish boulders such as this one comprised of Vishnu Schist left on the delta at the mouth of Boucher Creek.

Figure 1A.1.21.  Bouldery stream terraces found along lower Boucher Creek were likely deposited by periodic debris flows; flushed onward to the Colorado, these same materials partially block the river’s flow creating rapids.

Once you have completed your tour of Boucher Creek, you can return the same way you came in, or make this trek a loop hike by returning via the Tonto and Hermit Trails (see the descriptions of these trails under Tr1.5a and Tr1.3 respectively).  If you are planning to continue on the Tonto Trail downriver, head about three-tenths of a mile down Boucher Creek to its confluence with neighboring Topaz Canyon; the cairned trail junction can be found there.

Hiking Trail Maps

Map 1A.1.1.  Shaded-relief map of the northwest quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

Bright Angel, River, and Plateau Point Trails (Tr1A.2)

The Bright Angel Trail is certainly Grand Canyon National Park’s most popular, with its steady stream of day-hikers and backpackers alike, and it is considered by many to be the park’s premier hiking trail.  Its relative popularity is probably inherited from its ease of access, with its trailhead located in the heart of the Grand Canyon Village historic district.  As one of only a few rim-to-river trails, the Bright Angel offers ready access to the Inner Gorge and Colorado River; and it’s the best connected of any trail in the park, affording access to several other trails, including the east-west Tonto Trail, the short spur trail to Plateau Point, the River Trail which connects to the lower end of the South Kaibab Trail, as well as to the inner canyon end of the North Kaibab Trail at Bright Angel Campground/Phantom Ranch.  The Bright Angel is one of the aforementioned “Corridor” trails designated by the park service.  With regular drinking water stations, covered rest-houses along the way, and even ranger stations located at the trail’s halfway point (Indian Garden) and at trail’s end in the bottom of the canyon (at Bright Angel Campground), the Bright Angel is undoubtedly the safest trail in Grand Canyon National Park.  The Bright Angel’s corridor status and relative safety also mean that it is ideally suited for a beginning backpacking experience in the Grand Canyon, but don’t worry, even if you are a hiking and backcountry guru, the trail is plenty rigorous, and it never fails to provide an abundance of scenery and unique geological features too, enough to satisfy even the most seasoned veteran of the Grand Canyon’s earthly marvels.

The modern Bright Angel Trail follows the approximate route used for millennia by the many Native American groups that lived in and near to the Grand Canyon.  Early pioneers of European descent first built a trail in 1891 along the original Native American route in order to reach mining claims established below the rim at Indian Garden.  Quickly realizing that the trail’s true worth would be determined by tourist visitation, these pioneers immediately registered their trail as a toll road and extended the trail to the river; but the trail was eventually turned over to the National Park Service in 1928.  21st-century visitors hiking on the Bright Angel Trail can get a feel for its wealth of human history from ancient pictograph panels and historic structures, and it never hurts to earn the good vibrations of the canyon spirits by marveling at the trail’s construction over some of North America’s roughest terrain.

The park service warns that “at-large camping is not permitted on Corridor Trails; visitors must camp in designated campgrounds”; however, the Bright Angel Trail does offer some of the finest (and shadiest) camping areas below the rim, located at Indian Garden and Bright Angel Campground.  One additional convenience of the trail is that potable drinking water is seasonally available at several trailside locations (early-May through mid-October only), including Mile-and-a-Half Resthouse, Three-Mile Resthouse, Indian Garden Campground (4.8 miles), and Bright Angel Campground (9.5 miles).  Most Bright Angel Trail day-hikers attempt the out and back trip to Indian Garden Campground.  A longer day-hiking option is to include the round-trip spur trail to Plateau Point from Indian Garden, but you should start quite early if you plan to include this extended excursion.  Rim-to-river day-hikes should not be attempted, especially in the heat of summer.  However, should you desire such an undertaking, one likely scenario is a sunrise hike descending the South Kaibab Trail and then along the River Trail to the silver bridge where you can connect with the Bright Angel  Trail and ascend back to the rim.  A well-timed trip will bring you to Indian Garden by late morning, where you can rest in the shade, continue your ascent in the relative coolness of the late afternoon, and take advantage of water stations higher on the trail.

If you actually want to see and enjoy the canyon’s scenery and geological wonders, I would recommend a three-day outing that includes both the Bright Angel and South Kaibab Trails, with overnight stays at Indian Garden Campground and Bright Angel Campground, and which can be hiked in either direction (although more shade and a gentler gradient merit hiking out on the Bright Angel).  A stay at Indian Garden Campground should include the side-trip to Plateau Point, and for the ambitious hiker, a stay at Bright Angel Campground should include an excursion to the overlook on the Clear Creek Trail above the mouth of Bright Angel Canyon.  Hiking the Bright Angel could be combined with the North Kaibab Trail to make an unforgettable South Rim-to-North Rim trek of three days as well (staying overnight at Bright Angel and Cottonwood Campgrounds instead); or for the more adventurous (and experienced) hiker, your rim-to-river trek on the Bright Angel and South Kaibab Trails could be combined with an in-and-out trip on the Clear Creek Trail (only accessed from a trailhead just up Bright Angel canyon from Phantom Ranch).

The Bright Angel Trail descends along the head of Garden Canyon, where a natural break in the South Rim’s normally impenetrable cliffs has formed in rocks weakened by movement on the massive Bright Angel Fault. Views from the upper Bright Angel Trail are framed by imposing varicolored cliffs comprised of horizontal sedimentary rock layers deposited between 545 and 245 million years ago, during a period of earth’s history known as the Paleozoic Era (Figure 1.4).  Paleozoic means “ancient life”, and as you hike the trail, be sure to look for its evidence in the form of fossilized marine invertebrate fauna preserved in the rocks.  A hike on the Bright Angel Trail is a hike backwards through time.  Each sedimentary rock unit (called a formation) that you cross exhibits unique characteristics that enable easy identification, traits that when combined reveal its sedimentary facies and allow geologists to decipher its depositional setting.  The majority of this trail’s elevation change takes place in the upper four miles of trail via a series of switchbacks that can seem endless, although this section of the trail is fairly shady and with several natural water sources, there is more abundant plant and animal life which can make for interesting distractions.  As you approaching Indian Garden, the trail flattens out considerably as it traverses the desolate Tonto Platform, its gentle slopes brought on by rapid weathering of the Bright Angel Shale and its lack of abundant vegetation a result of soils developed on nutrient poor mudrocks.

Indian Garden forms an oasis in Garden Canyon long used by Native Americans.  Ralph Cameron, an early pioneer and one of the settlers who built the Bright Angel Trail, was able to secure an agreement with the resident Havasupai which allowed him to build a campground of sorts for early Grand Canyon tourists.  The enormous cottonwood trees still present at the site today which can be viewed from the rim are a testament to his entrepreneurship.  Potable water and state-of-the-art composting toilets add to the shady luxury of this designated campground.  If you are planning a multiday backpacking trip, camping at Indian Garden offers the bonus of a short three-mile round-trip hike to Plateau Point and its spectacular views of Granite Gorge.

Below Indian Garden, the Bright Angel Trail initially saunters along the right bank of perennial Garden Creek, but steepens considerably where the stream pours into the broad bowl of the lower Pipe Creek drainage, a section of trail affectionately known as the Devil’s Corkscrew.  Here, the trail can be unbearably hot during the summer months and the park service recommends that it “should only be attempted during the early morning or late evening hours”, so plan accordingly.  Beyond the Corkscrew, it becomes obvious that the Bright Angel Trail has dropped below the Tapeats Sandstone, lowermost of the Paleozoic sedimentary rock sequence, and into crystalline basement rocks, approximately 1.7 billion years old (Figure 1.4).  Pipe Creek has cut a narrow path through dark, vertically foliated Vishnu Schist, here and there injected by ribbons of pink Zoroaster Granite, the depths of the tributary canyon grading to the Colorado River, confined by the dark-walled Inner Gorge.   There are no potable water sources between Indian Garden and Bright Angel Campground, although filterable water can be found at the lower end of Pipe Creek and at its mouth where it empties into the Colorado River just below the River Resthouse.  The park service warns that from the Pipe Creek/River Resthouse area to Bright Angel Campground, “the trail traverses exposed sand dunes for over a mile until reaching the silver bridge across the Colorado River. Again, during hot weather, these sand dunes become a dangerous slog.” Fortunately, from the silver bridge, it is a short jaunt to Bright Angel Campground.

The Bright Angel trailhead is located on the Rim Trail (Map 1A.2.1), just west of Kolb Studio in Grand Canyon Village, within easy walking distance of the Hermits Rest Route Transfer (Stop #6 on Map 1A.2 and Map 1A.2.1).  It is also only a short stroll from Maswik Lodge, Bright Angel Lodge, and several South Rim parking areas. The park service suggests that “out of consideration for daytime park visitors, it is recommended that overnight hikers park at Parking Lot D (the Backcountry Information Center parking lot).  Though this is not the closest parking area, it is the most secure and is also where the largest number of parking spaces are located.”  Your descent on the Bright Angel Trail initially feels a bit like a stroll on Park Avenue (the wide, gentle gradient of the well-groomed trail goes easy on your knees, but the crowds of tourists with limited knowledge of trail etiquette can be aggravating).  You encounter the first of many switchbacks, a left-handed one here, about 400 feet into your long descent, an unremarkable location other than it begins a lengthy straightaway bounded on the inside by outcrops of Kaibab Limestone, your first Paleozoic rock unit (in descending order) (Figure 1.4).  The limestone is distinctly mottled, containing many protruding nodules of darker gray chert; the nodular chert contains the siliceous remains of sponge spicules (the only hard parts of sponges), their presence providing natural resistance to weathering (Figure 1A.2.1).  The widespread abundance of chert within the Kaibab stiffens the unit against weathering and erosion, and is a significant factor contributing to its cliff-forming, rimrock status (as well as its relative resistance throughout the Grand Canyon region).  The limestone is principally composed of calcium carbonate mud, the remains of tiny planktonic marine organisms, but look carefully for fossilized brachiopods, bryozoans, crinoids, and horn corals, the latter creatures being benthonic, or bottom-dwelling organisms.  The outcrops provide evidence of the Kaibab Limestone’s origins, the Grand Canyon area occupying a marine shelf covered by shallow, tropical seas about 260 million years ago during this formation’s deposition.

Figure 1A.2.1 Chert nodule in Kaibab Limestone displaying sponge spicules copyrighted

Figure 1A.2.1.  Chert nodules in the Kaibab Limestone often contain fossilized sponges (note the light-colored chicken-wire pattern within the darker rounded blob of chert).

The trail passes through a tunnel bored through the limestone at 0.15 miles (Map 1A.2.1); be sure to look up and to the left about 30 feet on the down-side of the tunnel exit for pictographs painted with red mud, an indication of this trail’s long use.  The images where probably made by the Ancestral Puebloan people who inhabited the area between 1250 and 850 years ago.  Continue on the straightaway, ahead of you lies the western headwall of Garden Canyon and the gradually descending trail (Figure 1A.2.2).  Looking ahead, carefully observe the trail and locate the right-hand switchback, then backtrack up the trail a short distance; you should be able to discern a change from buff-colored ledgy limestone above to a reddish slope-forming layer below, this is the contact between the Kaibab Limestone and Toroweap Formation which you will soon cross.  Tracing the whitish, basal portion of the Kaibab Limestone to the left of the switchback, you may notice a slight offset about half way between the switchback and the point where the trail crosses the contact, this minor down-to-the-right offset is a small subsidiary fault to the main Bright Angel Fault that passes up through the head of the canyon just ahead.  At about 0.36 miles (Map 1A.2.1), your tread passes the actual contact between units, and in about 100 yards you reach the right-hand switchback you observed earlier.  Take a brief rest just ahead of the switchback; now that you have crossed to the western headwall, this is a great position from which to consider evidence of the Bright Angel Fault.  Recall that you are standing on mudrocks of the Toroweap Formation.  Facing west, first look upslope to your left where you can see the lowest cliff-steps of the Kaibab Limestone; then rotate until you are facing downslope and to the right.  You should be able to make out more limestone cliff bands of the Kaibab extending some 200 feet below your current position, indicating down-to-the-southeast displacement on the Bright Angel Fault.  From the switchback, now look to the northeast down the axis of Garden Canyon, and incidentally, right up Bright Angel Canyon across the Colorado River (Figure 1A.2.3); note the unusual linearity of these two canyons, a result of stream erosion of rocks weakened by fracturing along the trace of the Bright Angel Fault.

Figure 1A.2.2 Faulted contact between Kaibab Lm and Toroweap Fm, Bright Angel Trail copyrighted

Figure 1A.2.2.  The western headwall of Garden Canyon; careful observation reveals the faulted contact between the Kaibab Limestone and underlying Toroweap Formation.

Figure 1A.2.3 Fault-aligned Garden and Bright Angel Canyons copyrighted

Figure 1A.2.3.  The valley of Garden Creek (near view) and Bright Angel Creek (more distant); together, they form a linear set of canyons dissected along the zone of weakness created by repeated movements on the Bright Angel Fault.

A lengthy straightaway extends for about three-tenths of a mile below this second switchback.  In roughly 600 feet, the trail crosses the ravine forming the upper end of Garden Creek.  Good exposures of Kaibab Limestone cliff bands are an indication you are back on the downdropped side of the Bright Angel Fault.  Shortly, your traverse crosses into outcrops of the Toroweap Formation.  At 0.70 miles  (Map 1A.2.1) from the trailhead, you navigate two switchbacks in rapid succession, first a left turn, then a right; excellent exposures of alternating layers of limestone, shale, and evaporites comprising the Toroweap Formation occur at the first one (Figure 1A.2.4).  This unique interlayering of sediments suggests that about 265 million years ago, when the Toroweap Formation was accumulating, the Grand Canyon area occupied an arid, fluctuating shoreline position on a shallow marine shelf.  After the fourth switchback, your traverse resumes a gentle descent and at 0.92 miles (Map 1A.2.1), you pass through a second tunnel.  Conveniently, this tunnel marks a geologically significant location where you recross the trace of the Bright Angel Fault.  As you enter the tunnel, the rocks are comprised of Toroweap Formation on the downthrown side of the fault, but within the tunnel, and beyond, the rock is fine-grained, quartz sandstone of the Coconino Sandstone.  Upon entering the tunnel, a cliff of Coconino Sandstone rises well above you on the left, but that same cliff lies below the level of the trail on the right.  As you walk through the tunnel, note the evidence of faulting indicated by sheared rock, chemically altered to a greenish color, as well as by a network of calcite-filling fractures; these features are the result of groundwater solutions moving along the fault and the precipitation of void-filling minerals.  Beyond the tunnel, you are met by a wall of 270-million-year old Coconino Sandstone, exhibiting its unique mega-scale crossbedding (Figure 1A.2.5).  The tilted crossbedding is separated into distinctive, subhorizontal layers by bounding surfaces, features that indicate wind deflation of the previously deposited sand layer below, prior to migration of another set of sand dunes above.  The steeply dipping crossbeds form on the lee, or downwind side of the migrating dune and so can be used to infer the prevailing southeasterly direction of wind transport within the desert erg that formed this deposit.

Figure 1A.2.4 Toroweap Formation, comprised of interbedded shale and gypsic evaporites sandwiched between Lm layers copyrighted

Figure 1A.2.4.  Alternating layers of limestone and interbedded shales and evaporite deposits in the Toroweap Formation; bedding features used by geologists to infer a depositional environment associated with an arid coastal setting undergoing minor sea level fluctuations.

Figure 1A.2.5 Megacrossbedding produced by sanddune migration in the Coconino Sandstone copyrighted

Figure 1A.2.5.  Mega-scale crossbedding in the Coconino Sandstone; here, the steeply dipping crossbeds indicate a southward-directed prevailing wind within the desert erg system that formed them.

Once past the tunnel, the Bright Angel Trail plunges rapidly through multiple switchbacks on a widening cone of talus, mass wasting debris mainly composed of weathered chunks of Kaibab Limestone and Toroweap Formation avalanching downward along the trace of the Bright Angel Fault.  As you descend, note the approach of a very distinct, nearly horizontal surface in the cliff face to the west side of the talus cone; which you meet at about 1.34 miles (Map 1A.2.1) into your trek, near the seventh switchback (a right-handed one) below the previously mentioned tunnel. This feature marks the abrupt contact between the buff-colored Coconino Sandstone, and the brick-red Hermit Formation (Figure 1A.2.6a).  Normally a slope-former covered in soil and rocky debris, the Hermit is well exposed here and worth your full attention.  Close examination of this contact line impresses upon the observer just how rapidly depositional environments can change from the accumulation of one unit to another.  The brick-red Hermit is composed of mudrocks and minor sandstones, thought to have been deposited by low-energy riverine and deltaic systems on a low-gradient, floodplain-dominated, tropical coastline around 275 million years ago.  The sharp break to desert-deposited sands of the Coconino is quite distinct, but the contact also preserves elongate, sand-filled desiccation fractures (the cross-sectional view of large-scale mudcracks) at the top of the Hermit (Figure 1A.2.6b), strengthening the argument that extreme aridity abruptly overwhelmed the region just prior to the arrival of migrating Coconino sands.  The abrupt contact between formations that is exhibited here is an excellent example of what geologists call a disconformity, a surface formed during a period of subaerial exposure and nondeposition or during minor erosion.

Figure 1A.2.6 The Coconino Sandstone - Hermit Formation Contact copyrighted

Figure 1A.2.6.  The abrupt, disconformable contact between the Coconino Sandstone and Hermit Formation (A); marked by large, elongate, sand-filled fractures in the top of the Hermit (B) that indicate a rapid change to extremely arid conditions roughly 270 million years ago.

After leaving this marvelously expressive contact, the trail quickly completes its current series of swithbacks and begins to descend more gradually eastward, back across the valley head on a short straightaway.  At about 1.62 miles (Map 1A.2.1), you reach the aptly-named Mile-and-a-Half Resthouse, consisting of an emergency phone, water spigot, two shade-covered rock pavilions, and toilets (located 100 yards away).  Interestingly enough, the toilets lie near the contact between the Hermit Formation and the Supai Group; the Supai actually consists of four formations making up nearly 1000 vertical feet of the Grand Canyon’s Paleozoic sequence (Figure 1.4).  The Supai Group formed between 310 and 285 million years ago on an arid, low-gradient coastline alternately covered by tidal mudflats related to temporary sea-level rise, and dune fields associated with minor sea-level retreat and subaerial exposure.  Oddly enough, these sea level fluctuations were triggered by events taking place half a world away during the Permian, caused by growth and decay of ice sheets over Gondwana, a large continental mass centered over the South Pole.  As the continental ice sheet grew, water in the world ocean was locked up on land, sea level fell, and the coastal deserts of the proto-North American southwest to expanded.  Waning of the ice sheet dumped water back into the world ocean, sea level rose, and shallow seas inundated the Grand Canyon region with extensive mudflats.

Just below the toilets, a prominent crossbedded, red sandstone cliff marks the position of the Esplanade Sandstone, uppermost unit of the Supai Group, accumulated during an extended period of marine retreat and sand dune migration over a large coastal desert erg.  After passing rapidly down  through the Esplanade, the trail switchbacks to the left and begins another gentle traverse of the underlying slope-forming mudrocks of the Wescogame Formation.  Examine the western slope above you on this gradual descent, the overlying cliff band of the Esplanade is easily distinguished, and above that, the stair-stepped layers of the Hermit, Coconino, Toroweap, and Kaibab are all on display (Figure 1A.2.7).  The Bright Angel Trail snakes slowly down through multiple switchbacks within the Supai units on its way to the Three-Mile Resthouse, crossing Garden Creek wash and the Bright Angel Fault twice in the near distance, but then sticking to the slopes just to the right of the fault trace clear to the resthouse.  Although the Supai traverse seems endless, but on the Bright Angel Trail, descending through this section of strata is actually quit short, a feature not shared by most rim-to-river trails.  (Experienced rim-to-river hikers dread the “Supai Traverse” on most of these trails; it has a reputation for long, undulating, and sunny exposures that have you day-dreaming of the Redwall contact somewhere ahead).

Figure 1A.2.7 The Esplanade Sandstone and upper Paleozoic units copyrighted

Figure 1A.2.7.  As viewed from the Bright Angel Trail’s traverse of the Wescogame Formation; the western wall of Garden Canyon prominently displays the Esplanade Sandstone (lowermost cliff band) and stair-stepped sedimentary rock formations higher in the Paleozoic section.

As you approach the Three-Mile Resthouse, the trail briefly steps into the bed of Garden Creek wash at 3.04 miles (Map 1A.2.1), where you can see polished gray limestone belonging to the Redwall Limestone.  Shortly beyond the wash, views to your left reveal the western slopes of Garden Canyon which nicely display all four units of the Supai Group overlying the Redwall (Figure 1A.2.8), each unit easily distinguished by the cliff-slope-cliff-slope pattern caused by differential erosion.  Offset on the Bright Angel Fault can be easily observed.  Across the wash to the west lies the upthrown (northwest) side of the fault, but over 100 feet below, and to the right of your position, the Three-Mile Resthouse can be observed to sit on the downthrown (southeast) side of the fault.  It rests on red mudstones of the Watahomigi Formation, lowermost of the Supai Group, near its contact with the Redwall Limestone.

Figure 1A.2.8 The Supai Group and Supai - Redwall Contact copyrighted

Figure 1A.2.8.  Garden Creek wash exposes the top of the Redwall Limestone on the upthrown side of the Bright Angel Fault; in the background, the western side of Garden Canyon nicely displays all four stair-stepped units of the Supai Group.

Three-Mile Resthouse lies just off the main trail near a Redwall promontory overlooking Garden Canyon at about 3.21 miles (Map 1A.2.1), offering an emergency phone, water spigot, a shade-covered rock pavilion, and toilets.  If you are out for a day-hike, this is also a good location to turn around.  A brief walk up the spur trail to the pavilion and water spigot affords an excellent view upcanyon along your route of descent.  No clearer view of the down-to-the-east (left as you look upvalley) offset on the Bright Angel Fault can be found on this trek (Figure 1A.2.9).  Cliffs formed by the Coconino Sandstone and sandstones within the Supai Group are visibly higher to the right (west) of the fault, then to the left (east); but most noticeable is the offset between the Redwall Limestone and rocks of the Supai Group just in front of you.  You may also notice the prominent “fin” of rock jutting toward you (just right of the zig-zagging trail); this forms the plane of the fault within the Redwall, where precipitation of minerals from groundwater solutions cruising along the fault has made the rock more resistant than the original limestone.  Once you return to the main trail, a series of switchbacks known as Jacob’s Ladder takes you down through the only gap in Redwall Limestone, the breakdown slope produced by weathering and erosion along the Bright Angel Fault; you may notice that outcrops of the limestone are highly fractured (although recemented), a result of repeated fault movements.  Veterans of rim-to-river trails will recognize that passages through the Redwall such as this one are usually associated with zones of weakness in the rock created by faults oriented more or less perpendicular to the canyon’s rims.

Figure 1A.2.9 The Bright Angel Fault from 3-mile Resthouse copyrighted

Figure 1A.2.9. The Bright Angel Fault from Three-Mile Resthouse; probably the best location along the trail to observe the down-to-the-east offset of rock units related to the Bright Angel Fault.

The Redwall Limestone was deposited on a warm, shallow, continental shelf between 350 and 320 million years ago as indicated by its composition, trillions of tiny fossil fragments of brachiopods, corals, bryozoans, crinoids, and sponges; if you are lucky, you may even find a piece large enough to allow identification of the organism (please leave it where you find it though).  As you descend, consider the countless numbers of marine organisms that make up the more 450-foot thick cliff you are passing through.  While fossil hunting, you will likely see that the Redwall Limestone is actually a dull gray color, its red is merely a coating of mud that it receives from weathering of the Hermit and Supai rocks above.  John Wesley Powell originally named this unit for the ubiquitous presence of its massive red-colored cliffs throughout the Grand Canyon; although he too recognized its rather boring appearance close up.  The Redwall cliffs are commonly pitted by caves, and Garden Canyon’s soaring cliffs are no exception; the caves having formed by groundwater dissolution, mainly along joints within the rock unit.  Many of the caves formed long ago when groundwater levels were higher (downcutting of the canyon has lowered the regional water table).  The top of the Redwall is also pock-marked with semicircular depressions representing ancient sinkholes, some may be related to the caves formed within the limestone unit.  The sinkholes developed during a period of subaerial exposure of the Redwall Limestone, when rapid weathering associated with a tropical setting generated topography known as karst.  Although these karst features are not found here in Garden Canyon, elsewhere in the Grand Canyon the sinkholes and caves are filled with 315-million-year-old conglomerates and mudstones of the Late Mississippian age Surprise Canyon Formation (Figure 1.4).

The base of the Redwall and a fine view of lower Garden Canyon (Figure 1A.2.10) are reached near 3.66 miles (Map 1A.2.); the Redwall-Muav Limestone contact is obscured by mass wasting debris near the trail, but a deep grotto formed by a minor tributary of Garden Creek across the valley on the left reveals its approximate location.  Just ahead, the trail rounds a bend to the right and crosses an eastern tributary of Garden Creek over the Trans-canyon pipeline bringing water to the South Rim; the Redwall-Muav contact lies at the bottom of the wash.  After exiting the tributary, Bright Angel Trail begins a long, gradual descent toward Indian Garden Campground, mainly on stream terrace deposits of Garden Creek.  Although not obvious in the nearby canyon walls, a gap of some 130 million years separates formation of the Muav Limestone from the Redwall.  Missing completely are sedimentary rocks representing the 505 to 408 million years of the Ordovician and Silurian Periods, although a small portion of the Devonian is present in the form of the roughly 362-million-year-old Temple Butte Formation (Figure 1.4).  The Temple Butte was deposited in coastal estuaries and tidal flats occupying former river valleys that had been cut into the top of the Muav Limestone.  Subaerial exposure and ensuing erosion removed much of the unit.  This formation, much like the Surprise Canyon, occurs discontinuously over the region, and its isolated patches make it an elusive unit to find.  In Garden Canyon, a discerning eye may be able to pick out a purplish-colored, lens-shaped outcrop about 35-feet thick roughly 200 feet up the right-hand (eastern) wall; here it lies sandwiched between the massive buttress of the Redwall Limestone above, and the ledgy olive-drab layers of the Muav Limestone below.

Figure 1A.2.10 Lower Garden Creek Canyon copyrighted

Figure 1A.2.10.  Lower Garden Canyon; here the shear walls of the Redwall Limestone overlie ledgy slopes of Muav Limestone, often covered in mass wasting debris consisting of talus cones and slope colluvium.

At 4.08 miles (Map 1A.2.1), the Bright Angel Trail bends right into a small tributary wash of Garden Creek; just to the left in the wash, lies the Trans-canyon pipeline.  The banks of the wash reveal thin beds of the olive-gray Muav Limestone.  Beyond this tributary, Garden Creek occasionally cuts into the toe of the western slope deeply enough to expose outcrops of the Muav (Figure 1A.2.11).  The 525-million-year-old Muav Limestone forms the uppermost layer of the Middle Cambrian Tonto Group, a three-unit package of sedimentary rocks accumulated during a major marine transgression onto the western margin of the proto-North American continent.  The threesome of sedimentary rock layers includes the Bright Angel Shale and Tapeats Sandstone below the Muav, and the entire package rests on the peneplained surface eroded into Proterozoic crystalline basement and Supergroup rocks alike.  As the Cambrian seas gradually inundated the continental margin, the high-energy sandy shoreline deposits of the Tapeats were buried by slack-water, muddy sediments of the Bright Angel, which in turn was blanketed by deeper water limestones of the Muav; a distinctive pairing of rock formations referred to by geologists as a transgressive sequence.

Figure 1A.2.11 The Bright Angel Shale copyrighted

Figure 1A.2.11.  Exposures of the Muav Limestone’s olive-gray muddy limestones along Garden Creek.

Once past the Trans-canyon pipeline, the valley floor of Garden Creek begins to widen and stream terrace deposits are preserved along the lower slopes.  The trail itself sticks closely to the stream channel, confined between the terraces.  In the past, the Havasupai Indians farmed the fertile soils on these terraces, and they may have served such a purpose for more ancient peoples as well.  Widening of the valley is in response to the transition from Muav Limestone into the less resistant Bright Angel Shale; this part of the valley merges with the broad, gently undulating surface of the Tonto Platform, a distinctive topographic bench formed in this part of the Grand Canyon where rapid weathering and erosion of the Bright Angel has cause collapse and backwasting of overlying more resistant layers.  The Muav-Bright Angel contact is not evident because of burial under a thick accumulation of recent mass wasting and stream deposits.

The Bright Angel Trail becomes quite gentle (for the Grand Canyon), and even floored by sand in places.  At 4.56 miles (Map 1A.2.1), a sign indicates that Indian Garden Campground lies just ahead; and on your left, a spur trail takes you to the Ranger Station.  Continue on the main trail, and in about one tenth of a mile, another spur trail on your left takes you to the upper end of the campground.  If your goal is overnight camping, turn in here and pick an empty site, they are first-come, first-served, but by permit only.  A short distance ahead on the main trail at 4.84 miles (Map 1A.2.1), you reach a staging area with toilets, a water spigot, and benches for the weary; take a load off and rest awhile.  If you listen carefully (difficult with all the congestion), you may hear the gurgling waters of Garden Creek, feed by a spring just above the staging area near the campground.  The lush riparian vegetation surrounding you, including the massive cottonwoods that offer you a shady campsite or bench rest, owe their existence to this spring and stream (Figure 1A.2.12).

Figure 1A.2.12 Shade Trees at Indian Garden Campground copyrighted

Figure 1A.2.12.  One of the many gorgeous riparian trees offering shade for the weary backpacker in Indian Garden Campground.

The staging area also serves as the juncture for several hiking trails.  Just to the left, the trail junction for the Plateau Point Trail and Tonto Trail West; however, continuing to the far right, the main trail heads down the eastern side of Garden Creek on its way to the Silver Bridge and beyond.  My working assumption is that you have come to see Plateau Point first.  As I suggested, this trip should involve an overnight stay at Indian Garden Campground (if for no other reason, but that you’ll want to hit the promontory close to sunrise and/or sunset).  But if you got an early start on the Bright Angel Trail, the extra three miles you will be adding by tackling this short trail is not without its rewards (keep in mind this makes for a total trek of over twelve and a half miles out and back, not to mention the elevation changes, desert heat, and exposure – you were warned).  Head left off the main trail just after the Indian Garden staging area and quickly cross Garden Creek; depending on your hiking pace, try to start at least an hour before sunrise or sunset.  The Plateau Point Trail is wide, well maintained, and heavily traveled.  Initially, it climbs slowly as it contours in and out of several large gullies draining into Garden Creek; but eventually the trail ascends from Garden Creek’s western embankment and begins to gently undulate over the Tonto Platform.  The much less traveled, narrow path of the Tonto Trail veers off to the west (left) at 0.73 miles (Map 1A.2.2), a wonderful trail in itself, best saved for another day.  You really can’t miss the route to Plateau Point, and in about 1.44 miles, you reach your destination; here is where the fun begins.

If a Grand Canyon sunrise or sunset is what you seek, Plateau Point is one promontory you don’t want to pass up (Figure 1A.2.13 and 1A.2.14).  The relative solitude, the gentle breezes, the feel of a waxing or waning sun on your face, the ever changing pastels of the surrounding canyon walls marching away to ever greater height and distance, and the contrasting proximity of the black depths of the inner gorge; all combine to provide a sense of place, and a sense of your relative insignificance among the grandeur of the world.  What more could you ask for?  Well, the geology is pretty amazing too!

Figure 1A.2.13 Sunset over the Inner Gorge from Plateau Point copyrighted

Figure 1A.2.13.  A view down the inner gorge of the Colorado River from Plateau Point; sunlight plays over bedding in the Tapeats Sandstone as an early May the sun sets between rocky battlements.

Figure 1A.2.14 Inner Gorge Sunset from Plateau Point, looking upcanyon toward the mouth of Bright Angel Creek copyrighted

Figure 1A.2.14.  A contrasting view up the inner gorge of the Colorado River from Plateau Point; Granite Gorge lies in shadow, but Brahma and Zoroaster Temples, capped by the Coconino Sandstone, lie bathed in the fading sunlight of a setting May sun.

Plateau Point is formed of the resistant Tapeats Sandstone, lowermost unit of the Middle Cambrian Tonto Group, and the first of three sedimentary rock units recording a major marine transgression onto the western margin of proto-North America.  As previously describe, the sands comprising this formation were deposited as beach and nearshore sediments under the relatively high-energy conditions associated with wave action and long shore drift.  At Plateau Point, crossbedding produced by these currents is readily observed; although the most interesting features preserved in the sandstone are the trace fossils of trilobites and marine worms (Figure 1A.2.15).

Figure 1A.2.15 Trilobite resting burrow (A) and Worm burrow (B) Trace Fossils in the Tapeats Sandstone

Figure 1A.2.15.  Trilobite resting burrows (A) and marine worm tracks (B) in the Tapeats Sandstone are indicative of nearshore deposition in agitated waters.

Plateau Point projects over the inner gorge of the Colorado River above its confluence with Pipe Creek Canyon.  A view up canyon from Plateau Point, along Upper Granite Gorge, or up the canyon of Pipe Creek, takes in some of the most complex geology in all of the Grand Canyon.  First, take a close look at Pipe Creek Canyon (Figure 1A.2.16); the upper canyon, and its far eastern wall comprising Cedar Ridge (bathed in sunlight) in hosts the South Kaibab Trail (Tr.1A.4).  Follow the canyon wall downward, prominent cliff bands formed by the Kaibab Limestone, Coconino Sandstone, Esplanade Sandstone, Redwall Limestone, and Tapeats Sandstone should be easy to pick out, making it equally easy to establish the position of intervening slope forming rock units (Figure 1.4).  Locate the contact between the Tapeats Sandstone and the underlying crystalline basement; this nonconformity (an unconformable contact between sedimentary rock and crystalline igneous and/or metamorphic rock) was first recognized by John Wesley Powell and is known as the Great Unconformity, here representing more than 20 km of uplift and erosion, and 1.2 billion years of missing rocks.  The rough, dark rocks of the eastern and upper portions of the inner canyon of Pipe Creek are comprised of the 1.75-billion-year-old Brahma Schist of the Grand Canyon Metamorphic Suite (Figure 1.4), some of the oldest rocks in the Grand Canyon.  The Bright Angel Fault passes down the length of the lower inner canyon between the ridge and trail shown in the lower right corner of Figure 1A.2.16, separating the Brahma Schist from younger granites of the Pipe Creek Pluton, part of the roughly 1.70-billion-year-old Zoroaster Plutonic Complex (Figure 1.4) which form the near wall of the inner canyon.  The trail on the lower right is part of the Bright Angel Trail where it descends to the floor of Pipe Creek Canyon through Brahma Schist.

Figure 1A.2.16 Pipe Creek Canyon and Cedar Ridge from Plateau Point copyrighted

Figure 1A.2.16.  Pipe Creek Canyon; its far wall forms Cedar Ridge and displays the complete stratigraphy of the Grand Canyon; its inner canyon exposes the Great Unconformity and schists and intrusives representative of the Grand Canyon Metamorphic Suite and Zoroaster Plutonic Complex.

Now reorient your view up the inner gorge of the Colorado, using Brahma and Zoroaster Temples as a focal-point (Figure 1A.2.17).  In the distance, below Brahma Temple, the Upper Granite Gorge veers to the right, and the canyon of Bright Angel Creek veers to the left.  At the lip of the inner canyon formed by this confluence (looking not unlike the prow of an advancing ship), the Tapeats Sandstone forms a familiar cliff-band resting on the darker rocks of the crystalline basement, marking the Great Unconformity.  Above this cliff, the rest of the Paleozoic sequence rises skyward in an alternating series of recognizable slopes and cliffs.  But, what is so geologically amazing about this view is what lies in the foreground, stratigraphically below the Great Unconformity.  The geology is quite complex here, so please follow my led; the numbers on Figure 1A.2.17 correspond to the text described here.  (1) First look to your right; the Tapeats Sandstone and its blanket of Bright Angel Shale sail in from the far right, resting on crystalline basement as expected, but near the confluence of Pipe Creek Canyon with Upper Granite Gorge, a block of Tapeats (carrying a veneer of Bright Angel Shale) is offset by down-to-the-west movement on a splay of the Bright Angel Fault.  This movement is associated with ongoing Basin and Range extension beginning about 17 million years ago.  It gets more interesting.  (2) Let your eyes slip further down the eastern wall of Pipe Creek’s inner canyon; notice the oblong-shaped body of nearly black-looking rock.  Careful examination of this rock reveals that it is folded at nearly a right angle, up to the east.  This body of rock is part of the 1250-million-year-old Bass Formation, lowermost unit of the Grand Canyon Supergroup.  The remnant clinging here to the eastern wall of Pipe Creek Canyon was folded by an earlier phase of movement on the Bright Angel Fault, also produced by extension, but in this case caused by rifting of the supercontinent of Rodinia some 650 million years ago.

Figure 1A.2.17.  Upper Granite Gorge looking upriver from Plateau Point; the geology on display may be the most complex in all of the Grand Canyon.

Switch your attention across the river on the downcanyon side of Bright Angel Canyon.  Begin on the far left.  (3) You see thick, cliff-forming layers resting on the rough gray rocks of the crystalline basement as before, but these are Bass Formation, not Tapeats Sandstone.  Above the Bass is a distinctively brick-red slope-forming unit, this is the Hakatai Shale; and overlying this layer is another massive cliff-former, the Shinomo Sandstone, in places capped by a thin veneer of the Dox Formation.  These units form the lower Unkar Group, the basal portion of the Mesoproterozoic Grand Canyon Supergroup, and they are tilted to the northeast, a little difficult to observe in this view because the tilting is away from you and up Bright Angel Canyon to the northeast.  (4) Notice that the Supergroup rocks do not appear in the eastern wall of Bright Angel Canyon which has formed directly along the trace of the Bright Angel Fault.  Although eroded away, this fault once formed the back edge of a large slab of crust rotated down and to the west as a one-sided graben, now preserved as the northeast-tilted Supergroup rocks truncated against the fault plane.  (5) A splay of the Bright Angel Fault remains just downcanyon of the Bright Angel Canyon confluence where it offsets a wedge of Supergroup rocks down to the east, backwards into the main fault zone, forming a small, reverse-tilted graben within the larger one.  This deformation was produced by the same Neoproterozoic extensional motion on the Bright Angel Fault that produced the folding in the Bass Formation discussed earlier.  So where is the Tapeats?  Well, geologists believe that the tilted Shinomo Sandstone formed a resistant island in the rising waters associated with the Middle Cambrian marine transgression, and the Tapeats Sandstone was only deposited around its edges; it took the deeper water deposition of the Bright Angel Shale to bury the island.

Return to Indian Garden Campground at your leisure.  After a fine repast and a good night’s sleep, you’ll be fresh for your climb to the South Rim, or your continued descent to the Colorado River and points beyond.  If you are headed to the river, make your way to the Indian Garden staging area described earlier (Map 1A.2.1).  From there, take the main trail, staying to the right, and head down the east side of Garden Creek.  Initially, your continued hike is on soil and regolith weathered from the Bright Angel Shale, the sedimentary rock forming the surrounding slopes and capping the Tonto Platform.  In about three-tenths of a mile, 5.15 miles from the trailhead, you reach the Bright Angel Trail’s junction with the eastbound Tonto Trail (Map 1A.2.2).  Remain on the Bright Angel, shortly, it drops from the Bright Angel slope and passes the contact with the Tapeats Sandstone.  As you descend, the trail becomes increasingly confined by rising walls of Tapeats where Garden Creek has cut a narrow gorge.  The Tapeats cliffs have a rugged, striped, or ledgy appearance caused by differential erosion of alternating, weaker layers of thin mudstone interbedded with thicker, more resistant layers of sandstone.  The sandstone composition consists almost entirely of quartz sand and small pebbly lenses, indicative of wave action associated with a beach environment about 545 million years ago.

Near 5.66 miles (Map 1A.2.2), about four-tenths of a mile after entering the Tapeats gorge, the Great Unconformity becomes exposed beyond a pile of rockfall debris to the right of the trail.  Just prior to encountering this rockfall, a faint trail on the left crosses Garden Creek; the trail leads to several Ancesral Puebloan granaries tucked up under a slightly overhanging ledge of Tapeats Sandstone and to great exposures of the Great Unconformity.  It is worth dropping your backpack at the trailside and walking over to visit the granaries and the unconformity.  Figure 1A.2.18 shows two photographs of the granaries built by Native Americans roughly 900 years ago as they appeared in May, 2017.  Please respect these beauties and the ancients who constructed them; leave them as you find them!  Exposures of the Great Unconformity occur a few dozen yards further along the cliff face.  This nonconformable erosion surface separates the 1700 million-year-old crystalline basement from the overlying Tapeats Sandstone, and represents roughly 1.2 billion years of missing rock record.  The unconformity is easily distinguished here where the weathered gneissic rock of the Pipe Creek Pluton is overhung by more resistant quartz sandstone of the Tapeats (Figure 1A.2.19a).  Close examination of the contact shows angular rock fragments of the crystalline rock in a matrix of finer sand-sized grains (Figure 1A.2.19b).

Figure 1A.2.18.  Ancestral Puebloan granaries constructed roughy 900 years ago adorn a cliff-side overhang at the contact between resistant Tapeats Sandstone and the upper surface of well-weathered crystalline basement rocks in Garden Canyon.

Figure 1A.2.19.  Exposures of the Great Unconformity in Garden Canyon occur in the Tapeats narrows, about four-tenths of a mile below the junction of the Bright Angel Trail and Tonto Trail; the unconformity here is characterized by well-weathered crystalline basement overhung by more resistant Tapeats Sandstone (A), the contact itself exhibits broken up fragments of granitic rock in a matrix of coarse, quartz-rich sand (B).

Return to the Bright Angel Trail. In several hundred feet past the rockfall, expressive, pink pegmatite dikes cross-cut the older intrusives; and after about one-tenth of a mile, the crystalline rocks change to the darker gray, vertically foliated Vishnu Schist.  Vishnu metamorphic rocks originated as mud and volcanic ash deposited in an oceanic trench adjacent to the 1.75-billion-year-old Yavapai volcanic island arc; while the plutonic igneous rocks formed as magma generated in the arc’s subduction zone coalesced in large chambers beneath the growing island arc. Continue down the Tapeats gorge, the cliffs of sandstone and crystalline basement continue rising to the west (left), but on the right, a gradually narrowing ridge separating Garden Creek from Pipe Creek Canyon (which you can’t see) loses its Tapeats cap and the crystalline basement rocks become fully exposed.

At 6.10 miles (Map 1A.2.2), the trail bends to the right and reaches a low saddle in the now granitic ridge before plunging into Pipe Creek Canyon.  To your left, Garden Creek cuts a narrow swath through the fleshy-colored granite of the Pipe Creek Pluton which becomes well exposed here (Figure 1A.2.20).  Through the Garden Creek-carved notch, Upper Granite Canyon can be seen; Supergroup rocks including the Bass Formation, Hakatai Shale, and Shinomo Sandstone are exposed in the cliffs immediately above the crystalline basement, while Coconino-capped Budda Temple rises in the background.  Shortly, the Bright Angel Trail begins an abrupt descent to the floor of Pipe Creek along an energetic series of switchbacks known as the Devil’s Corkscrew; the route literally gouged from the dense crystalline basement, occasionally offering spectacular views of the South Rim’s Yavapai Point looming far above.  As the trail veers to the east beneath Tapeats Sandstone cliffs near the 6.34 mile mark (Map 1A.2.2), the rock darkens considerably and takes on the vertical foliation characteristic of schist (Figure 1A.2.21).  Here, the Bright Angel Fault occupies the V-notch carved by a small tributary to Pipe Creek; the abrupt change from granitic rocks of the Pipe Creek Pluton indicates that you have crossed the Bright Angel Fault and are now treading on Brahma Schist.  As we saw from Plateau Point, these oldest rocks of the Grand Canyon Metamorphic Suite are exposed throughout the upper drainage and eastern wall of Pipe Creek’s inner canyon.

Figure 1A.2.18 Garden Creek cuts a narrow defile through granitic crystalline basement along the Bright Angel Trail copyrighted

Figure 1A.2.20.  Garden Creek disappears through a narrow defile cut into granitic crystalline basement where the Bright Angel Trail crosses from Garden Canyon into Pipe Creek Canyon.

Figure 1A.2.19 Pipe Creek Pluton and Brahma Schist in fault contact on the Bright Angel Trail copyrighted

Figure 1A.2.21.  Granitic rock of the Pipe Creek Pluton lies in fault contact with dark, foliated metamorphic rock of the Brahma Schist on the Bright Angel Trail, the soaring cliffs of the South Rim rising to Yavapai Point offering a spectacular backdrop.

From the V-notch, the Bright Angel Trail zig-zags down through Brahma Schist to reach the dry wash of Pipe Creek at 6.92 miles (Map 1A.2.2).  The trail now follows the stream bed, crossing and recrossing the channel on its way to the Colorado River.  More evidence of faulting is marvelously expressed along a stretch of the channel beginning at 7.28 miles (Map 1A.2.2), where Bright Angel Trail navigates to the left and then right, following a bend in the stream bed as it passes around a resistant knob of Brahma Schist.  When you reach the downchannel side of the bend, examine the pinkish granite of the Pipe Creek Pluton on the opposite wall of the canyon; Pipe Creek has exploited the zone of weakness created by the Bright Angel Fault and its channel runs directly along the fault trace here.  Ahead, the trail passes Garden Creek entering the canyon from the left at 7.40 miles, and Pipe Creek becomes a permanent stream.  Near 7.63 miles (Map 1A.2.2), the inner canyon of Pipe Creek become more constricted as it leaves granitic rocks of the Pipe Creek Pluton and enters a narrow defile cut through Vishnu Schist.  But first, turn around, the wide inner canyon behind you offer great views all the way to the South Rim.  To your right (looking upcanyon), the crystalline basement here is overlain by a Tapeats Sandstone promontory; this is Plateau Point from the bottom up (Figure 1A.2.22).

Figure 1A.2.20 Plateau Point from the bed of Pipe Creek copyrighted

Figure 1A.2.22.  The Tapeats Sandstone promontory of Plateau Point from the bed of Pipe Creek.

Continue down canyon, polished outcrops of folded Vishnu Schist intruded by cross-cutting stringers of Zoroaster Granite, themselves intensely folded, abound along the channel of Pipe Creek (Figure 1A.2.23).  A few more twists and turns in the trail eventually brings you to the River Resthouse at 7.95 miles (Map 1A.2.2), a rock pavilion on the opposite side of the creek.  The shelter provides shade and an emergency phone, but no running water (filterable water literally lies at your feet); you also get a good view straight down Pipe Creek to the Colorado.  In just over 100 yards, you reach a signed trail junction and the official end of the Bright Angel Trail.  The main trail heads to the right, which now becomes the River Trail (toilets are available just ahead).  Before taking your final steps on this trail to Bright Angel Campground, Phantom Ranch, or the junction with the South Kaibab Trail, you may want to trundle down the short 200 yard path of the left fork which brings you to Pipe Creek beach on the Colorado River.  It may seem odd, but this location affords the only river access on the River Trail.  Pipe Creek beach offers some fine wading in the icy waters of the Colorado (do not risk swimming in the Colorado, no matter your level of competence), but just up from the beach are several fine outcrops of Vishnu Schist that have been scoured, scalloped, and polished by the sediment-laden flood waters of the Colorado River in times past.  Figure 1A.2.24 displays a very nice example of a “pothole” (occupied by one of my former students); potholes form when the swirling waters of a high-energy stream carrying coarse particles of sand and gravel act much like a drill bit, boring a hole downward into the rock over time.  Don’t terry by the river too long, it heats up quickly within the inner gorge of the Grand Canyon (especially if you mean to return to the South Rim all in one day).

Figure 1A.2.21 Pink Zoroaster Granite intrusives in dark Vishnu Schist in the channel of Pipe Creek copyrighted

Figure 1A.2.23.  Polished outcrops of folded Vishnu Schist intruded by cross-cutting stringers of Zoroaster Granite, which have themselves become intensely folded are common along the channel of lower Pipe Creek.

Figure 1A.2.22 Scoured bedrock outcrops and potholes near Pipe Creek Beach copyrighted

Figure 1A.2.23.  A pothole drilled into an outcrop of Vishnu Schist by the swirling, sediment-laden flood waters of the Colorado River at Pipe Creek beach, modeled by a former student for of mine.

Back on the main route, it is now time to tackle the River Trail; my description of this trail continues from where the Bright Angel Trail ends, at roughly 7.98 miles (Map 1A.2.2), joining them into a single route.  Head right at the signed trail junction. The River Trail hugs the right (south) bank of the Colorado all the way to its junction with the South Kaibab Trail, offering many spectacular views along Upper Granite Gorge as it alternates between sections carved from naked stone, to bouldery rockfalls and alluvial fans, and even sections plowing through modern sand dune deposits.  The trail provides access for people, but it serves another purpose too.  The Trans-canyon pipeline, carrying the South Rim’s water supply from its Roaring Springs source high in Bright Angel Canyon, underlies much of the trail before heading up the cliffs of the inner gorge to the Tonto Platform near Plateau Point.  Your tread quickly climbs high above the river on a trail blasted through Vishnu Schist by the Civilian Conservation Corps back in 1933.  Towering cliffs of dark Vishnu Schist, shot through by ribbons of light-colored Zoroaster Granite close in on both sides of the river, rising a thousand feet or more.  Layers of darkly weathered Bass Limestone, reddish Hakatai Shale, and buff-colored Shinomo Sandstone, the lower Unkar Group of the Late Proterozoic Grand Canyon Supergroup, adorn the upper cliffs north of the river.

At 8.55 miles (Map 1A.2.2), the trail crosses a major gully entering from the right and leaves the crystalline basement too begin a slog through modern dune sands blown up against the base of the cliffs.  In a little more than one-tenth of a mile, the River Trail passes on to the rubbly deposits of a steeply sloping alluvial fan, blanketed in places by sand.  Alluvial fans form at the mouth of a canyon, where a rapid change from a high to low gradient channel causes an equally rapid loss of stream transport energy; the sediment load of a typically flashy, high-energy desert stream such as this one is quickly deposited as a fan- or lobate-shaped accumulation of sand, gravel, and boulders spreading outward and downward toward the river bank.  The trail contours of the fan slope remaining at the same elevation, and near 8.82 miles (Map 1A.2.2), it passes back onto sand dune deposits.  The bottom of the gorge has gradually widened as you progressed up canyon, and the view before you now takes in a broader perspective, bringing the lower portion of the Paleozoic sedimentary rock sequence into view on the north side of the river, crowned by the iconic Zoroaster Temple (Figure 1A.2.25).  In the middleground, the Silver Bridge spans the Colorado River, providing access to the North Kaibab Trail and North Rim.  The sandy deposits at your feet, combined with the warmth of the inner gorge, provide good habitat for Mohave Desert plants.  These ideal conditions have allowed plants such as the yucca to migrate up canyon along the river corridor, well beyond their normal Basin and Range biome.  As you press on toward the bridge, be sure to look across the river to your left.  The Grand Canyon Supergroup rocks observed earlier exhibit down-to-the-west tilting and multiple offsets along normal faults that dip upriver toward Bright Angel Canyon (Figure 1A.2.26).  The deformation here is related to growth of a small graben along the Bright Angel Fault described earlier at Plateau Point.  Recall that extensional motion on the main fault caused a large crustal slab to tilt downward toward the northeast, while a smaller slab rotated back into the main fault from the west.  Now you are observing that package of deformed rocks up close.  The smaller slab was fractured into several blocks that where rotated down and to the east into the main fault zone along multiple, minor fault splays paralleling the main Bright Angel Fault, thus tilting the normally horizontal sedimentary rock layers down toward the west. Each minor fault also offset the formations relative to each other and even the crystalline basement; at least four normal faults occur in Figure 1A.2.26, with the greatest offset on the fault furthest down river.

Figure 1A.2.23 The Silver Bridge over the Colorado River copyrighted

Figure 1A.2.25.  Where the inner gorge widens, the River Trail briefly accommodates views of the upper walls of the Grand Canyon; the Silver Bridge spanning the Colorado River to access Bright Angel Campground and Phantom Ranch lies in the middleground, while the yuccas growing on sand dune deposits to the fore indicate an upcanyon migration of Mojave Desert vegetation.

Figure 1A.2.24 Normal-faulted Supergroup rocks associated with the Bright Angel Fault copyrighted

Figure 1A.2.26.  Deformation of Supergroup rocks is readily observed along the River Trail just south of the Silver Bridge, here the rock layers are titled down-to-the-west and offset by several minor normal faults associated with extensional motion on the Bright Angel Fault about 650 million years ago.

After another slog over a short section of hot, sandy trail (be aware that this can be brutal in the afternoon, plan accordingly), you return to crystalline basement rock once again.  Shortly, you meet the Silver Bridge coming in from the left at 9.04 miles (Map 1A.2.2).  Crossing the bridge will bring you to the North Kaibab Trail, and if Bright Angel Campground or Phantom Ranch is your goal, shade, water, and food lay only about three-tenths of a mile away.  Be sure to pause on the bridge as you cross, especially if you are lucky enough to pass at sunrise (Figure 1A.2.27), the view downriver is quite enduring.  The view here nicely displays the contrasting composition of north and south walls of the inner gorge.  On the right (north) side of the river, faulted Supergroup rocks are stacked on Vishnu Schist, but on the left (south) side, the Vishnu rises all the way to the brownish Tapeats Sandstone cap at the lip of Upper Granite Gorge.  Vishnu foliation is oriented upriver toward you, and the south wall of the gorge exhibits numerous ribbon-like granitic intrusives penetrating along foliation within the schist.  After crossing, veer right on the main trail and navigate your way past the corrals, sewage treatment facility, and the hikers toilets to an aluminum bridge over Bright Angel Creek.  A trail to the left here takes you into Bright Angel Campground, but if you are hiking on to Phantom Ranch or joining the North Kaibab or South Kaibab Trails, cross the bridge.  My description of the Bright Angel Trail ends on the far side of this bridge at 9.40 miles (Map 1A.2.2).  Hiking to the left at this juncture merges you with the North Kaibab Trail and quickly brings you to Phantom Ranch; hiking to the right, you join the South Kaibab Trail and soon cross the Black Bridge over the Colorado, upriver of Bright Angel Creek, to begin a steep hike out of the canyon.

Figure 1A.2.25 Downcanyon sunrise from the Silver Bridge, Bright Angel Trail copyrighted

Figure 1A.2.27.  The view down river at sunrise from the Silver Bridge on the Bright Angel Trail.

On the other hand, if you intend to join the South Kaibab Trail, your easiest path is to continue straight ahead at the bridge juncture on the River Trail.  The trail remains on Vishnu Schist all the way to its end, climbing gradually higher above the Colorado on another section of trail torn from the cliff face.  It offers superb views of the inner gorge on north side of the river and the mouth of Bright Angel Canyon.  In about half a mile, at 9.61 miles (Map 1A.2.2), the River Trail passes a small outcrop protruding from the cliff face, and shortly beyond, the trail passes two gorgeous granitic dikes intruding the Vishnu Schist parallel to its foliation (Figure 1A.2.28).  Here, the foliation nearly parallels the course of the river, rather than the river running more generally counter to it and the dikes are well exposed.  Just ahead, the trail bends right.  Be sure to look back across the river to the northwest; here the River Trail offers up perhaps its prettiest view, the mouth of Bright Angel Canyon and the delta of Bright Angel Creek protruding well into the Colorado (Figure 1A.2.29).  The delta forms an ideal crescentic shape and its size relative to that of Bright Angel Creek, and its preservation of channel migration and abandonment features, suggests that the stream must occasionally carry a considerable sediment load, usually in the form of late summer flash floods.  Growth of the delta has pushed the Colorado River channel against the south wall of the gorge where it has likely stayed for as long as the creek has been actively downcutting its valley.  A short walk later, you reach another signed trail junction and the end of the River Trail at 9.77 miles.  From the trail junction you have two options, descend the South Kaibab Trail to the river, cross the Black Bridge, and join the North Kaibab Trail (most likely to your lodgings at either Phantom Ranch or Bright Angel Campground); or begin your ascent of the South Kaibab Trail all the way to the rim (I hope you started your rim-to-river-to-rim hike rather early).

Figure 1A.2.25 Granitic dikes intruding parallel to foliation in the Vishnu Schist copyrighted

Figure 1A.2.28.  Near the upcanyon (northern) terminus of the River Trail, a beautiful pair of granitic dikes intrudes the Vishnu Schist parallel to its foliation.

Figure 1A.2.26 The mouth of Bright Angel Canyon and the Bright Angel Creek delta copyrighted

Figure 1A.2.29.  The mouth of Bright Angel Canyon and the delta of Bright Angel Creek; the stream carries large loads of coarse debris during infrequent flash floods, providing enough material to the delta to allow its outward growth into the much larger Colorado River.

Hiking Trail Maps

Map 1A.2.1.  Shaded-relief map of the northeast quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

Map 1A.2.2.  Shaded-relief map of the northwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.

Hermit Trail (Tr1A.3)

 In the annals of the history of human interactions with the Grand Canyon, especially since its “discovery” by settlers of European descent, the Hermit Creek basin was witness to one of the most aggressive efforts to promote, develop, and capitalize on the canyon’s incredible scenic beauty.  “Improvements” within the basin began with Louis D. Boucher, the “hermit” of Hermit Creek basin who arrived at the Grand Canyon in 1891 and lived in the area for nearly 20 years.  Boucher helped construct the Waldron Trail into the upper basin in 1896 and then built his own Silver Bell Trail around 1902 (later renamed the Boucher Trail) to access his seasonal residences and entertain clients at Dripping Springs and on lower Boucher Creek. The Boucher (Silver Bell) Trail diverges west from the modern Hermit Trail in upper Hermit Canyon, drops into upper Mineral Canyon, and then crosses a drainage divide into lower Boucher Canyon.  Later, in 1911, the Santa Fe Railroad bought out Boucher’s interests and initiated a development program that involved much infrastructure on the rim, but also included the construction of the West Rim Road (Hermit Road) to Hermit’s Rest, and their own Hermit Trail, at the time, the most state of the art rim-to-river trail in existence.  The Hermit Trail was built to provide easy access and quick service to “Hermit Camp”, a luxury campsite near Hermit Creek.  Hermit Camp predated Phantom Ranch (in Bright Angel Canyon) by 10 years; although operations ceased in 1930, according to the National Park Service, “for two decades Hermit Camp was the last word in gracious tourism below the rim”.  At its peak, the camp included a tramway from Pima Point for easy movement of supplies, telephone service, a functional automobile for transporting guests and gear short distances within the facility, and it even boasted a Fred Harvey chef.

The passage of time has allowed erosion on the canyon’s steep, unstable slopes to take a heavy toll on the original Hermit Trail, but despite its roughened condition and lack of routine park maintenance, this trail is ideally suited for experienced, knowledgeable canyon backpackers looking for the greater solitude that Grand Canyon’s “Corridor” trails just can’t provide.  The Hermit Trail begins near Hermit’s Rest, overlooking the Hermit Creek basin, the upper portion of Hermit Canyon which has been eroded far back into the Grand Canyon’s South Rim.  The basin is underlain by the Hermit Formation; its mudstones formed an inherently weak defense to weathering and erosion such that rapid backwasting of the overlying cliffs of Coconino Sandstone has opened a broad amphitheater here.  The upper section of the Hermit Trail sustains a steep descent to the floor of the Hermit Creek basin, dropping a couple thousand vertical feet in the first two and a half miles.  This part of the trail passes through the upper portion of the Paleozoic strata so marvelously exposed in the Grand Canyon, including the Kaibab Limestone, Toroweap Formation, Coconino Sandstone, and Hermit Formation, zig-zagging downward through cliffs and slopes formed of alternating resistant and nonresistant rock types.  Passage through the Kaibab and Coconino Formations is particularly speedy via well-defined switchbacks.  Most of the Hermit Trail was originally surfaced with large, laboriously hand-fitted rock slabs that created a smooth, paved walking surface.  Ongoing mass wasting processes have undone much of this remarkable work, but a few isolated fragments survive, especially in the Coconino section of the trail.

Evidence of past life is well preserved in the Kaibab and Coconino units.  As you are warming up for your long trek on the Hermit Trail, be sure to look carefully for fossilized brachiopods, crinoids, corals, bryozoans, and sponges in the Kaibab Limestone; these invertebrates populated the shallow, tropical seas covering western North America about 260 million years ago in which the limestone beds accumulated.  The Coconino Sandstone, on the other hand, preserves a superb array of trace fossils within its sandy beds.  As you struggle through the Coconino’s tortuously steep section of trail, take a few moments to contemplate these fossilized tracks more closely.  They indicate the passage of terrestrial, desert-dwelling animals of 270 million years ago, and include lizards and amphibians, scorpions, millipedes, and spiders.  Some tracks are mere smudges, but others are exquisitely detailed, retaining pad and claw marks on trackways more than a dozen prints long.  Prints in the Coconino Sandstone have been noted in many canyon locations, but they were first studied in detail along the Hermit Trail, where they are particularly abundant and well-preserved, in some cases easily visible without even stepping off trail.  Geologists have determined that their remarkable preservation was probably caused by animals crossing dampened sand just prior to its rapid burial by another layer of wind-blown sediment.  The Coconino Sandstone formed in a vast desert erg abutting the coastline of a long ago Permian sea; it is likely that periodic coastal fogs rolled over the sand dunes now found in the Grand Canyon area, wetting the dune sand in a fashion similar to present-day conditions in the coastal deserts of the Atacama in South America, and the Namib in Africa.

Once past the distinctive break in slope below the Coconino Sandstone, the trail saunters on down through the Hermit Creek basin, gradually descending past the junction for the infrequently used Waldron Trail not far from the Coconino-Hermit contact, and the Dripping Springs Trail near the top of the Supai Group.  Take the right fork at each location to maintain course on the Hermit Trail and eventually, your tread crosses the massive sandstone cliff-band of the reddish-brown Esplande Sandstone, right where you drop into the Hermit Creek gorge.  Soon after, the trail passes Santa Maria Spring and the welcoming shade of its masonry shelter, a vestige of the original Hermit Trail.  The spring is not considered permanent by the park service, but there is usually always a trickle of water, and reasonably good flow in the spring hiking season (but don’t forget to filter it!).  At this point, the Hermit Trail begins a long, grindingly slow traverse of the remaining three formations in the Supai Group, the classic “Supai Traverse” of many rim-to-river trails.  Your route through this section generally contours along the eastern side of Hermit Canyon following bedding contacts, and is characterized by long stretches of gently undulating trail connected by short, sharp descents.  The trail parallels an angle of repose slope, crossing high gradient drainages tributary to Hermit Creek at roughly perpendicular intersections.  As a consequence, the Supai traverse of the Hermit Trail has been badly damaged by several significant landslides.  You will need to scramble across chaotic piles of rubble that has washed down or fallen from above many times during the transit of gullies.  Pay attention at these crossings; even experienced hikers can lose the trail entirely where debris has covered the original route.  Although rock cairns stacked by previous hikers can often be helpful as trail markers, be aware that the cairns are only as good as the route-finder’s skill.  After passing Lookout Point, the trail contours in and out of three successive tributaries where the mass wasting problem is especially true.  The worst of these detours around a much-maligned segment of trail occurs on the far side of the last tributary, near the Supai-Redwall contact just west of Cathedral Stairs.  Here, a breakdown slope created by faulting and weakening of Supai layers above, is covered in lose landslide debris difficult to navigate.

The descent becomes unrelenting at the Cathedral Stairs. A series of short, sharp, rocky switchbacks initially greets hikers already weary from their Supai traverse, leading through yet another fault-controlled breakdown slope in the Redwall Limestone.  Exiting the Redwall, the trail becomes one long straightaway as in descends a rubble-strewn slope in the Muav Limestone below Cope Butte.  A last series of switchbacks takes you through the Bright Angel Shale to the Hermit Trail’s intersection with the Tonto Trail.  This last section of the Hermit is in the full sun by mid-morning and dangerously hot by mid-afternoon; it is also strewn with small, rounded chunks of rubble that just love to roll beneath your ankles, so watch your step!  The Tonto Trail is an important transcanyon route that allows access in both directions, east to Monument Creek and west to Hermit Creek.  The original Hermit Trail made a left turn here, following the course of the modern Tonto Trail about a mile to “Hermit Camp” just above the modern Hermit Creek campsite.  Near the old camp, a trail descends cliffs in the upper layers of the Tapeats Sandstone to the bed of Hermit Creek just upstream of a wonderful little gorge carved through the remaining Tapeats.  The original Hermit Trail then continued about another mile and a half to the Colorado River and Hermit Rapids.  Little of the original trail construction shows once the Hermit emerges from the Tapeats gorge and crosses into the Vishnu basement; today the lower section of this once impressive trail is mostly a foot path winding along the banks of Hermit Creeks, now and again using the stream bed itself.  Eventually, you’ll find yourself at Hermit Rapids, which is a big one, and well worth the trip if time and energy allows.  My description of the Hermit Trail ends at the Hermit Trail-Tonto Trail junction, if you are continuing to the Hermit Creek campsite and sights beyond, pick up the description of the Tonto Trail under my hiking trail option entitled “Tonto Trail (Hermit Trail Junction to Boucher Trail Junction – Tr1A.5c)”; if the opposite direction and Monument Creek campsite is your destination, join the east bound Tonto under my hiking trail option entitled “Tonto Trail (Indian Garden to Hermit Trail Junction – Tr1A.5b)”.

The Hermit trailhead is located near Hermit’s Rest, a short walk beyond the last stop on the Red Route, one of the park’s free shuttle options on the South Rim (Stop #10 on Map 1A.3 and Map 1A.3.1). Day-hikers can walk over to the Village Route Transfer Station to hop aboard the Red Route (Stop #1 on Map 1A.2) from their vehicles parked at the Backcountry Information Center, from nearby rim hotels, or from the Hermits Route Transfer Station on the Blue Route (Stop #6 on Map 1A.2).  However, backpackers may find the parking area at the trailhead a much easier marshalling point.  According to the park service, “a numerical code is required to open the gate giving access to the Hermit Road at the Hermit Transfer”.  The keypad used to enter this code is mounted on the steel post that supports the swinging arm of the gate.  From April through October, “backpackers with a valid backcountry permit for the Hermit Trail can drive 8 miles west along Hermit Road to Hermits Rest, then continue beyond the end of the pavement on the dirt road ¼ mile to the trailhead.”, but note that during the winter the Hermit Road is open to all vehicles and no code is required for access.  The Hermit Trail is the natural entry route for an backpacking excursions into Hermit Creek or Monument Creek Canyons.  If you plan to camp below the rim, the park service indicates that the only legal places to camp within the Hermit Creek drainage are the designated campsites at Hermit Creek and Hermit Rapids, this is likewise true of the Monument Creek drainage where camping is permitted at Monument Creek and Granite Rapids only.  The hike down the Hermit Trail reaches the Tonto Trail junction in seven miles, and from there, it is just over a mile to the Hermit Creek campsite or about two and a quarter miles to the Monument Creek campsite; for experienced hikers, both destinations take roughly 4-6 hours to reach, but Monument Creek is obviously the longer of the two goals.  I don’t recommend hiking all the way to the river campsites in one day, but if you plan to do so, add another mile and a half and an hour’s time to your respective treks.

Most rim-to-river trails in the Grand Canyon begin with a bang; a rapid descent through cliffs of the Kaibab Limestone, but the Hermit Trail starts in a rather unassuming way.  From the trailhead, you begin with a gradual drop into a small valley tributary to Hermit Creek Canyon through ledgy outcrops of the Kaibab stained by the rusty hues of oxidized minerals precipitated from groundwater solutions that once circulating along the nearby Hermit Fault.  Near 0.23 miles (Map 1A.3.1), the trail makes a right-angle bend, temporarily paralleling the small valley as it continues its gentle descent.  Here, the bench-like limestone outcrops, especially on the right-hand, upslope side of the trail expose resistant chert nodules that protrude in base relief from the softer limestone; the nodules contain a myriad of fossils.  The cherty lumps display tube-shaped sponge spicules (the hard parts of a sponge), brachiopods that form D-shaped, bivalved, clam-like creatures, crinoids that appear as small disks and segmented tubes, bryozoans forming colonial structures that look like porous twigs and cookies, and horn corals that resemble miniature cattle horns.  Not to detract from your intended hike, but this location is one of the best fossiliferous zones in the Kaibab Limestone along any of the Grand Canyon’s trails.  It is worth spending some time poking around, but you may want to return at a later time when you are not encumbered by a heavy load.  The fossils here are representative of the life teeming in the 260 million-year-old, warm, shallow seas of the open, passive marginal shelf environment that once covered this region in the Permian (Figure 1.4).

Shortly, the Hermit Trails bends to the right (north) and begins a more earnest descent into the canyon along a series of switchbacks; this section of trail offers several fine views into the depths of Hermit Canyon (Figure 1A.3.1).  A large block of Kaibab Limestone adorned with six drill holes rests in the trail at 0.38 miles (Map 1A.3.1), marking the limestone unit’s contact with the Toroweap Formation.  The transition is fairly abrupt, changing from thick, resistant beds of gray limestone to weak, red-brown mudstones.  The trail’s gradient changes too, as you enter a southwesterly trending section comprised of flat traverses connected by short, somewhat steeper segments.  The Toroweap is less resistant to weathering and erosion and its sloping-forming nature stands out here.  As you descend, note that the mudstone layers are often contorted by the upward flow of soft evaporite minerals such as gypsum and halite precipitated from the briny waters of an arid coastline about 265 million years ago (Figure 1.4).  Intervening muds buried and pressed down on the low density evaporites, squeezing them laterally and injecting them up into overlying layers.  Gradually, the trail extends southward, back into the Hermit basin, providing gorgeous views across the valley to the reentrant canyon formed by the Dripping Spring tributary (Figure 1A.3.2).  This tributary has formed at least in part by a process called groundwater sapping (a process not uncommon to the Grand Canyon).  In this case, water percolating down through more porous rock layers above is forced to flow laterally when it reaches the less permeable mudrocks of the Hermit Formation.  Lateral groundwater flow meets the slopes of Hermit Canyon and returns to the surface as a spring – Dripping Spring.  The concentrated flow of water erodes the weaker Hermit shales out from under the overlying Coconino Sandstone above, causing sections of the cliffs to break away and the valley head gradually retreats by backwasting over time.  The Dripping Spring tributary is also aligned with the Eremita Monocline, and folding of the sedimentary rocks may have created a zone of weakness here that is being exploited by the forces of erosion.

figure-1a-3-1-hermit-canyon-sunrise-hermit-trail-copyrighted

Figure 1A.3.1.  Hermit Creek Canyon on a sunrise hike near the top of the Hermit Trail.

figure-1a-3-2-dripping-spring-canyon-on-the-west-side-of-the-hermit-basincopyrighted

Figure 1A.3.2.  Dripping Springs Canyon, a tributary reentrant cut back into the Hermit Creek basin at the upper end of Hermit Creek Canyon.

The Toroweap Formation changes compositionally with depth and more durable limestones begin to dominate its lower reaches.  Here, the trail steepens and presents another series of switchbacks.  Limestones are typically associated with deeper water deposition on the more distal portion of a continental shelf, an indication that marine environments gradually retreated as the Toroweap accumulated.  A left-hand switchback at 0.86 miles marks the contact between the Toroweap Formation and the Coconino Sandstone (Map 1A.3.1).  The transition is quite obvious as massive brownish limestones are replaced by the fine, whitish sands of the Coconino.  Below this contact, the tread of the Hermit Trail becomes paved in flagstones of Coconino Sandstone.  As you drop through this incredibly steep section of trail, take a moment to ponder the intense labor required to build it, an enduring legacy to a trail now more than 100 years old.

Through this portion of the Hermit Trail, the tread was often constructed directly on bedding planes within the Coconino Sandstone (Figure 1A.3.3), beds that dip at an angle of roughly 20-30º, the angle of repose of the fine sand of which it is comprised.  Here, you are walking on 270 million-year-old mega-scale crossbedding formed by sand dune migration across a gigantic desert erg the size of the modern Sahara.  Cross-beds such as these form when sand is blown up the gentle back, or stoss, side of the dune to gather at the crest, where it accumulates as an over-steepened, unstable mass that periodically cascades down the front, or lee side of the dune, eventually coming to rest at its rather steep angle of repose.  The thin layers of sandstone observed in outcrop here were formed as individual avalanches of sand repeatedly poured down the steep, lee-side face of the advancing dune.  The flat to gently curved surfaces that can often be seen to truncate crossbedding represent wind deflation in the hollow on the upwind side of the dune.  These features are called bounding surfaces; a single package of cross-beds is thus bounded by two of these truncations, forming that portion of the dune that was not removed by subsequent erosion before the next dune migrated past.

figure-1a-3-3-megacrossbedding-in-the-coconino-sandstone-copyrighted

Figure 1A.3.3.  The Hermit Trail descends through the Coconino Sandstone on the backs of ancient sand dunes, a former student of mine stands on bedding plane surfaces accumulated at the angle of repose of the dune’s constituent particles deposited on the lee, or downwind dune face during its migration.

As described in the introduction to the Hermit Trail, bedding plane surfaces in the Coconino preserve excellent trace fossils of ancient vertebrates that once roamed the Permian age, coastal desert erg (Figure 1A.3.4); be on the lookout, many are visible without even stepping off trail!  The superb preservation is believed to have been the result of small animals such as lizards and scorpions that crossed dampened sand on the lee face of dunes just prior to burial by yet another sandy cascade.  Prevailing theory suggests that periodic coastal fogs rolled over the sand dunes, wetting the dune sand in a fashion similar to the modern coastal deserts of the Atacama in South America, and the Namib in Africa.  After traversing a lengthy stretch of cobblestone-paved, southwest-trending straightaway, you reach a right-hand switchback at 1.18 miles (Map 1A.3.1).  About 20 yards short of the bend, you pass a set of rock steps angled roughly perpendicular to the trail, steps that seem to go nowhere.  From these steps to the right-hand bend, bedding surfaces in the Coconino Sandstone contain the highest concentration of trackways yet discovered in the park; ten sets of tracks made by animals from the size of mice to kittens.  Figure 1A.3.4a shows part of a trackway made by a lizard-like animal much like the present-day lizards you have probably seen skittering about; these tracks retain pad, toe, and claw marks and are wonderfully detailed.  Figure 1A.3.4b displays the trackway of a larger animal, perhaps the size of a large modern-day iguana you’d find in a pet store; these tracks pressed down into loose sand as the animal dragged a long tail behind.  More tracks await the careful observer; another concentration occurs about two-tenths of a mile down trail near the base of the Coconino.  Look for them about 10 yards shy of a right-hand switchback, the last in a series of six.  As the sun rises higher during your descent, be sure to take in the expansive views of Hermit basin; the stair-stepped layers of Kaibab Limestone cliffs on Toroweap Formation slopes, Toroweap on Coconino Sandstone cliffs, Coconino on Hermit Formation slopes, and Hermit on Esplanade Sandstone cliffs are also on obvious display (Figure 1A.3.5).  A by-product of the differential erosion of resistant and weak rock layers, this alternating pattern of cliff-slope-cliff-slope is characteristic of the entire Paleozoic sedimentary rock sequence.  Experienced Grand Canyon hikers keep a mental record of the units they have passed through in this way and can approximate their vertical position within the canyon quite accurately.

figure-1a-3-4-vertebrate-animal-fossils-in-the-coconino-sandstone-copyrighted

Figure 1A.3.4.  Exquisitely preserved vertebrate trace fossils, probably the ancient trackways of small, desert-dwelling animals such as lizards and scorpions, famously criss-cross the bedding plane surfaces of the Coconino Sandstone along the Hermit Trail.

figure-1a-3-5-upper-paleozoic-rock-units-on-the-west-side-of-the-hermit-basin-copyrighted

Figure 1A.3.5  The cliffs and slopes formed by differential erosion of alternately resistant and weak layers of sedimentary rock comprising the upper Paleozoic sequence in the Grand Canyon.

Once past this latter group of tracks, a short descent brings a big change in rock composition from crossbedded quartz sandstone to brick-red mudstone as you reach the Coconino Sandstone – Hermit Formation contact at 1.33 miles (Map 1A.3.1).  The mudrocks of the Hermit accumulated in meandering stream systems and deltas along a low gradient coastline 280 million years ago (Figure 1.4).  Plant fossils discovered in the Hermit attest to a warm, moist climate quite different than that associated with the Coconino; the abrupt change in conditions easily recognized by a brief examination of your trailside contact (Figure 1A.3.6).  Here, the red mudstone at the top of the Hermit appears to be chemically altered, forming a greenish-gray paleosol; and the presence of large, sand-filled fractures indicates rapid drying and inundation by migrating sand dunes.  Below the contact, the trail’s gradient becomes more moderate as it meanders down into the broad, gentle valley of Hermit basin; the basin itself a by-product of rapid erosion of the weak mudrocks of the Hermit Formation.  Before you, an impressive cliff of Coconino Sandstone on the basin’s western side provides perspective by prominently displays its characteristic mega-scale crossbedding at distant where the entire thickness of the unit can be observed (Figure 1A.3.7).  As the trail flattens out on the valley floor, you pass the Waldron Trail merging from the left at 1.44 miles and the Boucher/Dripping Spring Trail diverging to the left at 1.76 miles (Map 1A.3.1).

figure-1a-3-6-coconino-hermit-contact-hermit-trail-copyrighted

Figure 1A.3.6.  The Coconino-Hermit contact; marked by the abrupt change from crossbedded, quartz sandstones to brick-red mudstones (A), the mudstone marred by large desiccation cracks produced by intense drying, immediately followed by rapid burial during the passage of migrating sand dunes (B).

figure-1a-3-7-megacrossbedding-in-the-coconino-sandstone-copyrighted

Figure 1A.3.7.  A cliff of Coconino Sandstone in the western wall of the Hermit Basin prominently displays its  mega-scale crossbedding, a sedimentary structure associated with sand dune migration across a vast desert erg.

This second trail junction also marks the contact between the soft mudstones of the Hermit Formation and the denser sandstones of the Esplanade Sandstone, the uppermost formation in the Supai Group.  Sticking to the right fork, in just a few hundred feet, the trail navigates through several outcrops of massive sandstone at the top of the Esplanade to offer an eye-catching view down Hermit Canyon at the lip of a pouroff.  The tight confines of the canyon here are the result of Hermit wash initially cutting through thick sandstones in the upper Esplande.  Shortly, the trail switchbacks to the right and descends passed an outcrop of deep red, thinly bedded mudstones exhibiting distinctive mudcracks.  Careful examination of the outcrop reveals that the thin beds of mudstone curve upward to the left (south) against a sculpted surface of massive sandstone.  After winding through the bed of Hermit wash, the trail hugs the face of an overarching Esplande cliff.  This location offers a good opportunity to look across the wash to the outcrop you just passed through, and now it becomes clear that the curved sandstone surface was the edge of a channel sculpted by running water into what was likely soft sand at the time, and later back-filled with muddy sediments (Figure 1A.3.8a).  The thin mudstones that you observed to curve upward against the sandstone lap successively onto the widening margin of the channel (Figure 1A.3.8b).  Back on your side of the wash, the trail traverses an alcove in the overhanging cliff; its back wall is comprised of alternating thick, massive sandstones and thin mudstones.  At the top of several mudstone layers, polygonal mudcracks appear in cross-section (Figure 1A.3.9).  The combination of outcrops you have just passed are indicative of the Supai Group’s multifaceted origins; many geologists interpreting that its deposition occurred on a broad coastal plain associated with a passive continental margin, with individual settings ranging from shallow marine to continental depending on rapidly fluctuating sea levels.  Layers within the group’s four rock units probably formed from a compilation of desert, fluvial, deltaic, beach, and estuarine or even shallow-marine origins, but was likely dominated by eolian dunes occupying a coastal-plain setting.  At this location, the outcrops appear to exhibit massive shore dune, beach or nearshore sands and tidal flat or floodplain muds, cut by a stream or tidal channel that eventually filled with mudstones.  The presence of mudcracks is suggestive of aridity and periodic drying which could be related to tidal fluctuations, variations in stream flow, or occasional flooding.

figure-1a-3-8-tidal-channel-in-the-upper-esplanade-sandstone-hermit-trail-copyrighted

Figure 1A.3.8.  An outcrop in the Esplanade Sandstone displays a possible mudstone-filled tidal channel or stream channel cut into shore dune, beach, or nearshore sands (A); the arrow indicates the location of the channel margin cut into massive sandstone and onlapping mudstone fill depicted in (B).

figure-1a-3-9-mudstone-interbed-exhibiting-mudcracks-in-the-esplanade-sandstone-copyrighted

Figure 1A.3.9.  A mudstone interbed within the Esplanade Sandstone exhibits polygonal mudcracks suggesting periodic subaerial exposure to arid conditions.

Upper Hermit Canyon abruptly widens and the trail makes another rapid descent through the remainder of the Esplanade Sandstone.  As you drop through several thick cliff-bands on a series of short switchbacks, the trail approaches Santa Maria Spring and its Santa Fe Railway era stone rest house at 2.32 miles from the trailhead (Map 1A.3.1).  The spring issues from the slope just below the contact between the Esplanade Sandstone and the Wescogame Formation (Figure 1A.3.10).  Its location may in part be controlled by the nearby Hermit Fault which has fractured the rocks and opened up avenues for percolating groundwater, although the control is likely stratigraphic, as the mudstone-dominated Wescogame presumably forces groundwater that is migrating downward through overlying, more permeable layers to flow laterally on to the slope here where it encounters less permeable mudrocks.  Santa Maria Spring is perennial, but its flow is best in the spring hiking season and is reduced to a trickle by autumn; the shady interior of the rock shelter does offer a pleasant break from the sun, particularly for hikers climbing out of the canyon who often reach this stop by the time the sun reaches this part of the canyon in late morning.  This location is an ideal turn-around point if a day-hike was in your plans.

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Figure 1A.3.10.  Santa Maria Spring and its Santa Fe Railway-built rock shelter; the spring issues from the slope on the near side of the shelter, just below the contact between the cliff-bands of sandstone in the Esplanade Sandstone and the mudrocks of the Wescogame Formation.

If you have taken the luxury of a rest break at the Santa Maria Spring rock shelter, don’t terry long; it is still a long backpack to your campsite.  Fortunately (or not, depending on your perspective), from here, the Hermit trail begins a nearly three-mile-long traverse of the remaining Supai Group, managing only a few short, steep drops along the way.  This is a particularly lengthy version of the “Supai Traverse”, unavoidable on all rim-to-river trails.  At first, the trail contours around a series of small points and passes in and out of several minor washes as it gradually trends northwest parallel to the deepening canyon.  A splay of the Hermit Fault passes near the trail here which has fractured the sandstones of the Supai Group and left evidence of its motions in the form of white, slickenside-polished faces on red sandstone boulders blanketing the slopes.  The slickensides are generated by frictional melting of thin films of rock along a fracture separating blocks of stone that have been rubbed together during fault movement.  The polish is scored by parallel grooves formed when heat resistant mineral grains on the face of the rock opposite, scrape across the surface of the melt-film.  Look sharp, once you have spotted one good example, others are not hard to find.  The trail reaches a minor promontory at 3.11 miles that sits below a distinctive arm of rock capped by Coconino Sandstone protruding from the valley slope (Map 1A.3.1).  Here, the trail swings to the right around the arm of rock and into a small, but deeply eroded wash formed along the trace of the main Hermit Fault.

Before forging ahead, it would be instructive to look back up canyon from the promontory in the direction you have come.  This is a good location to observe the entire sequence of sedimentary rocks you have hiked through since leaving the trailhead (Figure 1A.4).  The far side of Hermit Canyon offers a spectacular display of the stair-stepped nature of the rock units exposed in the canyon’s walls (Figure 1A.3.11).  The Paleozoic rocks begin with four Permian layers.  The resistant, capping cliffs of light-colored Kaibab Limestone are followed by a narrow band of darker, tree-covered slopes representing the weaker Toroweap Formation.  This unit is followed by the massive cliffs of the resistant, buff-colored Coconino Sandstone which rest on broad slopes of weak, red Hermit Formation.  The distinctive, red cliffs and slopes below the Hermit comprise the four formations of the Supai Group, all of which can be discerned from here.  The thick cliff-band immediately below the Hermit is the resistant Esplanade Sandstone, the basal Permian unit, which you recently passed through; below it lie three layers accumulated in the Pennsylvanian.  The ledgy slopes correlating to your current position form the alternating mudstones and sandstones of the Wescogame Formation; while the broad band of resistant, sandstone cliffs below the Wescogame mark the position of the Manakacha Formation.  The Supai Group strata finishes off with the slope-forming mudrocks of the Watahomigi Formation; and finally, the shadowy defile cut by Hermit Creek below the Watahomigi brings the top of the Mississippian age Redwall Limestone into view, an impressive, resistant, cliff-forming layer recognized throughout the Grand Canyon.

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Figure 1A.3.11.  The alternating cliffs and slopes formed by differential erosion of the Paleozoic sedimentary rock sequence are on grand display in upper Hermit Canyon; here, one can easily distinguish each formation from the Redwall Limestone at the canyon bottom to the Kaibab Limestone at the rim.

Meanwhile, let’s return our focus to the Hermit Trail.  After navigating through the fault-controlled wash immediately ahead, the trail passes two minor points in rapid succession, reaching the second one at 3.39 miles (Map 1A.3.1).   Although not easily determined, the trail passes from the Wescogame Formation onto the Manakacha Formation between these two minor points.  From the second point, you can view the trail as it traverses the head of a significant amphitheater and out onto a promontory capped by a thick sandstone bed within the Manakacha Formation (Figure 1A.3.12).  Examine the promontory carefully before proceeding; note that as you trace its prominent, capping sandstone layer toward the left, it appears to be displaced upward where the promontory joins the main canyon slope.  In fact, there appears to be a saddle or sag of sorts in the sandstone layer near this position.  This is not an illusion; instead, this is evidence of offset and fracturing of the sandstone (and other layers) produced by down-to-the-left (west) displacement on the Hermit Fault.  When you reach the promontory itself, be sure to look back across the amphitheater to the deeply scoured wash you recently crossed; they are in near perfect alignment and expose the trace of the fault.

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Figure 1A.3.12.  Down-to-the-left (west) displacement on the Hermit Fault is readily observed on a prominent sandstone bench along the Hermit Trail.

Continue forward, making your way through the amphitheater ahead with care.  Several small landslides have recently brought bouldery debris down onto the trail and it is difficult to navigate in places.  Once beyond the last of the four small washes making up the amphitheater, the trail descends to the sandstone-capped promontory discussed earlier.  After a left-hand switchback, the trail drops on to the saddle at the back end of the promontory at 3.83 miles (Map 1A.3.1); here, the Hermit fault lies directly beneath your feet.  The promontory itself offers a pleasant rest and/or lunch stop with awesome views up and down Hermit Canyon.  Take a load off and stay awhile.

When you resume your march, the trail descends from the left-hand (northeast) side of the promontory (as you face away from the canyon) through a fault-induced breakdown slope in the thick sandstone cliff-band, rapidly zig-zagging down a series of tight switchbacks on the first major drop on your Supai traverse.  Incidentally, the sandstone layer forms the base of the Manakacha Formation, so once below that, you enter the final Supai Group unit, the Watahomigi Formation.  This slope-forming unit is dominantly mudstones interbedded with minor sandstone layers and probably reflects the prevalence of shoreline environments in its deposition.  Past the ninth switchback, the Hermit Trail levels out again before rounding a protruding ridge of red mudrocks that terminates in Lookout Point.  From here, the trail shifts to a more easterly course and another lengthy undulating traverse, this time within the Watahomigi Formation, on its way toward Breezy Point.  For the next four-tenths of a mile, the trail remains more or less fixed in elevation as it passes through a large amphitheater cut into the overlying layers of the Supai Group.  The deepest part of the amphitheater contains the debris of another recent landslide, once again necessitating a careful negotiation of the trail.

After gradually rounding another blunted promontory, the trail reaches the western edge of a very large, compound amphitheater (formed on two smaller ones) sculpted from Supai and Redwall Limestone cliffs at roughly 4.55 miles (Map 1A.3.1).  Take a short rest break here, and look to the rock headwall encircling the far side of the amphitheater ahead; red Supai Group layers rest on light-gray Redwall Limestone (Figure 1A.3.13).  Close observation makes it readily apparent that something weird is going on at the end of cliffs overshadowing Breezy Point.  The Supai Group rocks are distinctly offset by down-to-the-west (left) movement on a fault.  In fact, there is a wedge of red Supai rocks driven like a spike down into the surrounding gray-colored layers of the Redwall Limestone; movement on the fault has opened a small graben here and the wedge of Supai rocks has fallen into it.  Look carefully at the Redwall layers to the west (left) of this graben, and you should make out a general tilting of its layers downward, into Hermit Canyon.  The rocks of Breezy Point and the end of the ridge above it are shattered and offset, bisected by two splays of the Hermit fault, the main fault lying further to your left.

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Figure 1A.3.13.  Two spectacularly exposed faults, minor splays of the Hermit Fault, pierce the cliffs near Breezy Point, producing a small graben filled by a wedge of down-dropped Supai Group rocks, westward tilting of the Redwall Limestone, and overall down-to-the-west displacement of the rock layers.

From your promontory position, the trail begins a gradual descent along the back side of the compound amphitheater to the top of the Redwall Limestone and Breezy Point.  In about three-tenths of a mile, the trail passes through the first of the two conjoined amphitheaters, dropping low enough to reach the Watahomigi – Redwall contact; from there, it rises back into Supai rocks and falls back to the contact as it navigates past several small washes within the second amphitheater.  The Supai graben and tilted Redwall layers observed earlier become larger by the minute. As the trail curves to the west and approaches Breezy Point, you must down-climb through more mass-wasting debris on a steep section of trail; be careful treading the loose rubble of this exposed slope.  Here you pass from gray limestone to red mudstone as you cross the southeastern of the two faults that bound the graben containing the Supai Group wedge; notice the highly fractured Supai rocks in this area.  Shortly, the trail reaches Breezy Point at 5.27 miles (Map 1A.3.1) and swings back to the northeast.  Just before the bend, an eroded alignment in the Redwall Limestone just left of the trail gives away the location of the second fault bounding the northwest edge of the small, Supai-filled graben.  The trail ahead lies essentially along the trace of this fault, and as you continue northeast, notice that the rock to your right is red mudstones of the Watahomigi and the rock to your left is Redwall Limestone.  Between here and the next craggy point, the trail becomes deceptively gentle; take a deep breath, the Cathedral Stairs are just ahead.

The juxtaposition between the Supai and Redwall is well-exposed on your final approach to the promontory above the Cathedral Stairs (Figure 1A.3.14); the Supai rocks lay down and to the right (southeast) of the Redwall Limestone outcrops which make up the very end of the point.  Continue past the promontory, and just ahead at 5.64 miles, the Hermit Trail reaches the top of the Cathedral Stairs; your Supai traverse is finally over (Map 1A.3.1).  The Cathedral Stairs are actually a tight series of switchbacks, dropping at breakneck speed through jagged ramparts of the Redwall Limestone along a breakdown slope formed by intense fracturing of the limestone related to fault movement (Figure 1A.3.15).  The faults are the same dual-fault system that you have been traversing since crossing the Supai graben prior to reaching Breezy Point.  Fault-related breakdown slopes such as this one are quite common on rim-to-river trails in the Grand Canyon, and are often the only locations where a path through the massive cliffs of the Redwall can be found.

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Figure 1A.3.14.  A promontory on the Hermit Trail just above the Cathedral Stairs prominently displays the faulted contact between gray Redwall Limestone and red Supai Group rocks; the fault is the northwestern of two parallel faults that bound a small graben filled by a down-dropped wedge of the Supai (former student in orange shirt for scale).

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Figure 1A.3.15.  A fault-shattered breakdown slope provides a toehold for the Cathedral Stairs, forming the only avenue of descent in Hermit Canyon through the resistant, cliff-forming Redwall Limestone.

The day is only getting warmer, and the heat and sunshine become quite intense once past the Redwall, so give a pause as you reach the first switchback and gaze along the trail ahead, but don’t delay to long.  Your initial descent lies within the Supai graben, so the first several switchbacks remain in red mudrocks of the Watahomigi Formation as Redwall blocks rise to either side of your breakdown slope.  As you descend the stairs, the long, narrow arm of Redwall limestone extending out to Copeland Butte lies to your right.  The southeastern of the two faults you have followed for some time bisects this rib of limestone, and fault-induced fracturing, combined with erosion, has generated several cathedral-like spires along the ridge; a view that may have inspired the builders of the Hermit Trail to name this section the Cathedral Stairs.  Notice that the “stairs” here often retain the original cobblestone paving of the Santa Fe Railway-built trail.  Look for the end of the pavement, and the large initials “AB” chiseled into a block of limestone at chest height on the right side of the trail.  This location marks an excellent fossil locality in the 335 million-year-old Redwall Limestone.  Two well-preserved specimens occur on the same side of the trail as the initialed block, a two inch long brachiopod fossil just a few feet up the trail, and a crinoid stem in cross-section about five feet down the trail the size of a nickel.  Rounding the next switchback, a very nice bryozoan fossil, baseball-sized in cross-section, lies on the left side of the trail.  Four more switchbacks bring you to short, flat section of trail where it passes into a narrow gully.  At the next right-hand switchback, look along the outside of the curve along a ledge at about waist height; beautiful crinoid and bryozoan fossils are abundant here.  Crinoids occur in cross-sectional and longitudinal (stem-length) profiles, while the bryozoans appear as frilly patches resembling fine netting.

After navigating your way through a multitude of switchbacks descending an ever-narrowing gully, the Hermit Trail reaches a shady, tree-filled wash draining from a narrow defile that marks the position of the southeastern of the two graben-bounding faults.  From here, the trail heads northeast onto the open slopes below the Redwall cliffs and into the sunshine.  You may wish to take a few moments to rest in the cool confines of the wash, you won’t see the shade again on this day’s trek.  A look back up the trail at the fault-shattered Redwall Limestone offers some perspective on what you’re line of descent (Figure 1A.3.16).  Compare this breakdown slope through the Redwall to that of unfaulted Redwall anywhere in the Grand Canyon, and you gain a bit of insight as why you made that three-mile Supai traverse; the Redwall cliffs are simply impassable anywhere else.  Two additional switchbacks later brings you to about the 6.05 mile mark (Map 1A.3.1) and the approximate location of the Redwall Limestone – Temple Butte Formation contact.  Bouldery slope wash conceals the contact, but if you look to the cliffs 40 feet above your position, you may be able to discern a purplish-brown zone near the break in slope, these are the mudrocks of the 362 million-year-old Temple Butte.  Deposition of the Temple Butte Formation was generally confined to paleovalleys carved into the Muav Limestone that originally drained westward to the ancestral Pacific Ocean.  A rise is sea level invaded these valleys and deposited the distinctive purplish-brown estuarine and fluvial sandstones and mudrocks we see today.

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Figure 1A.3.16. The upper part of the Cathedral Stairs, with its backdrop of faulted Redwall Limestone.

Now begins a long north-trending descent along rubble-strewn slopes through the Muav Limestone (Figure 1A.3.17).  The view from here is quite spectacular, revealing the lower end of Hermit Canyon and the inner gorge of the Colorado River notched into the Tapeats Sandstone and Vishnu basement rocks, as well as large portions of the Tonto Platform toward which you are quickly descending.  The Tonto Platform is named for the Tonto Group (Figure 1.4), the lowermost sequence of Paleozoic sedimentary rocks in the Grand Canyon.  The bench-like feature occurs in the weak Bright Angel Shale, the middle unit of the threesome; the Muav Limestone forms the steeper slopes above, and the Tapeats Sandstone forms the brown cliffs resting directly on crystalline basement.  Rapid erosion of the shales undercuts more resistant cliff-forming units above, allowing the gently undulating bench to expand more quickly than the inner canyon.  The Tonto Group was deposited in the Middle Cambrian during a prolonged marine transgression onto the passive western margin of the North American craton.  Each formation was deposited successively during an overall rise in sea level; first sandy to pebbly Tapeats beaches were laid down in wave-agitated water, then deeper, quieter offshore conditions allowed accumulation of Bright Angel muds, and finally, the limestones of the Muav were formed on a distal, warm-water marine shelf.  Be on the lookout for infrequent trailside exposures of the Muav poking from the debris; the outcrops reveal typically thin, wavy beds of olive-gray, muddy limestone perforated by tubular worm burrows.  Be aware of your tread, the trail from here to into junction with the Tonto Trail is littered with cobbles that I “affectionately” refer to as ankle biters, they just love to roll from beneath your feet and have been known to cause many a sprained ankle.  The northerly traverse ends in just over three-tenths of a mile at a sharp, left-hand switchback that carries you away from ledgy cliffs of purer, more indurated Muav Limestone ahead.  After a brief southerly transit, the trail rapidly down climbs through seven tight switchbacks past the last of the Muav cliff-bands, and returns to a north-trending route.  When the trail reaches the next left-handed switchback at 6.61 miles (Map 1A.3.1), look to the cliffs on your right; the green-gray slopes below yellow-green cliffs indicate that your descent has passed into the Bright Angel Shale (although the Muav – Bright Angel contact is buried in slope wash near the trail).

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Figure 1A.3.17.  The Tonto Platform and inner gorge of the Colorado River observed from the base of the Cathedral Stairs on the Hermit Trail.

The trail’s gradient moderates as it eases onto the Tonto Platform, but the rubble-strewn nature of the trail still requires your full attention.  The Hermit Trail reaches its well-marked junction with the Tonto Trail at 6.86 miles (Map 1A.3.1).  The original Hermit Trail continued southwestward (left) toward Hermit Creek (and its campsite) for just over a mile; this section of trail is now part of the west-bound Tonto Trail.  If your camping destination lies at Hermit Creek, head left.  On the other hand, if your ultimate goal lies at either the Monument Creek or Granite Rapids campsite, then you want to turn northeast (right) at this junction; your destination lies a bit further along the trail (and by now it has probably gotten pretty toasty, so be on your way).  These worthy destinations are described under my hiking trail options entitled “Tonto Trail (Hermit Trail Junction to Boucher Trail Junction – Tr1A.5c)”; “Tonto Trail (Indian Garden to Hermit Trail Junction – Tr1A.5b)”.

Hiking Trail Maps

Map 1A.3.1.  Shaded-relief map of the northwest quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

South Kaibab Trail (Tr1A.4)

The South Kaibab Trail is quite unique among the rim-to-river trails in Grand Canyon National Park.  People, like streams, usually seek the “path of least resistance”, and in the Grand Canyon, this adage holds true; tributary streams to the Colorado River have often carved their canyons along fault zones, where the rocks have been shattered and rendered weak to the forces of weathering and erosion.  These avenues of descent to the river naturally cut their way through even the most resistant of rock layers, strata such as the Coconino Sandstone and Redwall Limestone, and for as long as humans have visited or lived in the canyon exploiting its resources, they have known of these pathways.  Human engineered trails in the park invariably follow similar, previously established routes, making their way downward through “breakdown slopes” notched into resistant rocks along fault-controlled weaknesses.  However, this is not true of the South Kaibab, for much of its length, the trail clings to a dramatic ridgeline descent, offering to hikers a smorgasbord of sweeping, panoramic views unparalleled by any other trail at the Grand Canyon.  The South Kaibab Trail is historically different as well.  Most rim-to-river trails were established long ago by Native American peoples and simply “remodeled” in the late 1800s by settlers of European descent seeking riches within the canyon, real or imagined.  But the South Kaibab is a modern route, constructed at the time (in the mid-1920s) by the National Park Service as a public means by which park visitors could bypass Ralph Cameron’s privately owned and tolled Bright Angel Trail.  Fortunately for the park visitor’s of today, Cameron’s legal battles with the government and other private entities to maintain his personal business rights contributed to the building of this wonderful trail.

The trail’s awe-inspiring vistas do come with a price, however; it is one of the shortest and steepest trails into the canyon, shade is at a premium, and unlike its “Corridor Trail” companion, the nearby Bright Angel Trail, there is no water for its entire length.  After a misleadingly gentle start, the South Kaibab literally plunges into the canyon.  The Park Service indicates that “during winter months, the sun exposure is likely to keep most of the trail relatively free of ice and snow”; but since most hikers ply this path during summer months, the constant sunshine is really more of a problem than a boon.  All of this exposure can quickly become your worst enemy, frying your skin and bringing on dehydration and heat exhaustion.  With your safety in mind, I highly recommend beginning a hike on this trail in the cool hours of the early morning; the marvelous sunrise views are worth it!  If a day-hiking outing is your intention, I recommend Skeleton Point as a turn-around destination; at roughly six miles round-trip, it offers the best inner canyon views and avoids the ascent back up through the Redwall that you would by necessity have to make if you continue any further.

This rim-to-river descent has some of the most interesting and easily accessed geology in the park, making it an excellent learning opportunity too.  The upper five miles of this seven and one-half mile trek take you step by step, backward through the sedimentary rocks accumulated during the Paleozoic Era, and offers many occasions for close-up examination of sedimentary facies and “big-picture” stratigraphic relationships.  The last two and one-half miles affords a rare, personalized glimpse of Late Proterozoic sedimentary rocks within the Grand Canyon Supergroup, as well as some of the canyon’s multitude of structural features too.  The trail begins with a short series of tight switchbacks through the Kaibab Limestone. This is where ice will most likely be encountered during the winter months. After these initial switchbacks, the trail traverses along the slope formed by mudrocks of the Toroweap Formation to Ooh Ah Point and the first panoramic view of the canyon.  A real geological treat of the South Kaibab are the exceptional opportunities for observing Paleozoic strata, and Ooh Ah Point is no exception.  The promontory lies below Yaki Point, near the top of the buff-colored Coconino Sandstone, and directly above Cedar Ridge.  Stretching its long arm toward Grand Canyon’s inner gorge below, the ridge, having shed much of its colluvial debris, nicely exposes most the remaining Paleozoic formations.

From Ooh Ah Point, the South Kaibab Trail descends several steeply-plunging switchbacks and passes onto the shadeless crest of Cedar Ridge.  Hikers will notice an abrupt change to the red mudstones of the Hermit Formation where the trail’s gradient decreases dramatically.  At the base of the Hermit slope, the Cedar Ridge Rest Area has composting toilets, but no water or emergency phone.  After leaving the rest area, the trail winds more gently downward through the alternating sandstones and mudstones of the Supai Group, even a relative novice can distinguish the four rock formations of this stratigraphic group fairly easily.  At first, the trail maintains a ridgeline descent, but then drops gradually around the east face of O’Neill Butte and back onto the ridge once more, until it reaches Skeleton Point and the top of the Redwall Limestone.  Be sure to take the spur trail on the left here for an amazing downcanyon vista of the Tonto Platform and your first good view of Upper Granite Gorge and its stark walls of Vishnu basement; the Park Service recommends that day hikers return to the rim from this location.

The South Kaibab Trail drops directly off the end of Skeleton Point and quickly weaves its way down through a dramatic section of switchbacks blasted directly out of the gray Redwall Limestone cliffs.  At the base of the cliff, hikers will encounter the ledgy outcrops of the olive-drab Muav Limestone, and as the trail begins to straighten out and its steep tread gradually lessens, the greenish-gray slopes of the Bright Angel Shale become readily distinguishable. The trail reaches the Tipoff Rest Area at about five miles from the rim on the relatively flat surface of the Tonto Platform.  This topographic bench has formed where remnants of the weak and easily eroded Bright Angel Shale rest on the resistant Tapeats Sandstone, lowermost of the Paleozoic rock units.  More pit toilets and an emergency phone can be found at the Tipoff, but no water.  For hikers wishing to utilize the Tonto Trail to the east or west, the intersection is located just downslope of the pit toilets, near the metal hitching posts.  Day-hikers, if you have made it this far, don’t turn around quite yet, the splendor of the inner gorge literally “lies just around the corner” and walking to its first overlook will only add a few tenths of a mile extra to your return to the rim (now a significant nine-mile round-trip undertaking anyway).

Below the Tipoff, the South Kaibab Trail loosely follows the course of the older Cable Trail, built in 1907 to provide visitor access to an early cable car system across the river that was in use prior to construction of the present-day suspension bridge.  Vestiges of this earlier trail can be seen as the South Kaibab Trail descends toward the Colorado River; access to Bright Angel Campground is now provided by the Black Bridge (built in 1921).  The real “jewel” of the South Kaibab begins after it descends through the Tapeats Sandstone just past the Tipoff.  On many of the Grand Canyon’s rim-to-river trails, hikers would pass the Great Unconformity and normally encounter the dark, foliated schists and metamorphosed granites of the Vishnu basement next; but not here.  Instead, the trail traverses three sedimentary rock formations rarely encountered in the canyon, the Shinomo Sandstone, Hakatai Shale, and Bass Limestone of the lower Grand Canyon Supergroup.  These units form the basal portion of the Unkar Group, deposited along the shores of an inland seaway on the Rodinian supercontinent between 1250 and 1100 million years ago.  Preservation of these units in this area is linked to the nearby Bright Angel and Cremation Faults.  Late Proterozoic extensional movement on these faults during breakup of Rodinia around 750 million years ago fractured Supergroup rocks accumulated earlier by normal faulting, and generated a small graben here (the Cremation Graben, a block of the earth’s crust dropped downward between bounding normal faults).  Adjacent crustal blocks were uplifted, and the entire region was beveled flat by erosion between 750 and 545 million years ago to produce the Great Unconformity (on which the Paleozoic sequence was later deposited), but the lower Unkar Group rocks within the Cremation Graben were protected from this erosion and so breathtakingly remain for our geological enjoyment today.

Faulting and graben formation witnessed along the South Kaibab Trail speak fundamentally to the significance of plate tectonics in shaping the North American craton, and indeed, all of the earth’s continental masses.  The supercontinent of Rodinia was assembled during deposition of the Grand Canyon Supergroup’s Unkar Group, Nankoweap Formation, and lower Chuar Group, but by roughly 800 million years ago, as the upper Chuar Group and Sixtymile Formation accumulated, breakup of Rodinia had already commenced.  When faults such as the Bright Angel and Cremation fractured the proto-North American continent in the Neoproterozoic, the Grand Canyon region lay to the east of the main rift zone tearing apart Rodinia.  As the large plate fragments of Antarctica and Australia rifted away from Rodinia to form an intervening ocean basin, the new passive margin of western North America was left as a ragged line running from Montana southward to Southern Nevada.  The continental crust in the Grand Canyon region was subjected to east-west stretching that produced extensive NW-SE oriented normal faults that were often paired with grabens large and small, expressed by the complex structural relationships viewed first hand along the South Kaibab Trail.  The structural depressions formed by grabens allowed preservation of wedge-shaped bodies of the Grand Canyon Supergroup when intervening highlands were subsequently removed by extensive erosion and then buried by renewed deposition on the west coast’s passive continental margin in the Paleozoic.

The South Kaibab trailhead is located near Yaki Point, the South Rim promontory overlooking Pipe Creek Canyon to the west and Cremation Canyon to the east.  The Park Service does not permit parking at the trailhead because of the popularity of this scenic area and its extremely limited space.  Hikers must use the park’s free shuttle bus system to reach the trailhead; your most likely strategy would be to catch a shuttle on the Blue Route from the Backcountry Information Center (the most secure long-term parking area in the park) to Canyon View Information Plaza at the Visitor Center, and then transfer to a shuttle on the Orange Route.  The South Kaibab trailhead is the first stop on the Orange Line (Stop #1 on Map 1A.1 and Map 1A.4.1).  If you plan to camp below the rim, the park service warns that “at-large camping is not permitted on Corridor Trails; visitors must camp in designated campgrounds”.  The only such camping option along the South Kaibab Trail is at Bright Angel Campground, at trails end, near the confluence of Bright Angel Creek and the Colorado River in lower Bright Angel Canyon.  The hike down the South Kaibab Trail to the campground is about seven and one-half miles long and will likely take 4-6 hours (depending on how many scenic vistas you explore).  Most hikers planning an overnight stay at Bright Angel Campground prefer to hike down the South Kaibab Trail and up the Bright Angel Trail. Although both trails have nearly identical elevation changes, the South Kaibab Trail is more consistently sloped, making it shorter but steeper, and lacks the water or shade available on the Bright Angel.

And so your hike begins.  Initially, the South Kaibab Trail maintains a course along the eastern wall of upper Pipe Creek Canyon (Map 1A.4.1).  At first, the trail descends through the Kaibab Limestone in a steep series of tight switchbacks.  The hike here often begins in the deep shade of early morning, so features may be difficult to pick out, but close observation of the rocks at trailside should reveal many light-colored chert nodules scattered throughout the ubiquitous grayish limestone beds.  Some 260 million years ago, sponges thrived on the floor of a warm shallow sea, and it is their siliceous framework of spicules that form the chert nodules you see today.  Other creatures also occupied the warm marine environment, such as the fossilized brachiopods found near the fifth switchback.  The trail soon exits the last switchback in the Kaibab, and at about 0.35 miles (Map 1A.4.1), it reaches the contact between the Kaibab Limestone and Toroweap Formation.  The contact lies in slope here, but if you look toward the head of the canyon and even with your position, it is relatively easy to see where limestone cliffs abruptly change to mudrock slope at the contact.  As you hike and enjoy the scenery, be sure to take the time to look all around, especially up and across the canyon (Figure 1A.4.1); the processes of differential erosion have created distinctly contrasting cliff-slope-cliff exposures in the Kaibab Limestone, Toroweap Formation, and Coconino Sandstone, the three upper Paleozoic rock units which are so beautifully on display in this area.  From here, the trail begins a long, gradually descending traverse through the vegetated, but debris-covered slopes of the Toroweap Formation.  The Toroweap consists of alternating layers of mudstone, muddy limestone, and gypsum-rich, muddy evaporite deposits, rocks that are all relatively prone to weathering and erosion and typically form slopes like this one.  In this relatively cool, moist environment, the clay-rich soils of the Toroweap slope are prone to creep, a slow mass wasting process by which particles are heaved from the slope during nightly freezing, only to fall back to the slope at a lower position during daily thaws.  Although you rarely see the process in action, evidence that creep is common on this slope surrounds you in the form of loose blocks of Kaibab Limestone, back-tilted into the slope, having ridden along on the creeping soil.

Figure 1A.4.1 Alternate cliff-slope-cliff bands of Kaibab, Toroweap, and Coconino formed by differential erosion copyrighted

Figure 1A.4.1.  The processes of differential erosion have created distinctly contrasting cliff-slope-cliff exposures in the Kaibab Limestone, Toroweap Formation, and Coconino Sandstone in upper Pipe Creek Canyon.

The Toroweap Formation was deposited about 265 million years ago (Figure 1.4) on an arid, passive marginal, shallow marine shelf subject to a fluctuating shoreline position.  Its limestones and mudstones accumulated under deep to shallow water conditions caused by minor changes in sea level; and its interbedded evaporites formed during periodic drying on extensive mud flats, probably related to repeated low tides.  In 0.91 miles (Map 1A.4.1), shortly before you reach the ridgeline descending from Yaki Point, your tread encounters the transition between the Toroweap Formation and the underlying Coconino Sandstone (Figure 1A.4.2).  Careful observation indicates the gradual, intercalated contact between the crossbedded, buff-colored sandstones of the Coconino below to the planer interbeds of brownish mudstones, limestones, and evaporites in the Toroweap above.  As you descend through the 270-million-year old Coconino Sandstone (Figure 1.4), be sure to examine its unique mega-scale crossbedding, the layers of sand dipping fairly uniformly at about 30º are a product of windblown sand accumulating on the downwind side of the migrating sand dunes.  More or less flat-lying truncation features exhibited between packages of crossbedding are bounding surfaces produced by wind deflation of previously deposited dune sand.  These dunes were deposited in a giant sand sea called a desert erg that had formed on western North America’s passive continental margin during marine retreat and subaerial exposure.

Figure 1A.4.2 The Toroweap-Coconino contact on the South Kaibab Trail copyrighted

Figure 1A.4.2.  The gradual, intercalated contact between the crossbedded, buff-colored sandstones of the Coconino below to the planer beds of brown mudstone in the Toroweap above as observed along the South Kaibab Trail.

Your gradual descent on the South Kaibab Trail comes to a temporary halt shortly beyond the Toroweap-Coconino contact at a prominent left-hand, ridge-hugging switchback known as Ooh Aah Point (Map 1A.4.1).  Appropriately named, this overlook occupies the ridge crest coming down from Yaki Point (above and behind you to the southeast), where the trail is no longer boxed in by the confining walls of Pipe Creek Canyon.  Perched on boulders of Coconino Sandstone, the vista provides your first awe-inspiring views of the main Grand Canyon (Figure 1A.4.3), and serves as a great vantage point from which to observe Cedar Ridge, the bedrock divide separating Pipe Creek Canyon on the west from Cremation Canyon to the east.  The ridge is held up by a foundation of Redwall Limestone, its gray-colored cliff poking out toward the inner gorge at the far end of the rocky divide, and capped by remnants of the Supai Group’s red sandstones and mudrock.  Take a moment to examine the Supai Group rocks in more detail.  O’Neill Butte and the top of the ridgeline are formed by the thick cliff-band of the Esplanade Sandstone (with a thin veneer of Hermit Formation shales above).  The slope former immediately below this distinctive cliff is formed of mudstones in the Wescogame Formation.  Several thin cliff-bands separated by slopes comprise the interbedded sandstones and mudstones of the Manakacha Formation, and at the base of the Supai Group directly overlying the massive Redwall cliff, another thick, slope-forming unit predominantly consisting of mudstones is formed by the Watahomigi Formation.  Accumulated between 310 and 285 million years ago on an arid, low-gradient coastline, the rock layers of the Supai Group represent alternating mud deposition in tidal flats related to temporary sea-level rise, and sand dune accumulation associated with minor sea-level retreat and subaerial exposure.  Geologists believe that sea level fluctuations were triggered by growth and decay of ice sheets over Gondwanaland, a large continental mass centered over the South Pole during the Permian.  As the continental ice sheet grew, water in the world ocean was locked up on land, sea level fell, and the coastal deserts of the proto-North American southwest to expanded.  Waning of the ice sheet dumped water back into the world ocean, sea level rose, and shallow seas inundated the Grand Canyon region with extensive mudflats.

Figure 1A.4.3 Cedar Ridge from Ooh Aah Point on the South Kaibab Trail copyrighted

Figure 1A.4.3. A marvelous view of the Grand Canyon awaits the South Kaibab Trail hiker at Ooh Aah Point; O’Neil Butte caps Cedar Ridge in the foreground , butte and ridge comprised of the reddish, interlayered units of the Supai Group overlying the Redwall Limestone.

From Ooh Aah Point, the South Kaibab Trail assumes a more rapid pace downward through the remainder of the Coconino Sandstone, continuing to offer excellent outcrops of mega-crossbedded sandstone, and at 1.39 miles (Map 1A.4.2), shortly after negotiating a left-hand switchback along the east side of the ridgeline, the trail passes the contact between the Coconino Sandstone and Hermit Formation.  Note the abruptness of the contact denoted by the instantaneous change from light-colored, fine-grained, quartz-rich sands to red muds.  Composed of mudrocks and minor sandstones, the brick-red Hermit is usually a slope-former, and just below, you can easily see the cliff-slope break.  The Hermit Formation was formed about 275 million years ago (Figure 1.4), and is considered by geologists to represent low-energy riverine and deltaic systems associated with a low-gradient, floodplain-dominated, tropical coastline.  Back on another section of gradually descending straightaway, the trail heads northwest and formally onto Cedar Ridge where it quickly finishes off the Hermit Formation.  At 1.58 miles from the rim (Map 1A.4.2), the trail passes Cedar Ridge Resthouse, providing hikers with composting toilets and a few shady juniper trees, but no water.  This a good turn-around point for those not accustomed to canyon hiking or for families with younger children seeking a pleasant little day-hike; but before you go, include a short detour just 50 yards to the left of the toilets at the western edge of the ridgeline.  With little effort, you should find a small, glass-covered stone shelter that holds several nice specimens of fossilized ferns taken from mudrocks in the Supai Group beginning just below.  These fern fossils suggest that although the Permian age climate was dominantly arid in the Grand Canyon region during Supai deposition, coastal conditions must have provided ample moisture in some areas for plant growth.  A quick stroll over to the edge of the ridge after checking out the fern fossils affords a spectacular panoramic view across Pipe Creek Canyon and to more distant points along the South Rim and inner canyon (Figure 1A.4.4).  This view takes in the entire sequence of Paleozoic sedimentary rocks, the distinctive bench of the Tonto Platform, and the crystalline basement rocks exposed within Upper Granite Gorge.  Using the alternating cliff and slope topographic created by differential erosion of the rock units, see if you can distinguish individual rock layers depicted in Figure 1.4.

Figure 1A.4.4 The view downcanyon to the northwest from the Cedar Ridge Resthouse copyrighted

Figure 1A.4.4.  The downcanyon vista that awaits eager hikers as they look northwest and into the Grand Canyon from the Cedar Ridge Resthouse.

Departing the Cedar Ridge Resthouse, the South Kaibab Trail now traverses the eastern side of the ridgeline and past O’Neill Butte, dropping steadily downward through outcrops of the Supai Group formations described earlier (Map 1A.4.2).  The trail descends through a massive cliff-band of Esplanade Sandstone (Figure 1A.4.5) at 1.91 miles first, and then into the mudstone slopes of the Wescogame Formation.  At 2.17 miles, the trail crosses the first of three prominent sandstone cliff-bands separated by slopes of mudstone that mark the position of the Manakacha Formation; then shortly, it angles to the left, offering tantalizing views of Skeleton Point and the Redwall Limestone cliff at the end of Cedar Ridge (Figure 1A.4.6).  A rounded cap of mudstones and thin limestones comprising the Watahomigi Formation lies atop the ridge.  Look to the sunlight eastern face of the ridge; prominently displayed, the South Kaibab Trail snakes its way down the impressive wall of gray Redwall Limestone and passes into the ledgy slopes of the grungy-green Muav Limestone.  Curiously, Figure 1A.4.6 also shows the true nature of the Redwall’s color; it is misleadingly red where muds weathered from the overlying Watahomigi unit have coated it, but gray further out on the ridge where these muds have long ceased to wash over it.

Figure 1A.4.5 The Esplanade Sandstone cliffs on the South Kaibab Trail copyrighted

Figure 1A.4.5.  Passing through the Esplanade Sandstone cliff on the South Kaibab Trail.

Figure 1A.4.6 The end of Cedar Ridge from the northeast flank of O'Neill Butte copyrighted

Figure 1A.4.6.  The end of Cedar Ridge comes prominently into view from the trail on the northeast flank of O’Neill Butte; red mudstones of the Watahomigi Formation cap the nearer ridge crest, but the massive cliff of the Redwall Limestone, underlain by the ledgy slopes of the Muav Limestone are exposed in its eastern face.

After rounding the northwestern tip of O’Neill Butte, the trail regains the ridge crest at 2.64 miles (Map 1A.4.2).   Here, it is worth the short hop just off the trail to the left (west) for a unique “surprise” awarding the patient observer.  Here, an odd pattern of polygonal cracks is weathered into a limestone bed in the lower Watahomigi Formation exposed on the ridge crest, fractures that formed over a cave collapse in the top of the Redwall Limestone, although the cave itself is not visible.  Redwall caves such as this are often filled with mud and rubbly debris that has lithified into a feature known as a breccia pipe.  Elsewhere in the Grand Canyon, these pipes contain mineralized copper and uranium ores brought in by groundwater and are correlated with lithified valley fill that makes up the discontinuous, patchy or trough-like deposits of the Late Mississippian Surprise Canyon Formation  (Figure 1.4) where sinkholes and channels were eroded into the top of the Redwall Limestone.  Miners exploited these ores in the late 1800s and early 1900s (consider the Orphan Mine just west of Grand Canyon Village, and the Last Chance Mine further to the east on Horseshoe Mesa).

Continue on the South Kaibab Trail to Skeleton Point near the end of Cedar Ridge at 3.19 miles (Map 1A.4.2).  The trail steps down into the uppermost layers of the Redwall Limestone just short of a spur trail that diverges to the left taking you to the Skeleton Point overlook (Figure 1A.4.7); enjoy a brief rest here before plunging through the Redwall switchbacks.  Before descending though, it is well worth your time to make a stop at Skeleton Point, the eye-catching scenery viewed from this overlook may well be one of the most geologically interesting locations in the park.  And if this is your turn-around destination for a leg-stretching six-mile round-trip day-hike, please make this your lunch stop; they don’t get any better, even in a place as “grand” as the Grand Canyon.  Once you have settled in at the point, take a good look around and familiarize yourself with a few landmarks (Figure 1A.4.8).  Your panoramic view is bordered by cliffs of Redwall Limestone to the right (southwest) and to the left (northeast).  Below you, a wide topographic bench, sloping gradually away and to the right (northwest), is known as the Tonto Platform.  Immediately to the right of this bench is the deep, narrow defile of Upper Granite Gorge cut by the Colorado River.  On the far right (northeast), just left of the Redwall cliff, a large tributary canyon enters the inner gorge from the northeast; this is Bright Angel Canyon.

Figure 1A.4.7 The top of the Redwall Limestone near Skeleton Point copyrighted

Figure 1A.4.7.  The first outcrop of Redwall Limestone makes a convenient rest stop on the South Kaibab Trail just before it plunges through a series of steep switchbacks cut into the east face of Cedar Ridge.

Now let’s get down to the business of describing the wonderful geology you can see from here.  Sweeping down from your left and in the background are the multihued cliffs and slopes of the Paleozoic sedimentary rock sequence you have been traversing since the beginning of your hike (Figure 1A.4.8).  Nearer your position, on the southeast side of Upper Granite Gorge, the Middle Cambrian Tonto Group is well displayed (Figure 1.4).  Below the Redwall Limestone cliffs, the ledgy yellowish-green slopes of Muav Limestone appear first, followed downslope by the gentler topography of the Bright Angel Shale, its greenish-gray mudrocks spread over most of the Tonto Platform, and finally, the brown, cliff-forming layer of the Tapeats Sandstone lying atop the Great Unconformity and darker Vishnu basement.  This threesome of sedimentary rock formations was deposited in successive, conformable layers, during an overall rise in sea level.  As the west coast of North America was inundated by marine advance, Tapeats beaches and nearshore settings deposited sandy to pebbly material laid down in wave-agitated water, then Bright Angel muds accumulated in deeper, quieter waters offshore, and these were eventually followed by deposition of the Muav’s muddy limestones in the calm, deeper waters of a warm-water marine shelf teaming with biological productivity.  Weathering and erosion has caused rapid backwasting of the weak mudstones of the Bright Angel Shale which undercuts the more resistant cliffs above leaving the wide bench of the Tonto Platform as we now see it.  The Upper Granite Gorge exposes Middle to Late Proterozoic crystalline basement, predominantly the dark, vertically foliated metamorphic rock of the Vishnu Schist in this view.

Figure 1A.4.8 Panoramic vista from Skeleton Point copyrighted

Figure 1A.4.8.  The panoramic view from Skeleton Point; exposed in all their glory, from this location, one can observe the Paleozoic sequence, Vishnu basement, rocks of the Grand Canyon Supergroup, and evidence of ancient crustal deformation.

Looking to the northwest, on the far side of Upper Granite Gorge and Bright Angel Canyon, we see relatively little of the distinctive Tonto Platform; instead, nearer the river, sandwiched between slopes of Bright Angel Shale above and cliffs of Vishnu basement below, northeasterly tilted layers of brick-red to brown sedimentary rocks are exposed (Figure 1A.4.8).  These layers are comprised of the Bass Formation, Hakatai Shale, and Shinomo Sandstone in vertical sequence, the three lowermost units of the Mesoproterozoic Unkar Group, part of the larger, nearly 13,000 foot-thick package of rocks called the Grand Canyon Supergroup.  Bright Angel Canyon has been eroded along the zone of weakness created by fracturing of rocks during repeated movements on the Bright Angel Fault; in the Neoproterozoic, this fault was first activated as a normal fault by crustal extension associated with the breakup of the supercontinent of Rodinia.  Although much of it is eroded away, this fault once formed the back edge of a large slab of crust rotated down and to the northeast as a one-sided graben, now preserved as the northeast-tilted remnants of Supergroup rocks truncated against the fault zone.  The Tapeats Sandstone occurs on the north side of Upper Granite Gorge, both upriver and downriver of the tilted Shinomo Sandstone, but is not present above the Shinomo.  Geologists believe that the Shinomo literally protruded above the waves, forming a resistant island in the rising waters associated with the Middle Cambrian marine transgression, and the Tapeats Sandstone was only deposited around its edges; it took the deeper water deposition of the Bright Angel Shale to bury the island.

Return to the main trail and begin your precipitous downclimb through the Redwall Limestone.  This formation accumulated on a warm, shallow marine shelf during the Mississippian, roughly 335 million years ago (Figure 1.4).  As you descend, take notice of the numerous caves peppering nearby cliffs of the Redwall; many of these were excavated long ago by groundwater cruising through the rock when the Grand Canyon itself had not been dissected any deeper than that level.  If you are lucky, you may time your descent during a Grand Canyon sunrise; they can be quite spectacular from here (Figure 1A.4.9).  The South Kaibab makes its last switchback for some distance, and just ahead at 4.07 miles (Map 1A.4.2), along a straightaway section of trail constructed at a distinct break in slope, you reach the Redwall Limestone-Muav Limestone contact.  Note the solid gray limestones above, and the ledgy, yellowish-green, muddy limestones below (Figure 1A.4.10).  Although not particularly discernible here, this contact marks a major disconformity of some 130 million years between deposition of the Cambrian Muav Limestone, its subaerial exposure and erosion, and deposition of the Mississippian Redwall Limestone.  Purplish-brown lenses of dolostone in the vicinity (best seen looking rimward back at the switchback) mark deposition of the Temple Butte Formation.  The patchy nature of its distribution related to accumulation in tidal channels draining mudflats associated with an arid coastline some 362 million years ago (Figure 1.4).  As you round the end of the great arm of rock extending into the canyon formed by Cedar Ridge, climbing down through the ledgy slopes of the Muav, be sure to look for ripple marks and tubular-shaped bumps interpreted to be trace fossil worm burrows.  These sedimentary structures are good indicators of depositional environment, the Muav having formed in relatively deep, quite waters off shore of the shoaling zone (but not deep enough to be unaffected by occasional wave action).  Eventually, you transition into the mudrock of the Bright Angel Shale, and at 4.52 miles (Map 1A.4.2), the trail makes a sharp right-hand bend as it crosses a gully; here, outcrops of the olive-drab Bright Angel can be observed (Figure 1A.4.11).  From this position, the trail passes several more outcrops of Bright Angel as it’s gradient continues to lessen.  A quick jaunt brings you to the Tipoff at 4.91 miles (Map 1A.4.2), where the South Kaibab Trail encounters the east-west Tonto Trail and lies on the verge of the inner gorge.  Near the trail junction, you’ll also find composting toilets to the right and an emergency phone just down the trail ahead of you.  There is no water available at this location.

Figure 1A.4.9 A spectacular sunrise on the South Kaibab Trail copyrighted

Figure 1A.4.9.  A sunrise on the South Kaibab Trail viewed from the switchbacks cut into the Redwall below Skeleton Point.

Figure 1A.4.10 The Redwall Limestone-Muav Limestone contact copyrighted

Figure 1A.4.10.  The Redwall Limestone-Muav Limestone contact on the South Kaibab Trail, indicated here by the break in slope associated with the abrupt change from the dense, resistant, massive limestone of the Redwall to weaker, less resistant, muddy limestone of the Muav.

Figure 1A.4.11 The Muav Limestone-Bright Angel Shale contact copyrighted

Figure 1A.4.11.  The Muav Limestone-Bright Angel Shale contact exposed in a gully at mile 4.52 along the South Kaibab Trail.

Until now, your downward trek has been a relatively straight forward geologic affair, sweeping backward in time through sedimentary rocks representative of Colorado Plateau stratigraphy and regional deposition on the southwestern passive margin of the North American continent during the Paleozoic Era, and not unlike all of the other rim-to-river trails on the South Rim; however, that familiar status is about to change.  Once past the Tipoff, the South Kaibab enters a narrow valley etched into layers of brown Tapeats Sandstone, the lowermost unit of the Paleozoic sequence.  Examine the blocks of sandstone that line the trail here, the bedding planes are covered in well preserved worm burrows.  Layers of thick sandstone alternate with thin mudstone that have weathered back into the growing height of the valley’s walls giving them a variegated appearance.  Some sandstones exhibit nice examples of herringbone crossbedding in outcrop; these features suggest sandy deposition on a wave-agitated shoreline.  At 5.12 miles (Map 1A.4.2), the trail swings sharply to the right at a promontory overlooking the inner gorge and leaps backward in time by 550 million years.  Above your position is the brown, layered sandstone cliff of the Cambrian Tapeats Sandstone, but at your feet are the dense, purplish sandstones of the Shinomo Sandstone.  This erosion surface and the enormous gap in the rock record it represents forms the multifaceted Great Unconformity, here occurring as an angular unconformity because the Shinomo Sandstone, a formation within the Unkar Group of the Grand Canyon Supergroup, is deformed, tilted downward in a southeasterly direction, but overlain by the undeformed Tapeats Sandstone.  The Shinomo’s deformation is not obvious in outcrop here, but the South Kaibab Trail has crossed into the Cremation Graben, a crustal block dropped downward by extension associated with the Cremation and Bright Angel normal faults.  Just ahead, the trail enters the top of a small amphitheater notched from the lip of the inner gorge.  Scan the trail ahead as it circles around and downward through the back of the amphitheater to a small, but prominent ridge a few hundred yards distant.  The ridge is mainly comprised of the stratigraphically lower Hakatai Shale, but its northern end is capped by a remnant of flat-lying Tapeats Sandstone.  Look closely at the brick-red layers of Hakatai Shale exposed in the near side of the ridge below the Tapeats outcrop; they clearly tilt downward to the right (southeast) away from the river (Figure 1A.4.12).  This awesome display of tilted sedimentary rocks beneath undeformed sedimentary rocks is the same angular unconformity you just crossed at trailside.  The significance of this feature is that the Hakatai Shale and its other Supergroup partners must have been deformed and tilted prior to deposition of the Tapeats Sandstone; this deformation accompanied uplift and erosion to form the beveled surface of the Great Unconformity on which the Tapeats was later accumulated during the Cambrian “Tonto Group” marine transgression.  The tectonic event responsible for the observed tilting of the Supergroup rocks was crustal extension and normal fault movement caused by the breakup of the Rodinian supercontinent in the Neoprotrozoic.

Figure 1A.4.12 Angular Unconformity between Tapeats Sandstone and Hakatai Shale copyrighted

Figure 1A.4.12. The Angular Unconformity between the Tapeats Sandstone and the Hakatai Shale within the Cremation Graben.

The Cremation Graben preserves a narrow sliver of lower Supergroup rocks.  From your perch on the lip of the amphitheater, carefully examine the rocks exposed in the walls of Upper Granite Gorge on both sides of the river, up and down stream, to reveal the boundaries of the Cremation Graben.  First, look down river at the cliffs below the promontory that encloses the far side of the small tributary drainage immediately to your west.  A brown cliff of Tapeats Sandstone lies directly on dark, vertically foliated Vishnu Schist; there are no tilted Supergroup rocks present.  This juxtaposition of rock units indicates that they occupy a location outside of the graben, on the upthrown side of the graben’s western bounding normal fault, the Tipoff Fault, a splay of the Cremation Fault.  Any Supergroup rocks once present were stripped off by the erosion that produced the Great Unconformity (here a nonconformity between the Tapeats and Vishnu).  Now look upriver on the opposite side of the inner gorge, once again you see Tapeats Sandstone lying on Vishnu Schist indicating that this location also lies on the upthrown side of the graben, in this case on the upthrown, eastern side of the Cremation Fault.

Pressing forward, the trail climbs down through the Shinomo Sandstone and angles around the back side of the amphitheater as previously described.  At first, a growing wall of Shinomo (capped by a thin veneer of Tapeats Sandstone) rises above you, but the cliff abruptly ends in about one-tenth of a mile at a rubble-strewn, mudrock slope of Hakatai Shale.  Layers within the Hakatai terminate against the Shinomo, indicating the presence of a fault. This is a small normal fault internal to the larger graben discussed earlier, one of two actually (you’ll encounter the second one soon).  The fault has dropped younger Shinomo downward against older Hakatai.  Soon, the South Kaibab Trail reaches a saddle in the ridge on the far side of the amphitheater at 5.38 miles (Map 1A.4.2).  Hakatai Shale is exposed within the saddle, but Tapeats Sandstone caps the end of the ridge as previously indicated (Figure 1A.4.13a).  Large boulders have broken off this isolated block of Tapeats Sandstone and are scattered around its margins.  Walk over to examine several of these boulders, the one teetering on a pedestal of Hakatai is the most enlightening; some boulders such as this one contain distinctive layers of breccia comprised of angular chunks of purplish Shinomo Sandstone encased within brown Tapeats sand grains (Figure 1A.4.13b).  These fragments of Shinomo provide evidence of ancient rock falls hammered from sea cliffs by wave action and incorporated into the beach sands that would later be lithified into the Tapeats Sandstone as sea level rose around an island of resistant Shinomo Sandstone during the Cambrian marine transgression 545 million years ago.

Figure 1A.4.13a & b Saddle in the Hakatai ridge within the Cremation Graben copyrighted

Figure 1A.4.13.  A narrow ridge of Hakatai Shale capped by an outlier of Tapeats Sandstone internal to the Cremation Graben (A); the Tapeats Sandstone contains fragments of Shinomo Sandstone (B), indicating that the present-day nearby cliffs of Shinomo once stood at the edge of a wave-lashed sea cliff during the Cambrian marine transgression, dumping the occasional rockfall onto the sandy beaches along its base.

Back on the trail; hike toward the overlook at the end of the ridge at mile 5.56 (Map 1A.4.2).  Passing a few more Tapeats boulders on the way, look back toward the head of the amphitheater you just traversed (Figure 1A.4.14).  The normal fault internal to the Cremation Fault that you crossed a few moments ago back at the head of the amphitheater is plainly expressed by the offset between the Shinomo Sandstone and Hakatai Shale.  Down-to-the-west displacement of the Shinomo against the Hakatai is evident, and the Hakatai layers east of the fault can be traced east across the amphitheater to the very ridge you stand on.  Look past the saddle you just left, east of your position stands another wall of Shinomo Sandstone, this time juxtaposed downward on the east against Hakatai Shale, the Hakatai to the west of the Shinomo cliff can again be traced west to your ridge.  These relationships indicate that the block of Hakatai Shale between these two normal faults was uplifted and corresponding Hakatai outcrops lay at lower positions to either side, below the Shinomo cliffs on the downdropped sides of the faults.  Figure 1A.4.15 models crustal extension here related to the Bright Angel and Cremation Faults which generated the Cremation Graben; the small, complex graben bounded by normal faults and internally consisting of two, even smaller grabens separated by a ridge.  After contemplating these geologic complexities, enjoy the scenery at the overlook, the inner gorge views are stupendous!

Figure 1A.4.14 Normal fault internal to the Cremation Graben offseting Shinomo against Hakatai copyrighted

Figure 1A.4.14.  The Shinomo Sandstone displaced by down-to-the-west motion along the western of two normal faults bounding a small graben internal to the larger Cremation Graben.

Rounding the ridge, your route quickly dives downward, sweeping around the back edge of a second amphitheater formed in the heart of the eastern of the two small grabens internal to the Cremation Graben (Figure 1A.4.15).  The massive Shinomo cliff offset against Hakatai Shale by normal faulting looms straight ahead, and as you pass a major gully at the head of this minor tributary canyon, you jump across the main fault.  Look for several minor faults in the Hakatai and the Shinomo as you traverse this gullied fault zone.  Boulders of Shinomo and loose slabs of Hakatai are strewn along the trailside here exhibiting gorgeous sedimentary structures (Figure 1A.4.16).  Herringbone crossbeds make up layers within the Shinomo, formed by wave action, these features indicate that the origin of its sands was linked to beaches on a shoreline long ago.  Ripple marks adorn the planar surfaces of bedding in the Hakatai Shale, revealing the origin of its muds from deposition under slack-water conditions on even more ancient tidal flats.  At 5.98 miles (Map 1A.4.2), a left hand switchback on the far side of the amphitheater offers a superb view of the South Kaibab Trail dropping at breakneck speed all the way to the Colorado River (Figure 1A.4.17).  Careful observation of the rocks exposed along this line of sight shows that the outcrops below and to the right (east) of your location are made of Vishnu Schist, but to the left (west), red mudstones of the Hakatai overlie a brown-colored limestone cliff band of the Bass Formation.  Note that the Black Bridge across the Colorado River is anchored in Vishnu basement.  Looking above you, the same juxtaposition of crystalline basement against Supergroup rocks holds true.  At this location the trail has briefly crossed the Cremation Fault, the eastern bounding fault of the Cremation Graben as it switchbacks down and to the left (west).

Figure 1A.4.15 Cremation Graben

Figure 1A.4.15. A diagram modeling the complex relationships between faulted strata internal and external to the Cremation Graben, depicted as if the viewer were looking at the southern wall of the inner gorge from the north; the graben is bounded by two main normal faults and internally broken into two, smaller grabens separated by an intervening uplifted ridge.

Figure 1A.4.16 Herringbone Crossbeds in the Shinomo and Ripplemarks in the Hakatai copyrighted

Figure 1A.4.16.  Herringbone crossbedding in the Shinomo Sandstone, and ripple marks in the Hakatai Shale offer clues as to their depositional origins along coastlines of the Late Proterozoic; a quarter provides scale.

Figure 1A.4.17 Eastern bounding fault of the Cremation Graben, outcrops of Vishnu Schist lie against Supergroup rocks copyrighted

Figure 1A.4.17.  A jawdropping view of the final snaking descent of the South Kaibab Trail; evidence of the Cremation Fault, eastern bounding fault of the Cremation Graben, superbly on display here where outcrops of Vishnu Schist lie to the right (east), while Supergroup rocks lie to the left (west).

As you resume your descent, the trail quickly passes back into the Hakatai Shale, rounds to the left toward the main gully, and drops to a promontory at the top of the Bass Formation cliffs you saw earlier; you have traveled 6.33 miles from the rim (Map 1A.4.2).  The contact between the Hakatai Shale and Bass Formation lies just below this panoramic vista.  The view down canyon is quite breathtaking from here, and the geology expressed is worth contemplating for a few moments.  Look across the river to the mouth of Bright Angel Canyon to your right (northwest) and further downriver (Figure 1A.4.18).  The dark, rough walls of Vishnu basement nearest the Colorado are comprised of an unusually thick, vertically-oriented package of Brahma Schist, the metamorphosed equivalent of volcanic rocks stuffed deeply into ancient subduction zones during Middle Proterozoic island arc collision and construction of the southern margin of the Rodinian supercontinent 1.75 billion years ago.  Rising above the Vishnu basement, but confined to the walls of the inner gorge, a vertical stacking of Grand Canyon Supergroup rocks including the Bass Formation, Hakatai Shale, and Shinomo Sandstone exhibits down-to-the-west tilting and multiple offsets along normal faults that dip upriver toward Bright Angel Canyon.  The deformation here is related to growth of a small graben along the Bright Angel Fault.  This feature is probably the equivalent of the Cremation Graben, just on the opposite side of the river; dissection by the Colorado has simply chopped the original structure in half.  Extensional motion on the Bright Angel Fault caused a large crustal slab to tilt downward toward the northeast, while a smaller slab rotated back into the main fault from the west.  From your perch, you can observe that package of deformed Supergroup rocks fairly closely.  The smaller slab was fractured into several blocks that where rotated down and to the east into the main fault zone along multiple, minor fault splays paralleling the main Bright Angel Fault, thus tilting the normally horizontal sedimentary rock layers of the Supergroup down toward the west.  At least four normal faults can be observed in Figure 1A.4.18, each minor fault offsets the formations relative to each other, as well as the crystalline basement, with the greatest offset on these faults (the bounding fault) occurring furthest down river.  The prominent, dark cliff at the lip of the inner gorge (just below the Bright Angel confluence) is formed of resistant Shinomo Sandstone (Figure 1A.4.18).  The thinner, brown cliffs to the right resting on Brahma Schist are Tapeats Sandstone, cliffs which can be seen to pinch out against the more massive Shinomo outcrop.  This juxtaposition of rock units indicates that here too, the Shinomo formed an island in the Cambrian sea that was finally buried with a rise in sea level during later deposition of the Bright Angel Shale.

Figure 1A.4.18 Deformation of Supergroup rocks is readily observed from the South Kaibab Trail copyrighted

Figure 1A.4.18.  Deformation of Supergroup rocks is readily observed at a Bass Formation promontory on the South Kaibab Trail at mile 6.33; across the river and downstream of Bright Angel Canyon the Supergroup rocks are titled down-to-the-west and offset by several minor normal faults associated with extensional motion on the Bright Angel Fault some 750 million years ago.

Back on the South Kaibab Trail, negotiate two more switchbacks on your descent toward the Colorado River.  At the second of these sharp bends in the trail, your progress has taken you well within the Bass Formation.  Look to the left here at an outcrop of limestone beds alternating with thin, orange-red mudstones that stands about chest high; the waving banding within the denser limestones consists

of stromatolitic laminations; these are mats of fossilized cyanobacteria that grew in shallow-water, coastal settings during deposition of the Bass Formation approximately 1.2 billion years ago.  Stromatolites such as these represent some of the oldest life on earth!  Be on the lookout for more of these wavy, stromatolitic laminations to the right side of the trail within about 40 to 50 feet of the switchback.  Shortly, your tread passes back into dense, foliated crystalline rocks of the Vishnu basement where it remains all the way to trails end.

After negotiating a sharp, left-hand switchback, the trail recrosses the main tributary gully at 6.76 miles (Map 1A.4.2).  Here, the bed of the wash is comprised of a gorgeous breccia (Figure 1A.4.19), in this case a recent talus that has become cemented together by calcite minerals precipitated into the openings between chunks of rubble by the passage of groundwater.  Groundwater traveling through overlying layers of limestone dissolves the calcite into ions, carries the ions in solution downward where the water concentrates along a fault, and then bleeds out onto the surface in the bottom of the gully occupying the fault trace.  Dissolved ions in the water precipitate calcite minerals onto these rocky surfaces when exposed to the dry canyon air, effectively gluing the material together as the breccia seen  here.  Breccias such as this one are indicative of short-lived, gravity-driven transport related to mass wasting processes because the rock fragments cemented within the calcite matrix are coarse and angular.

Figure 1A.4.19 A recently formed breccia on the South Kaibab Trail copyrighted

Figure 1A.4.19.  A fine example of a breccia, this one formed in the bed of the main tributary gully at mile 6.76 on the lower South Kaibab Trail.

Passing the breccia outcrops, the South Kaibab Trail continues to descend on a short length of straightaway and then bends sharply right, and then left again through two tight switchbacks.  Here, you are offered a great view of the Black Bridge crossing the Colorado River much closer to the cliffs of Brahma Schist on the north side of the river (Figure 1A.4.20).  Note that the exposed rock comprising the cliffs is shot through with multiple stringers and blobs of pink Zoroaster Granite.  Lower Bright Angel Canyon just to the left is deeply incised into Vishnu basement, providing a paradise of features for a geological foray into the crystalline basement.  Just ahead, you reach the junction with the River Trail coming in from the left at 6.97 miles (Map 1A.4.2).  If you intend to return to the rim on the Bright Angel Trail, you want to bear left onto this trail, it will shave about two-thirds of a mile off of an already arduous hike.  If your destination is the North Kaibab Trail, Bright Angel Campground, or Phantom Ranch continue your down climb to the right.

Figure 1A.4.20 Vishnu Schist intruded by Zoroaster granite above the Black Bridge copyrighted

Figure 1A.4.20.  A strategic view of the Black Bridge over the Colorado River on the South Kaibab Trail near its junction with the River Trail; the cliffs just north of the bridge expose dark Brahma Schist copiously intruded by stringers and blobs of pink Zoroaster Granite.

Descend a few more switchbacks to a tunnel entrance for the south buttress of the Black Bridge; the trail levels out hereafter.  Cross to the north side of the river at 7.33 miles (Map 1A.4.2), and make a quick examination of the cliff just to the right of the bridge.  Your observations are rewarded by an excellent example of what geologists refer to as a zeolith; a “foreign” rock embedded within another (Figure 1A.4.21).  Here, a dark, ragged-edged chunk of Brahma Schist is incased in pinkish Zoroaster Granite; imagine the tumultuous setting deep in the crust where molten granitic rock intruded into the solid Vishnu along foliation planes and fractures, ripping lose chunks of the schist as in flowed upward and incorporating the rough blocks within the magma when it eventually solidified.

Figure 1A.4.21 Vishnu Schist inclusion within an intruding blob of Zoraster granite copyrighted

Figure 1A.4.21.  A zeolith of the metamorphic Brahma Schist lies embedded within an intruding blob of Zoraster Granite at the north buttress of the Black Bridge on the South Kaibab Trail.

From the bridge abutment, it is a short stroll to the end of the trail.  The trail hugs the border between cliff and sandy beach on the upriver margin of Bright Angel Creek’s delta.  Shortly, you pass the excavated foundations of an Ancestral Puebloan unit house and kiva on the edge of a terrace above the delta that probably served as a dwelling and communal center for an extended family group that once farmed the sandy soils of the stream’s bottomland (Figure 1A.4.22).  Ample water and plenty of sunshine would have made this location ideal for a small community such as this.  At 7.67 miles (Map 1A.4.2), your route reaches a bridge on the left crossing Bright Angel Creek; this is the juncture of the South Kaibab, North Kaibab, and Bright Angel Trails.  If your goal is Bright Angel Campground, cross the stream and take an immediate right onto the campground access trail and the welcoming shade of towering cliffs and cottonwoods.  Two large campsites serve the needs of seven to eleven hikers and dozens of smaller sites are available to groups of six or less; potable water and flush toilets offer true luxuries when it comes to camping below the rim.  If your destination is Phantom Ranch or the North Kaibab Trail, make a right at this juncture; and don’t pass up the opportunity for a cool glass of lemonade at the ranch catena.

Figure 1A.4.22 An Ancestral Puebloan unit house and kiva perched on the upper edge of the Bright Angel Creek delta copyrighted

Figure 1A.4.22.  The excavated foundations of an Ancestral Puebloan unit house and kiva near the Bright Angel Creek delta.

An overnight stay at Bright Angel Campground affords opportunities to relax and explore your surroundings.  A dip in Bright Angel Creek is sorely needed after a hot trek down from the rim, or in the afternoon heat of the inner gorge (Figure 1A.4.23).  The lush riparian vegetation along the stream corridor provides awesome shade and a picturesque contrast to the barren walls of rock that surround the campground.  The vegetation also offers stability for easily eroded, sandy stream banks prone to periodic flash flooding.  The metamorphosed and intruded Vishnu basement offers many fine features associated with its deeply buried past.  An excellent outcrop of Brahma Schist lies at the back of the unsheltered large group campsite that is worth your attention (Figure 1A.4.24).  Here, the schist contains wonderful examples of boudinage, a metamorphic feature that geologists believe can result from a later stage of heating that alters a previously solidified, tabular body of intrusive granitic rock to a taffy-like state.  Aligned parallel to foliation, this granitic ribbon was transformed into sausage-shaped bodies as it was stretched, allowing heated schist to ooze inward and occupy the gaps in between.  And when you have settled in for an evening meal, take the time to contemplate the sun-brightened cliffs of the Upper Granite Gorge along the south side of the river from your campsite (Figure 1A.4.25).  The dark Vishnu basement is comprised of Brahma Schist, contrasting with pods of pinkish, intruding Zoroaster Granite.  These crystalline basement rocks are overlain by bedded sedimentary rock layers resting atop the Great Unconformity, but not the Tapeats Sandstone as is most often the case.  Instead, the basal Bass Formation of the Grand Canyon Supergroup lies first in the sequence, overlain by the Supergroup’s Hakatai Shale, and finally, a thin cap of Tapeats rounds out the visible sequence.  And now the picture should be clear, you are looking at the Cremation Graben from the bottom up.  Enjoy your meal; you have experience enough geology for today.  Tomorrow, another day of discovery awaits!

Figure 1A.4.23 Bright Angel Creek near Bright Angel Campground copyrighted

Figure 1A.4.23.  While staying at Bright Angel Campground, be sure to enjoy a relaxing bath in the cool waters of Bright Angel Creek under a canopy of shady riparian cottonwoods.

Figure 1A.4.24 Boudenage comprised of Zoraster granite with Rama Schist copyrighted

Figure 1A.4.24.  Brahma Schist containing boudinage, sausage-like bodies of  rock formed by the heating and stretching of a previously solidified, tabular body of intrusive granite aligned parallel to foliation during a later stage of metamorphism.

Figure 1A.4.25 The south wall of Upper Granite Gorge from Bright Angel Campground copyrighted

Figure 1A.4.25.  On the south side of the river from Bright Angel Campground the cliffs of Upper Granite Gorge display evidence of the Cremation Graben; here, the rocks are comprised of crystalline basement, Brahma Schist intruded by pinkish, Zoroaster Granite and overlain by a rare slab of sedimentary rocks consisting of the Grand Canyon Supergroup’s Bass Formation and Hakatai Shale.

Hiking Trail Maps

Phantom Ranch, AZ (SW quarter) (Map 1A.2.1 and 1A.4.1)

Map 1A.4.1.  Shaded-relief map of the southwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.

Map 1A.4.2.  Shaded-relief map of the northwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.

Tonto Trail West (Tr1A.5)

The Grand Canyon’s Tonto Trail owes its existence to the dynamic forces of differential erosion which have worked for countless millennia on the soft and hard layers of stone comprising the Paleozoic sedimentary rock sequence that has been so marvelously exposed by the carving of the Colorado River.   When rivers carve downward through rock, they provide opportunities for other agents of weathering and erosion to expand upon the initial vertically oriented dissection, and where rocks are relatively weak, canyons spread laterally by a combination of physical and chemical weathering, mass wasting processes, and the headward and downward cutting of tributary streams.  In the Grand Canyon, this lateral expansion following the initial downward slice of the river is perhaps best observed in the eastern canyon, where it has created an open benchland at the rim of the Inner Gorge called the Tonto Platform.  Easily viewed from a number of South Rim overlooks, such as this view from the Rim Trail west of The Abyss at the head of Monument Creek Canyon (Stop #8 on the Red Route) (Figure 1A.5.1), the Tonto Platform is underlain by olive-green mudrocks; first, the muddy limestones to limey mudstones of the Muav Limestone, and followed by the mudstones and minor sandstones of the Bright Angel Shale.  These rocks have been eroded into a distinctive slope-forming layer, an obvious exception to the striking vertical cliffs that characterize most of Grand Canyon.  Weak layers consisting of mudstones like the Muav and Bright Angel are prone to weathering and erosion and tend to quickly retreat away from the downcutting channel, forming slopes and a broad valley; whereas strong layers consisting of cemented and/or interlocking grains of limestone and sandstone like the Redwall and Tapeats tend to stick around awhile, forming cliffs and a narrow incised valley.  Similarly, coherent, crystalline basement comprises the narrow Upper Granite Gorge below the Tapeats Sandstone.  Hence, the cyclopethean “step” is formed by the Muav Limestone and Bright Angel Shale slope separated by Redwall Limestone and Tapeats Sandstone cliffs.  Thus, it’s the geology that makes the Tonto Trail unique among Grand Canyon pathways.  The Tonto Trail follows this natural bench on a gently undulating transcanyon route for over 90 rough, unmaintained miles, from Red Canyon at its eastern end to Garnet Canyon at its western end. Where most trails descend from either North or South Rim to the Colorado River, the Tonto Trail provides an avenue for foot passage up and down the canyon, paralleling the course of the river and offering superb opportunities to see Proterozoic crystalline basement rocks by peering into the deeps of the Inner Gorge, as well as to gaze skyward to the ornately carved cliffs and ramparts of varicolored Paleozoic sedimentary rocks above.

Figure 1A.5.1.  The Tonto Platform, namesake and location for the Tonto Trail, forms a wide benchland that occupies the weak, mudstone slopes of the Muav Limestone and Bright Angel Shale sandwiched between resistant, cliff-forming Redwall Limestone above and Tapeats Sandstone below; the Tapeats rests on tough, crystalline Vishnu basement rocks of Upper Granite Gorge.

The trail’s sinuous length and significant stretches of sunny exposure forces all but the most intrepid Grand Canyon hikers to approach it in a series of installments, breaking the route down into several manageable sections that can be made into loops when joined by rim-to-river trails. A notable lack of reliable water makes hiking the Tonto Trail an always daunting task, but the sections between the Boucher Trail and the South Kaibab Trail are blessed with reliable water sources at not-to-distant intervals.  Personally, I wouldn’t hike the entire length of these combined segments in one outing, but this portion of the Tonto Trail does offer a reasonable degree of comfort not found elsewhere along the trail, and it is here that many hikers will get their first exposure to the unique nature of this exemplar transcanyon route.  I suggest two loop hikes of varying length and degree of difficulty: 1) using the section of Tonto Trail connecting the Boucher to the Hermit; and 2) using the section of Tonto Trail connecting the Hermit to the Bright Angel.  The first loop hike is the most difficult, made so more by its remoteness and the tortuous Boucher Trail connection than anything else; the second loop hike is long, but the Tonto Trail is easily followed and there are several designated campsites with potable water along the way.  Although both routes are essentially constrained to one topographic interval within the Grand Canyon, suggesting a monotonous undertaking, each offers an opportunity to reach the Colorado River along tributary canyons and to examine the canyon’s oldest crystalline basement rocks first hand; thus, their scenery and geology are quite remarkable.

Tonto Trail West (Boucher Trail Junction to Hermit Trail Junction) (Tr1A.5a)

This segment of the Tonto Trail could be used to complete a loop hike from Hermits Rest down the Boucher Trail and up the Hermit Trail (or vice-versa). It is about five waterless miles between Boucher and Hermit Creeks, but the trail is well-defined. Great inner canyon views of the lower Paleozoic sedimentary rock sequence, Great Unconformity, Proterozoic crystalline basement rocks, and an assortment of accessible travertine deposits, mainly near Travertine Canyon, provide geological diversion en route.  To begin this hike, make your way to the Boucher Trail-Tonto Trail junction in Boucher Canyon.  Presumably you will have camped at Boucher Creek the night before, so make the steep, but short climb from the Boucher Creek campsites to the “trailhead” as defined here (Map 1A.5.1).

The Tonto Trail veers left at the junction and continues to climb briefly along the north edge of the Boucher Creek side canyon, up onto the Tonto Platform.  Quickly rounding onto the first small promontory, be sure to look back up the tributary canyon you are exiting to view the large travertine mound partially blocking that side drainage; observation from here more readily shows that the travertine deposits literally form a down-slope-oriented drape over the horizontally bedded layers of mudstone and limestone in the olive-green colored Bright Angel Shale and Muav Limestone (Figure 1A.5.2).  The lush vegetation at the base of the drape on the east side of the tributary’s wash indicates a small spring.  The tributary canyon formed as a consequence of erosion along the Muav Fault; later, mineral rich waters migrated up to the surface along the floor and walls of the gully, where they evaporated in the arid desert air to leave calcium carbonate cement layer by layer, welding to itself and to rock fragments carried in the wash and eventually forming the mounded travertine drapestone.  The size of the mound suggests considerably heightened groundwater flow, much more so than at present, likely related to cooler, moister climatic conditions in the recent past.

Figure 1A.1.2.  Travertine deposits blocking the fault-controlled, left-hand tributary to Boucher Creek; drainage from springs feed by mineral rich groundwater migrating along the fault may explain the immediate source, although a much more significant flow related to wetter climatic conditions is necessary to explain massive scale of the deposits.

Continue onto the rolling expanse of the Tonto Platform proper and at about 0.54 miles (Map 1A.5.1), you reach the low amplitude drainage divide between Boucher Canyon and the Inner Gorge of the Colorado River.  To your right lies the cliffs of Redwall Limestone and Supai Group rocks below Whites Butte and Cocopa Point, the tributary canyon etched along the trace of the Muav Fault, the one down which the Boucher Trail makes its uncanny descent, lies in-between (Figure 1A.5.3).  The trail passes two small promontory ridges of Bright Angel Shale separating a gully draining into the Colorado eroded to the Tapeats Sandstone contact, a fairly typical pattern along this stretch of the Tonto.  On the second ridge, look down canyon, this is a good location to view the mouth of Boucher Canyon and its associated rapids on the Colorado River.  This view will stick with you for the next mile as the trail hugs the Tapeats rim.  After crossing the second ridge at 0.90 miles (a small sandstone knob should be located left of the trail) (Map 1A.5.1), stick to the upper trail when it divides, they will rejoin shortly.  The trail drops into another wash floored by Tapeats Sandstone at 1.06 miles (Map 1A.5.1), rubble here from a past landslide is cemented by travertine.  This is the first of several encounters with travertine deposits that you’ll make on this hike.  Pass through a second wash, then climb to the next ridge, look back into the dual washes at the travertine cemented landslide deposits below the trail; from this ridge, you can also see Boucher Rapids in the distance down canyon.  A second wash just ahead at 1.25 miles (Map 1A.5.1) contains a similar travertine deposit.  The source of these travertine deposits may be springs emerging from the Muav-Bright Angel Shale contact, or from within the Muav Limestone, but the colluvium covered slopes above the trail make this determination difficult to make.  The travertine deposits have been eroded and they do not appear to be actively forming today.

Figure 1A.5.3. A former student on the Tonto Trail below Whites Butte; in the background, the fault-controlled tributary to Boucher Canyon lies between Redwall Limestone and Supai Group cliffs below Whites Butte on the left, and Cocopa Point on the right.

The Tonto passes through a saddle in a fairly nondescript ridge at 1.56 miles (Map 1A.5.1); to the left of the trail, a knob of worn and scalloped travertine rests on Bright Angel Shale.  Close inspection of this travertine mound reveals that it has been fractured and broken in places, and there you can observe the internal layering of calcium carbonate buildup that accumulated over time with growth of the mound.  This small ridge also offers one of the nicest downcanyon views on the trail (Figure 1A.1.4).  The Tonto Platform’s bench-like geomorphology stands out in sharp contrast to the soaring cliffs of Redwall Limestone nearby, as well as the dark recesses of Upper Granite Gorge where the brown, horizontal layers of coherent Tapeats Sandstone form a bathtub ring-like cap on black, vertically foliated Vishnu basement.  The Great Unconformity forms the nonconformable contact between the two rock units, an erosional gap in earth’s history that here represents two major periods of tectonic upheaval and 1,200 million years of missing rock.  In the near view on the left, travertine deposits can be seen to drape over the Tapeats Sandstone; while in the distance down canyon, Boucher Rapids occurs at the mouth of Boucher Canyon where large debris flows periodically debouch into the Colorado River creating a blockage to flow and steeping of the river’s gradient.

Figure 1A.5.4.  The marvelous downcanyon view from the travertine outcrop at mile 1.55; so much geology to peruse, the layers of Paleozoic sedimentary rock and patterns of differential erosion resulting in multicolored cliffs and slopes, the bench-like Tonto Platform, the Great Unconformity, the crystalline basement rocks of Upper Granite Gorge, and blue-green ribbon of the Colorado River occasionally disturbed by patches of gregarious rapids.

Continuing forward on the Tonto Trail, near 1.84 miles (Map 1A.5.1), you pass through another ridge top saddle between outcrops of travertine draping over much older, horizontally bedded sedimentary rock.  Upslope from the saddle, a wonderful outcrop of travertine perched on a former slope eroded into Muav Limestone is exposed in vertical cross-section (Figure 1A.5.5).  After passing through the saddle, the trail enters Travertine Canyon; ahead you can see where other travertine deposits on a ridge nearer the main wash are draped down slope across flat-lying sedimentary rock.  Again, the source of these travertine deposits is a bit mysterious, but there certainly must have been a more ample flow of water from springs at the head of Travertine Canyon in the recent past.  Why did it stop (or at least become reduced to a trickle)?  A change to warmer, more arid conditions seems likely, although it is possible that the groundwater conduit system feeding the springs became blocked (by roof collapse?) and/or pirated and diverted to another location (over to Hermit Canyon perhaps?).

Figure 1A.5.5.  Travertine deposits draping much older, horizontally bedded Muav Limestone at the downriver entry to Travertine Canyon.

The trail swings through a small tributary draining the southwest side of the main canyon, passes the travertine covered ridge and then crosses the main wash at back end of Travertine Canyon near 2.29 miles (Map 1A.5.1).  Here, you drop into the wash just above a defile cut through brecciated travertine deposits that thickly coat the floor of the canyon in this area.  An outcrop on the right-hand wall (facing downstream) displays multiple layers of travertine incasing slope colluvium and coarse debris carried in the wash (Figure 1A.5.6a); each layer may represent passage of a debris flow followed by its gradual coating and cementing in place by travertine to form a breccia (Figure 1A.5.6b).  Beyond the wash, your route climbs to a low ridge comprised of a layercake of travertine deposits, then descends back to the Tapeats Sandstone rim at 2.58 miles (Map 1A.5.1).  Be sure to take a look back into the canyon; an excellent exposure on your side reveals thick layers of travertine draped downslope across the Tapeats rim (Figure 1A.5.7).  Close inspection shows verdant ribbons of moss and ferns clinging to the underside of the travertine drape, indicating that some spring activity still exists within the canyon.

Figure 1A.5.6.  Travertine deposits in the main wash of Travertine Canyon incorporate coarse, angular rocky debris related to slope colluvium and periodic debris flows (A); cementing of the debris forms a breccia (B).

Figure 1A.5.7.  Travertine drapes spectacularly downslope over the Tapeats Sandstone rim on the east side of the main wash in Travertine Canyon; the bright green vegetation to the left suggests that the springs are still partially active today.

At 2.98 miles (Map 1A.5.1), the trail veers close to the Tapeats rim and offers its final downcanyon view of the Tonto Platform and Upper Granite Gorge.  Probing views back into and across Travertine Canyon, reveal the expansive cover of travertine that drapes diagonally, downslope over the much older, horizontally bedded Paleozoic sedimentary rocks (Figure 1A.5.8).  Stop for a moment to take it all in, this is a gorgeous view point, especially in the morning when the sun is behind your cliff top position.  Rounding the promontory above the Colorado River at 3.11 miles (Map 1A.5.1), you are treated to yet another spectacular view; this time Hermit Rapids froths and swirls a mere 900 feet below (Figure 1A.5.9).  From this position, it is a relatively easy matter to contemplate the formation of Colorado River rapids.  Note the constriction of the channel caused by the bouldery debris dumped at the mouth of Hermit Canyon.  This material acts much like a dam, generating a calm pool above, and a significant change in gradient that accounts for the energy of the rapids.  These obstacles to the Colorado River’s flow would be quickly cleared, if they were not periodically renewed by deposition of fresh material brought in by debris flows cruising down high gradient tributaries such as Hermit Creek.

Figure 1A.5.8.  A final look at the travertine deposits of Travertine Canyon; from the photographs, it is easy to see that the travertine lies at an angle to the horizontally bedded Paleozoic sedimentary rock and was accumulated as a coating on those rock layers after they were eroded to nearly their current valley and slope configurations.

Figure 1A.5.9.  Hermit Rapids, formed at the mouth of Hermit Canyon, exemplifies the nature of Colorado River rapids; these geomorphic features occur as channel constrictions that steepen gradient and increase the energy of the flowing water and are caused by bouldery debris brought to the river from periodic debris flow events initiating in canyons tributary to the Colorado.

Now make your way past the rocky knob on the left-hand side of the trail (Figure 1A.5.10a).  This is the last major exposure of travertine on the Tonto Trail, and the outcrops wonderfully display the bulbous nature of the accumulated layers, looking much like flowstone formed in a limestone cave (Figure 1A.5.10b).  From here, the trail heads deep into Hermit Canyon, hugging the Tapeats rim and offering expansive views upcanyon as well as down the length of this major tributary (Figure 1A.5.11), a view which is dominated by the Tower of Ra on the opposite side of the river.  Near 3.86 miles, the Tonto swings into a large side canyon and crosses its wash at 4.23 miles (Map 1A.5.1).  Exiting this tributary, the trail returns to the Tapeats rim for great views into the Tapeats narrows, where Hermit Creek cuts a deep trench through a resistant sandstone.  Eventually, the trail reaches Hermit Creek camp at 5.09 miles; this location deserves at least a full day’s layover if ever there was one.  I recommend two nights, you’ll want to explore this area thoroughly, and enjoy a day hike down Hermit Canyon to the Colorado River and back.

Figure 1A.5.10. Travertine deposits at the tip of the promontory along the downriver entry to Hermit Canyon; these deposits display bulbous, laminated travertine, much like the flowstone observed in limestone caves.

Figure 1A.5.11.  Just one of many views as you make your way into the depths of Hermit Canyon on the Tonto Trail; come here often enough, and you can see the Grand Canyon in all her moods.

First, let’s take a look around the vicinity of Hermit camp.  Your natural inclination may be to head up the drainage to examine the contact between the Tapeats Sandstone and Bright Angel Shale where it is exposed along the stream; this can readily be accomplished and is not a bad choice of options.  As you work your way up the stream bed, you can generally avoid getting wet by sticking to the ledges formed by individual beds of Tapeats Sandstone.  Not more than a 100 yards upstream, sandstones begin to be replaced by mudstones, and within a few tenths of a mile, sandstone layers are nearly gone, having almost entirely been replaced by shale.  Turn around at a distinctively thick, crossbedded sandstone layer (Figure 1A.5.12), this is above as far as you need to go in order to understand the nature of this contact.  Geologists refer to this type of gradual replacement of the beds forming one type of sediment for the beds of another as an intercalated contact.  If you were to explore the upper canyon further, you would eventually transition through a similar intercalated contact between the Bright Angel Shale and Muav Limestone.  These contacts are indicative of gradually changing environmental conditions between laterally adjacent environments; the transition between sediments in a vertical stacking of rock types is known to geologists as Walthers Law.  Here, the gradual transition was brought about by rising sea levels in the Middle Cambrian, with the Tapeats Sandstone representing a beach or nearshore environment, the Bright Angel Shale a deeper water, lower energy setting on a proximal continental shelf, and the Muav Limestone deeper water still, on a more distal continental shelf where terrigenous sediment input was reduced allowing marine carbonates to accumulate.  The intercalated contacts suggest that the gradual deepening of water, the great Middle Cambrian marine transgression, was interrupted by brief periods of regression, when shallower water conditions returned intermittently during the overall rise in sea level.

Figure 1A.5.12.  My wife poses on the intercalated contact between the Tapeats Sandstone and overlying Bright Angel Shale as exemplified by this buff-colored, crossbedded sandstone layer sandwiched between greenish mudstones located just above the Hermit Creek campsite.

Return to Hermit camp at your leisure.  Another optional pursuit for understanding your local geology is a climb from camp on the Tonto Trail to get a better look around.  The way out of Hermit Creek is located near the composing toilet and large group campsite.  Take the trail to the Tapeats rim for a pleasant morning sunrise (Figure 1A.5.13); why sleep with views like these?  Follow the Tonto Trail briefly, until you reach the main ridge crest overlooking Hermit Canyon that sweeps down from Lookout Point.  Then simply ascend the ridgeline behind you toward Lookout Point as high as is practical (it becomes impassable once you reach minor cliff bands in the Muav Limestone).  However, you can reach a high enough position to get an excellent aerial survey of the entire lower Hermit Canyon to your north (Figure 1A.5.14).  This is a great location to see those intercalated contacts between the Tapeats, Bright Angel, and Muav described earlier.  While you are up here, examine the outcrops of sandstone interbeds within the Bright Angel Shale.  These layers contain superb trace fossils of worm borrows (Figure 1A.5.15a) and cruziana, or trilobite tracks (Figure 1A.5.15b).  Trace fossils are not the animals themselves, but they do preserve certain life activities or behaviors of those animals that geologist can use to infer not only what animal made them, but also what kind of environment them may have lived in.  Both of these types of animal commonly fed in wave-agitated bottom waters and are indicative of shallow marine conditions.

Figure 1A.5.13.  An upper Hermit Creek Canyon sunrise reveals the varicolored cliffs and slopes produced by differential erosion of Paleozoic sedimentary rocks; beauty and geology combined, what could be better?

Figure 1A.5.14.  The full expanse of lower Hermit Canyon observed from the ridgeline near Hermit camp that sweeps down from Lookout Point; Hermit Creek campsite can be seen in the lower left of the photo.

Figure 1A.5.15.  Trilobite trackways called Cruziana (A) and worm burrows (B) are common in the sandstone interbeds within the Bright Angel Shale; these specimens were found on the ridgeline just to the east and upslope of the Hermit Creek campsite.

Finally, let’s take a downcanyon trek to the Colorado River and Hermit Rapids.  This hike presents fond memories for me because it was my first exposure to the Great Unconformity’s 1,200 million year gap in time, and to the 1.7 billion-year-old crystalline basement rocks beneath!  There are two approaches to your hike; you can walk directly from the campsite downstream along the creek bed, or, you can take the official trail built by the Santa Fe Railroad when they established Hermit camp back in 1911.  To find that trail, take the Tonto Trail eastward out of Hermit Creek camp.  The Tonto climbs to the Tapeats rim, then remains fairly level as in passes the old Santa Fe Railroad “Hermit Camp”.  When you reach about four-tenths of a mile from your campsite, you should find a trail junction and sign post indicating “Hermit Rapids” (Map 1A.5.1).  The trail descends through the Tapeats Sandstone to your left and back to the bed of the stream.  The distance either way is about the same and I would recommend the high road in the morning and returning along the low road in the afternoon.

Starting from the Tapeats rim location, it is 1.43 miles to Hermit Rapids, or about 1.84 miles from the Hermit Creek campsite.  As you descend toward the river, you’ll pass several geological hot spots worth mention.  The trail first drops to the floor of the Tapeats narrows, where Hermit Creek has dissected a deep, steep-walled slot canyon through the sandstone beds of the Tapeats (Figure 1A.5.16).  Remnants of the former trail are best preserved here where it was blasted into the side of the canyon.  Contrast the confines of this defile with the wide open canyon of the Tonto Platform above; in the narrows, much of the stream’s energy is needed just to cut downward through the resistant Tapeats and little is left over for any lateral erosion.  Scarp retreat has aided widening of the canyon above where mudstones of the Bright Angel Shale and Muav Limestone are susceptible to weathering and mass wasting processes.  A hike through the narrows offers good opportunities to examine the composition and structure of the Tapeats Sandstone.  Herringbone crossbedding is common to the Tapeats and is indicative of oscillatory currents produced by wave action (Figure 1A.5.17a).  Geologists refer to sandstones like this one as immature because they are comprised of locally sourced material that has undergone little transport, and classifying it as a feldspathic arenite because it is dominantly comprised of quartz and feldspar grains.  The Tapeats is coarse-grained and contains abundant feldspar grains and some lithic fragments (Figure 1A.5.17b), two characteristics that imply little modification from its sight of mobilization (probably eroded by wave action from nearby outcrops of exposed Zoroaster granitic rocks).  Careful observation also reveals thin veneers of mud and coarse gravels plastered onto the sandstone some tens of feet above the stream bed in places (Figure 1A.5.18); these offer evidence of large debris flows that passed down canyon in times past.  Clearly, you wouldn’t want to be here when one of these roared through the confines of the Tapeats narrows.  The debris flow material is cemented to the lower walls of the narrows by salts that have been subsequently mobilized by groundwater and have leached from the sandstone to form the whitish streaks, small stalactites, and encrusting salt crystals seen in Figure 1A.5.18.

Figure 1A.5.16. The Tapeats Sandstone narrows of Hermit Canyon; note the remains of the old Santa Fe railroad trail constructed on the right-hand side of the narrows (as you face upcanyon).

Figure 1A.5.17.  The Tapeats Sandstone commonly displays herringbone crossbedding (A) indicative of oscillatory currents produced by waves; and its composition is immature, as indicated by its coarse-grained texture and abundance of feldspar grains and lithic fragments in its matrix.

Figure 1A.5.18. Debris flows deposits plastered to the lower walls of the Tapeats narrows attest to the dangerous conditions that can prevail during flashfloods (A), imagine being trapped in the narrows when a debris flow swept downcanyon such as the one indicated by the height of the deposits seen here; these deposits are cemented to the sandstone walls by salts leached from the rock by groundwater.

Near the end of the narrows, large blocks of Tapeats Sandstone form a somewhat scary to think about pile of rubble to the right of the trail; just beyond, the canyon begins to open up and suddenly, on your immediate left is a spectacular exposure of the Great Unconformity (Figure 1A.5.19).  Here, the Tapeats Sandstone lies directly on vertically foliated Vishnu Schist, an erosional gap of 1.2 billion years gone missing from earth’s history.  Strange to contemplate, but there are actually more missing rocks in the Grand Canyon than there are rocks.  Take a close look at the outcrop as you pass by, this is a fabulous opportunity to see the nonconformity so well exposed, and here you can observe a paleosol preserved at the contact.  Paleosols represent the original subaerially exposed weathering surface (on which a soil formed), quit a rare instance actually, that the soil was not removed by the same wave action that generated the immature Tapeats Sandstone sediment discussed earlier.  Examine the Vishnu Schist in the area, it is not difficult to make out the NE-SW orientation of its foliation, a by-product of NW-SE oriented squeezing of the deeply buried sediments during metamorphism associated with island arc subduction 1.8-1.7 billion years ago.  The Vishnu Schist in nearby outcrops contains huge crystals of muscovite mica (Figure 1A.5.20), and its content has been interpreted as the metamorphosed equivalent of volcanic sediments stripped from the rising island arc and stuffed down an oceanic trench some 40 km (25 miles) during subduction.

Figure 1A.5.19.  The Great Unconformity exposed in the left-hand (western) wall of lower Hermit Canyon; here, the contact between Tapeats Sandstone and Vishnu Schist forms a nonconformity, a hiatus representing 1.2 billion years of missing rock record.

Figure 1A.5.20.  Large crystals of muscovite mica in the Vishnu Schist of lower Hermit Canyon.

The boles of the earth are truly on display in this marvelous canyon.  Continue your trek toward the river, as the tributary widens and deepens, gorgeous views never cease (Figure 1A.5.21).  Keep an eye pealed from marvelous outcrops of Zoroaster Granite, the other crystalline basement rock common to the Inner Gorge.  The Zoroaster is correctly named a granitic complex because it is not a singular body of igneous rock.  It represents numerous plutonic intrusives injected into the overlying, metamorphosing Vishnu basement in the Mesoproterozoic during subduction and mountain building on the ancient Rodianian supercontinent’s southeastern margin.  In lower Hermit Canyon, exposures of Zoroaster Granite record several pulses of plutonic activity, with Zoroaster even intruding Zoroaster upon occasion (Figure 1A.5.22).  In Figure 1A.5.22a, an older outcrop of Zoroaster Granite is intruded by a younger felsic pegmatite dike; and in Figure 1A.5.22b, close examination of the dike reveals a beautiful matrix of large feldspar, quartz, and hornblende crystals.

Figure 1A.5.21.  Gorgeous views dominated by the Tower of Ra await the visitor to lower Hermit Canyon.

Figure 1A.5.22.  Outcrops of Zoroaster Granite, a term used to describe all granitic intrusives in the crystalline basement of the Grand Canyon, are common along the stream course in lower Hermit Canyon; (A) shows a felsic pegmatite dike intruding older Zoroaster Granite and (B) displays the pegmatite’s composition, large crystals of feldspar, quartz, and hornblende.

Eventually, you can hear the roar of Hermit Rapids ahead, and after a few more twists and turns of the stream channel as it navigates a course through foliated Vishnu basement, the canyon abruptly opens onto a boulder strewn delta at the confluence of Hermit Creek with the Colorado River.  The most direct route to the river is to follow the stream bed, past an invitingly shady campsite on the left, and on to open water.  Hermit Rapids is quite an impressive site; find yourself a perch amongst the rocks and watch the thunderous crashing of the Colorado (Figure 1A.5.23).  If you are lucky, a raft trip will pass by while you enjoy a lunch; watching those tiny craft take the rapids helps to place the river’s powerful flow in perspective.  Hermit Rapids has formed where deposition of bouldery debris flows pouring down Hermit Canyon have choked the river’s channel, effectively steepening the stream gradient and the speed of the flowing water.  The power of the flowing water is mesmerizing, but the day is only getting warmer and it’s over a mile and three-quarters back to camp; return at your leisure.

Figure 1A.5.23.  The goal of any hike down lower Hermit Canyon, Hermit Rapids on the Colorado River, formed where deposition of bouldery debris flows have choked the channel, effectively steepening the stream gradient and the speed of the flowing water.

Assuming that you have thoroughly immersed yourself in what Hermit Canyon has to offer, it’s now time to return to the South Rim via the Hermit Trail (or consider continuing on to Monument Creek for more incredible geology).  To reach the junction with the Hermit Trail, climb to the Tapeats rim, eastbound on the Tonto Trail (Map 1A.5.1).  You quickly pass the trail to Hermit Rapids on your left at 5.50 miles (from the Boucher Trail junction) and ascend a subdued ridge of Bright Angel Shale to a prominent view of lower Hermit Canyon at 5.80 miles (Map 1A.5.1).  The canyon is bordered by the remarkably bathtub-ring-like Tapeats Sandstone, whose horizontal brown layers stand in sharp contrast to the northward widening and deepening defile carved into Vishnu basement as it approaches the Colorado River’s Inner Gorge.  Shortly, the trail swings to the right around at small ridge and offers a good view of the Hermit Trail’s Cathedral Stairs directly to the east.  Follow this path upslope to the right with your eyes, the Hermit disappears behind a promontory of Redwall Limestone, the breakdown slope there, your avenue of escape, is formed along a splay of the Hermit Fault.  Continue to 6.30 miles and the junction between the Tonto and Hermit Trails (Map 1A.5.1).  If you are headed out, turn right and onto the Hermit Trail; but take the left fork if you have not had enough of the Tonto Trail and your next destination is the campsites at Monument Creek.

Tonto Trail West (Hermit Trail Junction to Bright Angel Trail Junction) (Tr1A.5b)

The portion of the Tonto Trail that connects the Hermit to the Bright Angel is the most popular and best maintained section of this scenic transcanyon route.  It is most commonly used to complete a loop hike from Hermits Rest down the Hermit Trail and back to the South Rim at Grand Canyon Village on the Bright Angel Trail (or vice-versa).  It is nearly thirteen and a quarter miles between end points, but since you may be starting from Hermit Creek campsite on the western end, add about another mile and a quarter to your journey.  The trail often follows the rim of the Tapeats Sandstone, which affords awesome views of Upper Granite Gorge, as it navigates in and out of three major tributary canyons: Monument, Salt, and Horn.  Excellent campsites with permanent, drinkable water are found at the Hermit Creek and Indian Garden ends of the route, but also at Monument Creek (about four miles from Hermit Creek).  Horn Creek offers a secluded alternate campsite (compared to Indian Garden), but don’t drink, cook with, or bath in the water!  The Lost Orphan Mine operated at the head of the Horn Creek drainage during the 1950s, pulling out profitable uranium ore, but permanently contaminating the canyon’s perennial waterway with radioactivity in the process.  My recommendation would be to overnight at Hermit Creek, Monument Creek, and Indian Garden, but an even more spectacular trip might include overnight camping at Hermit Rapids and Granite Rapids found at the mouth of Hermit and Monument Canyons, respectively.  Great inner canyon views of the lower Paleozoic sedimentary rock sequence, the Great Unconformity, and the Proterozoic crystalline basement rocks offer up a plethora of geological diversions along your course of travel.  Monument Canyon is one geological wonderland that you don’t want to miss, be sure to reserve a full day to explore the lower canyon from the Monument Creek campsites to the Colorado River and back.  To begin this hike, make your way to the Hermit Trail-Tonto Trail junction in Hermit Canyon (6.86 miles in on the Hermit Trail); presumably, you will have camped at Hermit Creek the night before, roughly one and a quarter miles west of this “trailhead” junction at the base of the Cathedral Stairs (Map 1A.5.1).  Then head to the left (northeast).  Alternatively, many hikers make the roughly nine-mile trek down from Hermit’s Rest all the way to the Monument Creek campsites on the first day, loping off close to three miles of the Tonto Trail in the process (if this is you, pick up the Tonto Trail at the aforementioned junction, veering to the right instead).

From the trailhead junction, the Tonto Trail quickly climbs 0.13 miles to a low saddle in a ridge comprised of Bright Angel Shale that separates Hermit Canyon from a small tributary draining to the Colorado below Cope Butte (Map 1A.5.1).  Look carefully for slabs of sandstone in the Bright Angel Shale that exhibit ripple marks, produced by wave agitation of sea floor sediments.  To your right, note that the base of Cope Butte consists of olive-green Bright Angel Shale overlain by Muav Limestone in a gradually steepening slope; combined with the brownish Tapeats Sandstone which you can see exposed in the side canyon below the saddle, these three rock units will be your constant companions on this transcanyon trek.  Muav on Bright Angel, Bright Angel on Tapeats; the three-unit package represents deposition of sediments in gradually deepening water during the world-wide Middle Cambrian marine transgression.  The Bright Angel Shale here contains cliff-bands of sandstone indicative of shallower, higher energy conditions (Figure 1A.5.24), their presence within the shale of this sedimentary rock unit indicates fluctuating sea levels during the overall marine transgression.  Cope Butte lies to your right, erosion along several splays of the Hermit Fault have dissected it into a series of buttresses that some believe resemble a “cathedral” (the cathedral of the Cathedral Stairs fame in the lower Hermit Trail).

Figure 1A.5.24.  Cliff-bands comprised of sandstone crop out within the Bright Angel Shale indicative of shallower water, higher energy conditions during the Middle Cambrian marine transgression that generated the Tapeats Sandstone-Bright Angel shale-Muav Limestone sequence.

The trail then navigates through a precipitous little side canyon formed on the outer edge of Cope Butte, alternately descending nearer the Tapeats Sandstone, then ascending to an even higher saddle of Bright Angel Shale on the tributary’s northern lip at 0.97 miles (Map 1A.5.1), along a route with significant exposure at times (watch your step).  The Tonto Platform all but disappears along this section of the trail because abundant sandstone layers in the Bright Angel Shale in this area make the unit a temporary cliff-former.  The downcanyon view of Upper Granite Gorge is marvelous from this second saddle (Figure 1A.5.25).  The delta formed of bouldery debris flow material at the mouth of Hermit Creek is plain to see, its obvious constriction of the Colorado River causing the frothy Hermit Rapids seems quite obvious. Observe the dark crystalline basement rocks of the Inner Gorge distinctively capped by the thick, brown Tapeats Sandstone, its horizontal layers standing in sharp contrast to the near vertical foliation of the metamorphic Vishnu basement.  The contact between these units is an erosion surface, the Great Unconformity, a nonconformity representing about 1,200 million years of missing earth history.  The resistant Tapeats Sandstone forms the foundation of the Tonto Platform, the gently undulating benchland comprised of the weak, easily eroded, grayish mudrocks of the Bright Angel Shale and Muav Limestone upon which the Tonto Trail makes its circuitous route.

Figure 1A.5.25.  The Tonto Trail below Cope Butte offers a breathtaking downcanyon view of the Tonto Platform, Great Unconformity, and Upper Granite Gorge.

Continue through the saddle and begin a gradual, downward-sloping traverse back to the level of the Tapeats Sandstone as you make your way deeper into Monument Canyon; slabs of Bright Angel Shale along this section of trail display excellent worm burrows, another feature suggesting its marine origins. The Tonto reaches an excellent overlook of the lower canyon and Granite Rapids on the far side of a small wash at 1.21 miles (Figure 1A.5.26a).  Continue onward, views of the upper canyon’s sheer walls comprised of thick Kaibab Limestone, Toroweap Formation, and Coconino Sandstone known as “The Abyss” gap in the distance.  Navigate through several small washes on the canyon’s western side; the last of these small ravines and the largest, has formed along the NW-SE oriented trace of the Monument Fault.  Keep this observation in mind as we’ll return to it later, but for now consider the intervening promontories between the washes, each offering great views of the crystalline basement rocks and Great Unconformity revealed in lower Monument Canyon’s depths.    The canyon exposes a bewildering array of crystalline basement rocks, prominently laced by flesh-colored, sheet-like Zoroaster intrusives (Figure 1A.5.26b), perhaps the most interesting geological phenomena it has to offer.

Figure 1A.5.26.  The depths of Monument Canyon viewed from the Tapeats-rim-hugging Tonto Trail above (A); close examination of the canyon walls reveals excellent exposures of foliated Brahma and Vishnu Schist intruded by an array of Zoroaster granitic rocks (B).

At 1.50 miles (Map 1A.5.1), your route climbs from the fault-controlled side wash to a drainage divide separating the main canyon from its right-hand (western) tributary to provide your first views of the canyon’s namesake, “The Monument” (Figure 1A.5.27a), an impressive pillar of Tapeats Sandstone standing isolated from the surrounding cliffs.  Follow the trail into Monument Creek’s western fork, and you’ll soon descend into its rocky wash.  Seasonal springs feed a verdant growth of lush grasses in this tributary, making it quite unique.  Be on the lookout for cairns indicating the trail which skirts along the right side of the wash and the base of the Tapeats cliff; don’t follow the wash as it leads to an impassible pouroff.  The trail leads to a point separating the main canyon’s two forks and to a great view of the Monument (Figure 1A.5.27b).  Practically standing under it, you can see that the Tapeats Sandstone of the spire actually rests on a large mass of pinkish Zoroaster Granite; contrast this with the surrounding Tapeats cliffs which, for the most part, lie on grayish Brahma and Vishnu Schists.  After rounding the point, a spur trial joins the Tonto from the left signed for “Granite Rapids” at 2.28 miles (Map 1A.5.1); more on that option later.  An observant eye will note that at this junction, you are now standing on coarsely crystalline granitic rock of the Zoroaster Complex, the Great Unconformity lies just upslope to your right.  Just ahead, another spur trail on the right leads to a dead end at the canyon’s large group campsite; the main trail slants downward onto a wide stretch of sandy-floored valley in Monument Canyon and makes a beeline for several nice smaller campsites close to the creek.  The large campsite has marvelous views at sunrise (Figure 1A.5.28), even if you don’t have seven or more in your party, it’s worth a quick trip up there when it’s unoccupied.  It also has the advantage of being tucked up against an overhanging Tapeats cliff and is well shaded all afternoon; and the views upcanyon get better and better as the afternoon wears on (Figure 1A.5.29).

Figure 1A.5.27.  Monument Canyon’s unusual spire of rock known as “The Monument” as seen from the Tonto Trail in the canyon’s west fork (A); The Monument is comprised of Tapeats Sandstone resting on an intrusive body of Zoroaster Granite (B).

Figure 1A.5.28.  A Grand Canyon sunrise from the large group campsite in Monument Canyon.

Figure 1A.5.29.  A late afternoon view of the South Rim’s famed Mohave Point from the large group campsite on Monument Creek.

Once you have had a chance to settle in at your respective campsite; it’s time to do some exploring.  Monument Canyon is a geologist’s paradise; with a nearly limitless inventory of crystalline basement rocks to examine, well expressed faulting, and a few youthful geomorphic features to consider.  Save a trek to Granite Rapids at the mouth of Monument Canyon for a day hike, there’s plenty to see, there’s shade at the river, and the Colorado’s chilly water is inviting on a hot day.  In the immediate vicinity of camp, there are two options that beckon to the adventurous spirit and geologist alike: the readily accessible slot canyon just below your sandy-floored valley, and a lengthier excursion (actually several related excursions) to explore evidence of the Monument Fault.  If you’ve hiked over from the Hermit Creek campsites, you should have ample time to explore all or some of both.  If you’ve hiked all the way in from Hermit’s Rest, I would recommend the slot canyon for now, its shade and cool pools of water are a welcome relief on a hot afternoon.  Let’s start there.

The inner gorge of lower Monument Canyon hosts a spectacular little slot canyon sculpted into a complex of Middle Proterozoic gabbro-diorite-granodiorite crystalline basement rock that at times seems otherworldly in its beauty, in the geology on display, and in the sheer enjoyment of a frolic through it on a hot day.  And parents, its way better than Disneyland (Figure 1A.5.30)!  But all fun aside, the slot canyon offers great opportunities to observe some very special rocks.  Two easy paths lead into its upper end; one can simply hike down the streambed from the main concentration of campsites, or one can take a signed spur trail on the east side of the Tonto Trail located about half way between the composting toilet and the large group campsite.

Figure 1A.5.30.  Monument Creek’s slot canyon is a marvel of geological wonders and a fabulous place to frolic on a hot day; my own children can attest to that!

As you enter the slot canyon from its upper end, you are immediately treated with two Grand Canyon rarities.  First, on the right-hand side, exposed in the canyon wall just above the beginning of the narrows, is a unique outcrop of mafic igneous rock (Figure 1A.5.31a).  The coarsely crystalline, greenish-black rock (Figure 1A.5.31b) incased in pinkish Zoroaster Granite is a large xenolith (or cluster of xenoliths) of gabbro carried upward within the more felsic magma from considerable depth in the earth’s crust; the xenolith’s mafic composition prevented the rock from melting in the relatively low temperature felsic magma.  Xenoliths such as this one are unusual in the Zoroaster, but they attest to the significant depths from which the magma was generated and they preserve rare glimpses of the earth’s deep crust.  Where the slot canyon begins to close into a true narrows, look for an odd outcrop of travertine, a carbonate deposit, coating the granite on the left-hand wall of the creek  just above the water level (Figure 1A.5.32a).  Careful observation of the immediate area reveals other smaller travertine drapes and several small seeps draining from the granite; these latter springs are probably related to groundwater migrating along fractured rock associated with the Monument Fault.  Look closely at the travertine, the carbonate originates from the evaporation of mineral-rich groundwater exposed to the hot, dry air; the coating here is comprised of many small terracettes (Figure 1A.5.32b), a feature common to flowstone in limestone caves.

Figure 1A.5.31.  Crystalline basement rocks of the Monument Creek slot canyon consist of relatively rare gabbro, diorite, and granodiorite; (A) displays an outcrop containing gabbroic xenoliths, while (B) shows the coarse-grained texture and mafic composition of the gabbro.

Figure 1A.5.32.  Travertine deposits coat granitic rock at the upper end of the slot canyon narrows (A), these deposits and related seeps indicate active groundwater flow from the fault-fractured crystalline basement rocks; the travertine coatings occur as numerous small terracettes, similar to flowstone found in limestone caves (B).

Now make your way through the slot canyon.  There are many pools, small water falls, and slickrock surfaces to entertain you.  Deeper in the narrows, there are also numerous awesome outcrops of another Grand Canyon rarity, gneiss (Figure 1A.5.33a); actually described, mapped and dated by geologists as the 1733 million-year-old Trinity Gneiss.  These rocks are highly metamorphosed granodiorite, baked at temperatures and pressures where pervasive reorientation, rearrangement, and regrowth of solid mineral crystals perpendicular to the prevailing maximum pressure field, as well as partial melting and crystallization of more felsic minerals, were combined to generate the banded, marble-like textures observed (Figure 1A.5.33b).  Unlike the more common dikes and larger plutonic bodies of Zoroaster, the alteration of the granodiorite is so thorough as to cause near total recrystallization of the original igneous intrusives, separating darker, more mafic minerals from light-colored felsic minerals into distinctive bands during the high grade metamorphic process.  These gneissic rocks contain abundant flesh-colored feldspar which implies that the rock’s originator was rich in the mineral feldspar, not unlikely given the intermediate igneous intrusives common to the slot canyon.  The narrows section of the slot canyon ends where the stream course makes an abrupt right angle bend at the base of The Monument.  The rock exposed in the left wall (forming the bulk of the rock on which The Monument rests) is comprised of a more typical felsic Zoroaster Granite, the slot canyon’s abrupt bend probably linked to foliation or a contact between rocks types within the crystalline basement.  From here, the slot canyon widens and within a few dozen yards, loses its “wonderland” appeal.  Return to your campsite at your own pace.

Figure 1A.5.33. The walls of the Monument Creek slot canyon expose marvelous granitic gneisses formed by the intense metamorphism of crystalline basement rocks of the Zoroaster Complex here (A); detailed examination of the gneiss indicates that feldspar is common suggesting the original intrusive igneous rock was a granite or granodiorite.

For an alternate or additional geological venue, searching for evidence of the Monument Fault may be to your liking.  The trace of this fault runs counter to the adjacent Hermit Fault and is confined to the central portion of Monument Canyon; its orientation is NW-SE, suggesting that the two faults may form a conjugate fault set produced by the same tectonic forces.  Displacement on the fault is up to the northeast.  Your first order of business should be to examine the evidence of faulting near at hand.  Take a short hike to the large group campsite (if you’re not already camped there), and look northeast, directly across the valley to the Tapeats Sandstone cliff.  Notice the rockfall filling a section of the wash; on the cliff directly above, you should be able to discern that the layers of Tapeats Sandstone are bent downward toward you (Figure 1A.5.34a).  The bending you see here is a small monoclinal fold produced by reverse motion on the Monument Fault at depth in association with Late Cretaceous to Early Tertiary Laramide compressional forces.  The fault does not appear to be exposed, but upward displacement of the crystalline basement on the northeast side of the fault resulted in the folding of the overlying Paleozoic strata.  Now take a short hike over to the rockfall for a close look up at the folded sandstones (Figure 1A.5.34b).  Both perspectives should satisfy you that the fold is real, and the cause was upward displacement to the northeast.  Navigate your way around to the back side of the rockfall pile for some unique, albeit tangential, evidence of the Monument Fault.  Here, the Tapeats Sandstone is coated in salt deposits, some forming beautiful soda straws and stalagmites (Figure 1A.5.35); and because faults often act as conduits for the movement of groundwater, the presence of these salt deposits in this location can hardly be coincidence.  In all likelihood, water, enriched in salts has been leached from the fault shattered rock only to evaporate in the aridity of the canyon air, thus leaving behind the salt deposits.

Figure 1A.5.34.  Folding of the Tapeats Sandstone exposed in the eastern wall of Monument Canyon’s inner gorge is associated with up-to-the-northeast displacement on the Monument Fault, most recently, a reverse fault associated with Laramide compressional tectonics; (A) shows the folding in the Tapeats sandstones from the large group campsite in Monument Canyon, (B) shows the folded rocks nearly parallel to the fold axis from the base of the Tapeats cliff.

Figure 1A.5.35.  The salt deposits depicted here indicate seepage of groundwater enriched in salts, probably along fractures in the rock associated with the Monument Fault.

Next, we’ll get an aerial view and more complete picture of the Monument Fault by hiking a short section of the Tonto Trail up to the Tapeats Sandstone rim on the north side of the canyon.  Make your way to the cluster of smaller designated campsites beyond the composting toilet and cross the Monument Creek wash at the sign (officially 2.51 miles from the Hermit-Tonto Trail junction; Map 1A.5.2).  Just upstream, you should find a well-marked exit point on the left and the trail to the Tapeats rim.  At 2.76 miles (Map 1A.5.2), you swing left as you approach the rim, passing through tilted and disrupted Tapeats Sandstone layers, discolored by groundwater movement; before you lose your view of the inner canyon, look back downstream.  A protrusion of the Tapeats cliff on the east side of the valley is distinctly notched, with a squat tower of sandstone perched on the end of the protruding cliff (Figure 1A.5.36); folded sandstone layers in the Tapeats lie directly below the saddle formed between tower and main cliff face.  The notch eroded into the protrusion of Tapeats Sandstone falls in line with a gun-sight-like aperture on the skyline; in between, there is a water-carved notch in the Tapeats cliff on the west wall of the inner canyon (that same ravine you traversed on your way to camp).  This alignment traces the NW-SE oriented Monument Fault (and its associated monoclinal fold).  Continue hiking on the Tonto Trail, in which soon climbs above the Tapeats and into Bright Angel Shale briefly as it traverses a broad promontory.  Shortly, the trail drops back to the Tapeats rim, crosses two gullies in rapid succession, and returns to the Bright Angel Shale on a second broad promontory at 3.12 miles (Map 1A.5.2).  From this promenade, look across the inner gorge of Monument Creek to the Tapeats Sandstone cliff slightly northwest of your position.  A gully sweeps down from the Muav and Bright Angel slopes joining that ravine you crossed earlier in the day.  Follow the ravine as it pours off the Tapeats rim, and directly below, you should see a pronounced kink in the sandstone layers of the Tapeats (Figure 1A.5.37); evidence of the Monument Fault on the west side of the canyon.  The beds are folded upward on the right, indicating that displacement on the fault is up to the northeast.  Return to Monument Creek camp from here.

Figure 1A.5.36.  The NW-SE alignment is easily traced by examining the orientation of the folded Tapeats Sandstone here, at the photographer’s position, and through the gun-sight-like ridges in the middle and background distances ahead.

Figure 1A.5.37.  The prominent kink displayed by the Tapeats Sandstone layers in the western wall of Monument Canyon’s inner gorge indicates up-to-the-northeast displacement related to reverse movement on the Monument Fault.

Finally, if you haven’t satisfied your curiosity of the Monument Fault yet, we’ll hike up the main wash about three-tenths of a mile past a significant tributary joining the wash from the right, and past abrupt left-, then right-hand bends in the main channel.  When the wash bends back sharply to the right on the upstream end of the second bend and straightens out for some distance ahead, you have gone far enough.  Turn around, and examine the Tapeats Sandstone outcrop right at the bend you just passed through, the distinctively tilted sandstone layers should be a well-recognized theme by now (Figure 1A.5.38).  The beds are titled down to the left indicting the same up-to-the-northeast displacement on the Monument Fault; reverse faulting caused by the Late Cretaceous to Early Tertiary Laramide compressional regime.  You have earned your junior ranger badge at this juncture, head back to camp for a well-deserved rest.

Figure 1A.5.38. Observation of folding in the Tapeats Sandstone associated with the Monument Fault at a final location upcanyon from the Monument Creek campsites shows the same up-to-the-northeast, reverse displacement on the fault related to Laramide compression.

If you can spare an extra day at Monument Canyon on your backpacking trip itinerary, an extra day hiking to its confluence with the Colorado River would be well worth it.  The geological features unearthed by the carving of lower Monument Canyon’s inner gorge are a delight to behold and ponder, and the scenery is spectacular.  Once again, I recommend an early start, there’s much to see and the inner canyon gets hot by midday.  Return to the trail junction described at mile 2.28 when you were hiking in to the Monument Creek campsites; this spur trail avoids the slot canyon and starting out with wet feet.  You will want to wear your boots because most of the trek is in loose gravels comprising the dry streambed of the main wash.  The spur trail first crosses a narrow ridge that forms not only the physical divide between the main canyon and its western fork, but also the contact between two major bodies of crystalline basement rock; granodiorite crops out on the upcanyon side and Brahma Schist on the downcanyon side, all of which is injected with Zoroaster Granite.  Figure 1A.5.39 shows the complexity of these relationships, and the trace of the spur trail as viewed from the Tapeats rim on the eastern side of Monument Canyon.  Passing to the left side of “The Monument” (the pillar’s base formed of Zoroaster), the trail offers a great view up Monument Canyon from the narrows of the slot canyon all the way to Mohave Point.  Upon reaching the outer edge of the rock rib, it then descends quickly into the lower end of the western fork of Monument Creek on a series of five tight switchbacks through black Brahma Schist.  Note the large cairn piled at the wash, you’ll be returning this way in several hours.  A short walk down the streambed brings you to the main channel of Monument Creek.

Figure 1A.5.39.  A narrow ridge of crystalline basement rock comprised of granodiorite, Brahma Schist, and Zoroaster Granite forms the divide separating the main channel of Monument Creek from its western tributary; the spur trail into the inner gorge and Granite Rapids snakes its way across the ridge and down the near side just right of “The Monument”.

Look around, at first the walls surrounding you are comprised of the very dark, foliated Brahma Schist, yet another Grand Canyon rarity; but if you were to walk upcanyon, you would soon enter the lower end of the slot canyon and the composition would change to the gabbro-diorite-granodiorite complex described earlier.  Head downcanyon; about a quarter of a mile down the wash, you should cross a large patch of Brahma Schist exposed in the streambed.  At this location, look up and slightly to the left at the west wall of the canyon; a fault is well exposed, separating Brahma Schist below, from Vishnu Schist injected with ribbons of Zoroaster Granite above (Figure 1A.5.40).  Note the tight folding in the Vishnu/Zoroaster; the folds are oriented NE-SW and parallel the general pattern of foliation in the crystalline basement.  The composition of the crystalline basement rocks abruptly changes from Brahma Schist to Vishnu Schist and Zoroaster Granite from here to the river.  We have seen three transitions the between rock types in the crystalline basement of Monument Canyon and these contacts also parallel trend of the foliation; when combined, these features suggest a compressional tectonic regime oriented NW-SE.  Geologists use this information to reconstruct ancient plate tectonic interactions, which at the time these rocks formed 1.8-1.7 billion years ago, indicate that collisional plate boundaries were oriented NE-SW and compressional stress was orient perpendicular to the boundaries, or NW-SE.

Figure 1A.5.40.  The fault controlled contact between two major bodies of crystalline basement rocks in lower Monument Canyon; the Brahma Schist lies below and upcanyon of the fault, while the Vishnu Schist and Zoroaster Granite lie above and downcanyon of the fault.

Continue onward, there are plenty of gorgeous rocks to gawk at along the way.  In about half a mile below the fault, look to the right-hand side of the wash at eye level.  Just ahead, the main channel cuts sharply to the right around a 90° bend, but here, the base of the canyon wall displays tightly folded Vishnu Schist (Figure 1A.5.41).  The folded schist consists of two layers, one dark, the other a rusty brown.  Follow the dark band of schist from right to left across the outcrop, it plunges into the streambed, then rises abruptly, only to fold over and plunge back into the bed of the wash. The brownish colored layer of schist is scrunched into a tight fold between the folded dark band on the right, then rises up, over, and down the folded dark band in the middle, only to be folded upward and sheared by a fault on the left side of the outcrop.  The axis of these folds is oriented NE-SW, parallel to the general foliation pattern, suggesting that this folding was coincident with overall formation of foliation in the Vishnu basement.

Figure 1A.5.41.  Tight folding in the Vishnu Schist produced in tandem with, and parallel to, the general pattern of foliation.

A few steps down the wash take you to another wonderful outcrop, and a feature common to the remainder of the inner canyon.  At eye level, right at the sharp turn in the streambed, the canyon wall is comprised of dark Vishnu Schist that has been intruded by pinkish, coarsely crystalline Zoroaster Granite (Figure 1A.5.42a).  The Zoroaster is folded into a distinctive “S” shape, indicating that the intrusion is itself metamorphosed.  In fact, many of the exposures along the canyon walls display similar ribbons of granite that have been altered post-emplacement (Figure 1A.5.42b), which indicates that plutonism was consequent with metamorphism during the mountain building processes that generated these crystalline basement rocks.  Walk another tenth of a mile or so and start looking for another amazing outcrop at eye level on the right-hand side of the wash.  This exposure may just be the finest outcrop of crystalline basement in the entire Grand Canyon; it offers a unique, three dimensional view of an intricately folded granitic dike incised in Vishnu Schist (Figure 1A.5.43a).  The dike is clearly oriented nearly parallel with the foliation in the schist which is also folded (Figure 1A.5.43b), indicating that the dike was initially intruded as a flat sheet along the plane of foliation and then the entire body of rock hosting the intrusion was folded accordion style, compression oriented more or less perpendicular to the wall of the canyon.  The fold axes within the dike are oriented NE-SW, similar to the foliation of the Vishnu Schist itself, so folding occurred concurrently with regional subduction and mountain building in the Middle Proterozoic.

Figure 1A.5.42.  (A) and (B) provide two examples of the countless Zoroaster granitic intrusives that exhibit folding subsequent to their emplacement, implying that they were subjected to the same compressional stresses and metamorphic regime as the Vishnu Schist that they intrude; this indicates that the intrusion of magma and metamorphism were coincident.

Figure 1A.5.43. Housed within the depths of Monument Canyon lies this little gem of an outcrop; a three-dimensional exposure of a folded Zoroaster granitic dike incased within foliated Vishnu Schist (A), the folds are oriented NE-SW, parallel to the general foliation pattern exhibited by the schist, which itself has been metamorphosed, presumably by the same event that folded the dike (B).

Two more right-angle bends downcanyon bring you to a widening of the valley floor where the bouldery deposits of past debris flows have accumulated as stream terraces along the channel margins (Figure 1A.5.44a).  The coarse, poorly sorted nature of the material is readily observed (Figure 1A.5.44b), suggesting strongly a mechanism transport characterized by high energy.  Normal stream flow, or even stormwater flows, would likely be lacking in sufficient velocity or discharge, but mudflows and/or debris flows would have what is necessary.  The physical features of the Grand Canyon’s many tributaries can provide the necessary inducements for mass wasting events such as these: steep, sparsely vegetated slopes; abundant mudrocks and alternating layers of weak and strong rock types vulnerable to weathering and erosion; high gradient, narrow, bedrock floored stream courses that naturally channelize flows; and a climate dominated by two distinct wet periods, spring snowmelt and a summer monsoon.  Mass wasting events such as these can impose a significant hazard when hiking in the confined quarters of these canyons, avoid them if rain threatens!  Debris flows also contribute the primary scouring agent for incision of tributary channels; and they provide an essential material for the construction of rapids on the Colorado River.  As with most other tributaries, Monument Creek has built a large bouldery delta at its confluence with the Colorado out of debris flow materials.  This debris has partially blocked the river’s flow forming Granite Rapids (Figure 1A.5.45a), constricting the channel and steepening its gradient to increase the velocity, and shallowing the channel at the same time, which makes it more interesting for river runners.  Upstream of the constriction, one usually finds a deep, quiescent pool because the rapids acts like a dam of sorts, elevating the river level and causing more tranquil flow (Figure 1A.5.45b).  The rapid itself is a very temporary geomorphic feature that would be rapidly removed by the river’s erosive power if it were not for those debris flows periodically roaring down side canyons to freshen the supply of material to the tributary delta.

Figure 1A.5.44.  Bouldery sediments accumulated as stream terraces in lower Monument Canyon are the product of debris flows that periodically sweep down tributaries such as this one (A); the size of the material in transport attests to the powerful energy conditions associated with these mass wasting processes (B).

Figure 1A.5.45.  Granite Rapids, formed similar to most rapids on the Colorado River, is caused by the constriction of flow and steepening of channel gradient associated with deposition of debris flows issuing from tributary canyons (A); the debris flow-generated delta formed at the confluence with the river causes a damming effect, forming a tranquil flowing pool upstream paired with the rapids.

All good things must come to an end; and thus, your geological tour of Monument Canyon must end too.  It is time to push on and make your way to Indian Garden Campground in Garden Canyon.  Today’s hike is nearly ten miles, and while the terrain covered by the Tonto Trail is not difficult, it is exposed to the afternoon sun.  You will want to reach your destination before lunch; my advice, start early, before sunrise.  Return to the cluster of smaller designated campsites beyond the composting toilet at the upper end of Monument camp and cross the Monument Creek wash at the sign as before.  This is 2.51 miles from the Hermit-Tonto Trail junction (Map 1A.5.2).  Find the well-marked exit point just upstream on the left-hand side.  You might notice that the channel is dry here, as it was below the slot canyon.  In part this is because the porous gravels comprising the streambed shallow the water such that the flow may be just below the surface; however, about 100 yards down the wash from here a spring gurgles up from the stream bed to provide the camp and slot canyon with its water.  The spring is probably controlled by the position of the Monument Fault where it crosses the valley floor.

Since this part of your day’s journey has already been described when we went exploring for evidence of the Monument Fault, and you may well be hiking this section of trail in the predawn light, we’ll skip to the chase and pick up when we reach the overlook on the second broad promontory underlain by Bright Angel Shale already discussed at 3.12 miles in from the Hermit-Tonto Trail junction (Map 1A.5.2).  From the overlook then, continue north, dipping back into yet another Tapeats-floored wash, then around a small ridge.  The trail bends abruptly to the right here at 3.23 miles on the near side of a deep ravine and climbs steeply upslope through the small valley at the head of the ravine to a saddle in a broad ridge of Bright Angel Shale in about two-tenths of a mile (Map 1A.5.2).  This is your last view of Monument Canyon and its namesake pillar of stone.  In the early morning light, the amphitheater backed by steep cliffs at the head of the canyon known as The Abyss is quite prominent.  The Toroweap and Hermit Formations, normally slope-formers, are comprised on abundant sandstones in this area and so they form coherent cliffs instead; combined with the Kaibab and Coconino units, this makes for an impressive drop without much of a break in slope.

Angle to the right and begin an undulating traverse through two small canyons draining from the outer edge of a wide ridge connecting the South Rim capped by Supai Group rocks called The Alligator.  As you descend gradually into the first drainage, your route passes a spur trail on the left at 3.83 miles signed for the Cedar Spring campsites (Map 1A.5.2).  Cedar Spring issues from the base of the Bright Angel Shale, but provides water only seasonally so don’t rely on it (especially if it was a dry winter – not uncommon these days).  After crossing the bed of the second drainage, the trail makes a beeline toward the northeast along the eastern edge of this small canyon, remaining more or less at the Tapeats-Bright Angel contact.  Hugging the Tapeats rim, a great view of Granite Rapids and down Upper Granite Gorge opens up at 4.55 miles (Map 1A.5.2), and from there, the Tonto Trail climbs gradually into Bright Angel Shale to a point separating your small, unnamed canyon from much larger Salt Creek Canyon ahead.  At 4.76 miles (Map 1A.5.2), your first upcanyon view on the day’s trek opens up; the Tower of Set lies nearly due north, directly across the canyon opposite your position, Cheops Pyramid is directly ahead to the northeast, with Isis Temple in between.  The long arm of Redwall Limestone capped by Dana Butte blocks your view due east.  Continue east, just ahead the trail clings precariously to the Tapeats rim, but views into the Inner Gorge are stellar.

Now begins a long traverse of Salt Creek Canyon; actually two drainages, Salt Creek is the main one and is crossed first, but a second smaller canyon runs parallel to it and is contained within the arm of Redwall Limestone capped by Dana Butte that you must circumnavigate in order to continue upriver on the Tonto Trail.  At 5.04 miles (Map 1A.5.2) your route crests a small ridge to offer the first bold view of Salt Creek Canyon.  Hopi Wall, Salt Canyon’s headwall looms spectacularly in the distance; framed by Mohave Point on the left and Hopi Point on the right, it is formed of sheer cliffs of upper Paleozoic rocks like The Abyss before it.  From here, the trail makes a lengthy traverse almost due south into the canyon, sometimes near the Tapeats rim, and sometimes higher, within the Bright Angel Shale.  Salt Creek Canyon has eroded a deep trench into light-colored crystalline rock, apparently a large body of felsic igneous intrusives.  The exposed rock is actually the main body of the 1733 million-year-old Trinity Gneiss.  Recall the gneiss you saw in the Monument Creek slot canyon, which was just a small outlier of this much larger pluton.  This metamorphic rock is believed to be one of the oldest intrusive bodies in the Grand Canyon, the Trinity Granite, injected into Vishnu Schist during the early stages of island arc subduction, and thus significantly altered over time.  It now forms one of many plutonic bodies in the canyon collectively called the Zoroaster Complex.

At 5.93 miles (Map 1A.5.2), you reach the west bank of Salt Creek; a spur trail to the right leads about 50 yards upcanyon to the Salt Creek campsites, complete with composting toilet, but no water.  To the right, the main trail descends several switchbacks down to the wash.  Walk downstream briefly to pick up the trail leading up and out on the east side to begin an extended traverse back out of Salt Canyon to the Tonto Platform encircling the base of Dana Butte.  If you have timed your journey just right, a marvelous sunrise view down the length of Salt Creek Canyon awaits when you crest the second of two small ridges ahead (Figure 1A.5.46), the Tower of Set, with its radiating arms of Redwall Limestone and cap of Supai Group rocks delights the senses.  The trail crosses the divide separating the Salt Creek drainage from its smaller eastern companion at 6.32 miles (Map 1A.5.2), and then you must circumnavigate two large side tributaries before reaching the Tonto Platform again.  Wrapping around the north wall of the second side tributary, you reach a fabulous perch at 7.68 miles (Map 1A.5.2) overlooking both Salt Canyon to the southwest and the Colorado’s Upper Granite Gorge to the west and northwest.  Be sure to take in the views; first, gap at your downcanyon view of the Inner Gorge (Figure 1A.5.47).  The Tonto Platform’s benchland underlain by mudrocks of the Bright Angel Shale and lower Muav Limestone contrast sharply with the confining cliffs of Tapeats Sandstone below and Redwall Limestone above.  The sedimentary rocks in turn stand out starkly against the dark recesses of Upper Granite Gorge’s vertically foliated Vishnu basement, the Great Unconformity forming the erosional contact between the two major rock bodies, a 1.2 billion year gap in the rock record representing uncounted millennia of tectonic upheaval and stripping of the continent.  Now look back the way you have come, the South Rim at the head of Salt Creek Canyon is quite beautiful, the Hopi Wall, framed by Mohave Point and Hopi Point, and The Alligator are glorious in the early morning sunlight (Figure 1A.5.48).  The South Rim is capped by the buff-colored Kaibab Limestone and Coconino Sandstone cliffs, and the entire canyon is enfolded by the soaring arms of brick-red Supai Group rocks and Redwall Limestone, a splendid contrast of light, color, and relief.

Figure 1A.5.46.  A view down Salt Creek Canyon offers a gorgeous view of the Tower of Set, heighten by the glen of a Grand Canyon sunrise.

Figure 1A.5.47.  Upper Granite Gorge and the Tonto Platform viewed from the Tonto Trail as it makes its final exit from Salt Creek Canyon’s eastern slopes below Dana Butte.

Figure 1A.5.48.  The head of Salt Creek Canyon is crowned by the South Rim’s Hopi and Mohave Points comprised of buff-colored Kaibab Limestone, which stand in sharp contrast to the great red arms of Supai Group rocks and Redwall Limestone that frame it.

Incidentally, the picture-perfect setting presented by Figure 1A.5.48 affords a great opportunity to test your knowledge of Grand Canyon Paleozoic stratigraphy (Figure 1.3).  All seasoned hikers to the canyon should be able to recognize their sedimentary rock units based on the pattern of differential erosion they display.  A good discussion of the entire sequence can be found in my SEDIMENTARY ROCK FORMATIONS OF THE GRAND CANYON REGION, but for a primer, let’s begin at the beginning with the basal Paleozoic unit, the brown, distinctly layered Tapeats Sandstone, a cliff-former due to its characteristically resistant quartz-rich composition.  The Tapeats represents the initial beach and near shore phase of a global-wide Middle Cambrian marine transgression.  Overlying the Tapeats is the slope-forming Bright Angel Shale comprised on olive-green mudstones deposited in deeper water on the gradually flooded Middle Cambrian continental shelf of ancient western North American craton.  Rapid weathering and erosion of this unit (combined with the slow pace of the breakdown of the Tapeats) is chiefly responsible for the development of the Tonto Platform on which you stand.  Completing the Middle Cambrian sequence is the Muav Limestone.  The Muav, also generally olive-green, begins as mudrock and ends as limestone, essentially deposited as limey mudstones transitioning to a muddy limestones on the deeper end of a warm-water continental shelf; the transition in sediments explains the gradually increasing slope toward the top of this unit.

Although the stratigraphy includes the Devonian Temple Butte Formation next, that rock layer is thin and patchy and not readily observed in this view.  On the other hand, any visitor to the Grand Canyon would recognize the massive red cliffs of the Redwall Limestone, a Mississippian age rock unit accumulated in a tropic marine shelf environment.  The red color of the unit is deceiving because up close the limestone is a typical dull gray, but weathering and erosion of the overlying rock units, which are composed of oxidized, red sediments, the Redwall has become “red-washed” through the ages.  Overlying the Redwall Limestone, again we have an indistinct, discontinuous sedimentary rock unit, the Mississippian Surprise Canyon Formation.  This rock layer was deposited in sinkholes, caves, and stream valleys incised into a subaerially exposed Redwall, which were then flooded by an advancing sea.  Above the Surprise Canyon, we have the Supai Group, consisting of four sedimentary rock formations deposited on an arid coastline during the Pennsylvanian and early Permian, alternating between desert sand dunes and nearshore sandy marine deposits as sea level fluctuated rapidly; the uppermost cliff-former is the predominantly sandstone layer called the Esplanade Sandstone, formed in a coastal desert erg.  The red color of these sedimentary rock units is the result of oxidation during subaerial exposure, and because the formations alternate between mudstones and sandstones, the Supai Group forms a package of alternate slopes and cliffs.

Overlying the early Permian Esplanade Sandstone, is yet another slope-former, the Permian Hermit Formation.  The Hermit is a distinctly red, primarily mudrock unit deposited in a low relief, coastal plain setting of meandering rivers and deltas.  Its sediments were oxidized and desiccated by a return to aridity in the late Permian with deposition of the buff-colored Coconino Sandstone.  This resistant, cliff-former is characterized by classic desert-sand dune-generated, megacrossbedded, fine-grained, quartz-rich sandstones.  Above the Coconino lies the Toroweap Formation.  Accumulated in the late Permian, this unit is a mixed bag of mudstones, sandstones, and limestones, with minor interbedded evaporate deposits, all suggestive of fluctuating sea levels in an arid, shoreline environment.  The final layer deposited in the Paleozoic is the late Permian Kaibab Limestone, representing a return to full marine conditions on a tropical continental shelf.  Now let’s continue on our way, we have essentially reached the half-way point in our day’s travels, the sun is up, and we still have Horn Creek Canyon to contour our way around.

As you round the thin, northward extension of Redwall Limestone below Dana Butte, the Tonto Trail maintains a classic Tonto Platform stride with gentle undulations along the Tapeats-Bright Angel transition, and cliff-hugging views of the Inner Gorge.  At 8.37 miles (Map 1A.5.2), the trail reaches a low saddle in the Bright Angel Shale after climbing through a major landslide comprised of Redwall Limestone blocks.  This promontory provides a marvelous upcanyon view of the Tonto Platform perforated by the dark chasm of Upper Granite Gorge (Figure 1A.5.49); Brahma Temple and Zoroaster Temple occupy the skyline on the left, and O’Neill Butte along Cedar Ridge on the far right, while the double pinnacles and flat-topped mesa in the center distance are Angel’s Gate and Wotans Throne.  Should you feel so inclined, a short walk to the top of the small knob on your left offers a geological treat and an eye-popping view of the Inner Gorge.  From the knob, look straight north across the gorge to the broad, Tapeats Sandstone-capped divide between two obvious drainages (Trinity Creek lies to the left and Ninetyone Mile Creek to the right).  Follow the Tapeats cap westward from the Ninetyone Mile Creek side, a fresh-looking landslide scar adorns the Vishnu basement rocks not far inward.  At the head of this scar lies an outcrop of greenish-black ultramafic igneous rock sandwiched between cliffs of vertically foliated Vishnu Schist (difficult to photograph early in the day).  Geologists call this rock peridotite, outcrops of ultramafic rocks such as this one are very unusual among the crystalline basement rocks of the Grand Canyon, formed when dense, iron-rich minerals like olivine and pyroxene settle from the melt to collect at the bottom of a magma chamber long before the more felsic mineral do.  When the lighter magma is injected upward, chunks of this early formed rock can be incorporated within it to be carried along for the ride, where they end up residing incased within larger bodies of igneous rock that is more intermediate to felsic in composition.

Figure 1A.5.49.  The Tonto Platform dissected by Upper Granite Gorge, the upcanyon view greeting you at mile 8.37 on the Tonto Trail on the promontory at the end of Dana Butte’s long arm of Redwall Limestone; how many landmarks can you identify?

Back on the Tonto Trail, continue into a small drainage on the northeast flank of Dana Butte; as you pass through the wash and climb the Bright Angel slope on the far side, Dana Butte’s eastern face, comprised of a massive cliff of Redwall Limestone, hoves into view (Figure 1A.5.50).  Note the olive-green ledgy cliff-bands at its base, an excellent exposure of the Muav Limestone, much of which is usually in slope.  Just ahead, the trail reaches a saddle in a broad ridge of Bright Angel Shale at 9.06 miles (Map 1A.5.2) that forms the drainage divide between Horn Creek and the small side drainage below Dana Butte.  An excellent cross-canyon view from here reveals an interesting story (Figure 1A.5.51).  First, orient yourself properly; the triangular tower on the skyline in Cheops Pyramid.  Now, in the foreground, as expected, you can see that the Tapeats Sandstone caps the crystalline basement rocks of the north wall of the Inner Gorge.  But notice than the sandstone thins from about 300 feet thick to about one-tenth of that toward the center of your view (directly beneath Cheops Pyramid).  A closer look indicates that a mound of Zoroaster Granite actually protrudes upward where the Tapeats thins, this is not a coincidence.  The protruding granite knob likely formed an island as the rising Middle Cambrian seas lapped against it, eventually succumbing to the waves and becoming buried by beach sands.  You may notice a bump to the left and behind the cliff exposure; this bump is crystalline basement rock poking above the Tapeats Sandstone cover, probably just a northwest extension of the “island” already described.  Take a closer look at Cheops Pyramid which is formed of Redwall Limestone; what’s wrong with this picture?  Answer: there is an extra cliff-forming rock layer at the base of the edifice on which Cheops Pyramid is perched.  The cliff’s elevation lies above the Tapeats Sandstone exposed by cutting of the Inner Gorge that you observed in the foreground, so either that cliff in the background has been elevated, by a fault perhaps, or it’s not Tapeats Sandstone.  Turns out, there is no fault, the cliff is formed of Shinomo Sandstone, a Late Proterozoic sedimentary rock belonging to the Chuar Group of the Grand Canyon Supergroup.  Looking very closely, you can see that the Shinomo cliff is actually tilted downward to the northeast, and following it to the west, it rises gradually until it disappears to the left side of the block on which the Isis Temple sits. This tilted block is covered in Bright Angel Shale, but not Tapeats Sandstone, implying that it formed a large “island” in the Cambrian sea, much larger than the aforementioned blip we see in the foreground, and was not inundated until sea level rose much higher in Bright Angel time.

Figure 1A.5.50.  Dana Butte’s towering edifice founded in the Muav Limestone’s grungy greenish muddy limestones and crowned by impressive red cliffs of Redwall Limestone as viewed from the Tonto Trail just west of Horn Creek Canyon.

Figure 1A.5.51.  Cheops Pyramid, the Vishnu Schist and Shinomo Sandstone, and “islands” in the rising waters of the Middle Cambrian sea.

As you continue hiking, the Tonto Trail gradually descends from the ridge, passing through greenish, glaconite-rich Bright Angel mudrocks bored through by countless tubular worm burrows, returning to the Tapeats rim and to your first look into Horn Creek Canyon’s formidable depths at 9.36 miles (Map 1A.5.2).  In the bottom of the canyon you can see where Horn Creek’s two forks join at the level of the Great Unconformity; below that, much of the crystalline basement rocks exposed in the lower canyon are part of the 1713 million-year-old Horn Creek Granite, one among many plutons in the Zoroaster Complex.  From here, your route grips the edge of the canyon as it weaves its way into Horn Canyon’s western fork to cross the dry wash at 9.73 miles (Map 1A.5.2).  The trail rounds a sharp ridge covered in colluvial debris dividing west and east forks of the canyon, then makes its way to Horn Creek and the Horn Creek campsite at 10.18 miles (Map 1A.5.2).  This is a pretty little camp, and much more secluded than you’ll find at Indian Garden Campground; and there is a composting toilet located on a short path above the campsite for your convenience.  However, as I indicated earlier, do not make use of the water in Horn Creek; it is contaminated by radioactive waste from the spoils of the Orphan Mine, once operated in the headwaters of this drainage. The mine produced $40 million worth of uranium ore during its hay days in the 1950s, although it began as an on-again-off-again copper mine in the 1890s.  The copper and uranium ore formed when mineral-rich groundwater percolated through a porous, tubular-shaped accumulation of cemented rubble known as a breccia pipe.  The pipe and its breccia are part of the patchy Surprise Canyon Formation, in this case deposited in a cave system formed in the top of the Redwall Limestone when it was exposed to weathering and erosion.

From Horn Creek camp, hike north along the east side of the canyon, ascending higher into the Bright Angel Shale.  At 10.52 miles (Map 1A.5.2), on the crest of a west-sloping ridge formed where Horn Creek Canyon swings northwest, then back to the northeast, be sure to look back into the canyon.  Horn Creek Canyon’s multifaceted headwall, adorned by three major South Rim battlements of Kaibab Limestone is boldly on display (Figure 1A.5.52); on the far left is Maricopa Point, in the middle Powell Point, and on the far right is Hopi Point.  Once again, the classic Paleozoic stratigraphy presents itself in the varicolored cliffs and slopes of this gorgeous canyon.  A last look down the axis of lower Horn Creek Canyon soon presents itself (Figure 1A.5.53) as the trail now bends eastward to round the promontory below The Battleship (the Redwall and Supai Group buttressed ridge separating Horn Creek and Garden Creek Canyons).  Great views upcanyon of the Tonto Platform unfold as you hike, although the trail is much higher in the Bright Angel Shale here and the recesses of the Inner Gorge are not on display.  As you swing around the final bend heading south, Garden Canyon and its famed Indian Garden sweep across your view (Figure 1A.5.54).  Although not obvious from the trail, an examination of the topographic map (in the shade at Indian Garden) will reveal that Garden Canyon is distinctly linear, evidence that it has been carved along a fault, the Bright Angel Fault, which continues on up straight-as-an-arrow Bright Angel Canyon to the northeast.  Thus, these two canyons form a pair aligned in tandem with the NE-SW trending Bright Angel Fault which, like many of its companions in the region, has be active since the Late Proterozoic.

Figure 1A.5.52.  The headwall of Horn Creek Canyon; the South Rim, capped by the buff-colored Kaibab Limestone, is adorned by three turrets of stone, from left to right, they are Maricopa Point, Powell Point, and Hopi Point.

Figure 1A. 5.53. A final look down Horn Creek Canyon offers a picturesque view of the Inner Gorge and three major Grand Canyon landmarks on the horizon, Cheops Pyramid, Isis Temple, and Shiva Temple; stepping up and back toward the North Rim, each tower or mesa is capped by Paleozoic sedimentary rocks higher in the section.

Figure 1A.5.54.  First view of Garden Canyon from the Tonto Trail; the cottonwoods along Garden Creek mark the location of Indian Garden Campground.

Finally, at 11.99 miles (Map 1A.5.3), the Tonto Trail merges with the trail heading to and from Plateau Point, more of a broad avenue really, and suddenly you know that you have emerged from the wilderness.  Get ready to return to the accoutrements of civilization, including all of its people in various shapes, sizes, and levels of preparedness (people watching on the trails ahead can be so interesting)!  Continue on into Garden Canyon, near 12.72 miles you reach the destination of your day’s adventure, Indian Garden.  Here, the Tonto joins the Bright Angel Trail; Indian Garden Campground in up the trail and to your immediate right.  If you have further plans to take in a Plateau Point sunset and/or you intend hiking to the South Rim from here, check out my trail guide for the Bright Angel Trail.

Hiking Trail Maps

Map 1A.5.1.  Shaded-relief map of the northwest quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

Map 1A.5.2.  Shaded-relief map of the northeast quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

Map 1A.5.3.  Shaded-relief map of the northwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.