Grand Canyon National Park offers a free (well, assuming you’ve paid your park entrance fee), energy efficient shuttle-bus service to many locations in the Grand Canyon Village area (including the town of Tusayan, AZ just south of the park).  Visitors can select from several color-coded transit route options depending on where they wish to go and what they want to see (Figure 1A.1).  The blue (Village) and orange (Kaibab/Rim) routes begin and end at the park Visitor Center, while the red (Hermits Rest) transit route begins and ends at the Hermits Rest/Village Transfer Stations.  A bus route offering free transport between Tusayan, AZ and the visitor center (the purple route depicted in Figure 1A.1) is also available.  Two trails also wind their way along the South Rim in the vicinity of Grand Canyon Village, often overlapping with each other and taking in the same destinations reached by the shuttle routes (Figure 1A.1).  The paved Greenway Trail provides a scenic biking route bar none, while the Rim Trail offers an excellent opportunity to stretch your legs and take in the sights without the relief (and strain) normal to the rim-to-river trails.  The park service shuttles are equipped to carry bikes, making it a very real possibility for families with younger children to bike portions of the Greenway Trail and hop on a bus when the need arises.

Figure 1A.1 Grand Canyon Village Transit Routes

Figure 1A.1.  Shuttle transit routes and hiking/biking trails in the Grand Canyon Village area, South Rim, Grand Canyon National Park.

 

Geological route descriptions in Field Trip 1A correspond to park service shuttle transit routes; and since my hope is that you’ll be riding a bus and leaving your personal vehicles at your lodging or campsite, I describe the routes by bus stops rather than by mileage.  Of course, bike riding on the Greenway Trail or hiking the Rim Trail would be the ideal way to experience the canyon.  Since there is significant overlap between these trails and the transit routes, I do not describe the trails individually as is the norm throughout the rest of my website; but instead, I insert references to trail locations and travel distances within the dialogue describing the shuttle-bus touring routes.

 

Purple (Tusayan) Route

The two-way purple transit route begins at the main shuttle terminal at the Grand Canyon National Park Visitor Center and ends at the Grand Canyon IMAX Theater in Tusayan, AZ (Figure 1A.1).  The shuttle will take you in and out of the park, so if you are staying in Tusayan, it provides stress-free access to the park and helps reduce congestion and vehicular pollution.  From the visitor center, you can take additional transit routes that access all of the South Rim’s canyon overlooks and interpretive sites in the Grand Canyon Village area, as well as plenty of opportunities for lodging, shopping, and dining.  One segment of the Greenway Trail parallels the purple transit route, allowing bike access to the park; although it is 6.6 miles one-way between the Grand Canyon Visitor Center and the IMAX Theater in Tusayan (four of it is currently unpaved).

 

Blue (Village) Route

The blue transit route is the primary utility corridor of the shuttle system (Figure 1A.1); you won’t actually see the Grand Canyon from anywhere along this route, but it affords vital access to both of the principle canyon “overlook” routes (the orange and red transit routes), the Greenway and Rim Trails, and other important destinations such as Mather Campground, the Backcountry Information Center, the train station, and various lodging, shopping, and dining options.  The description which follows is by no means comprehensive, please visit the Grand Canyon National Park website for more detailed information.

 

Stop #1     Refer to Map 1A.1.  The Grand Canyon National Park Visitor Center hosts the main shuttle terminal in the park (where the blue, orange and purple transit routes merge).  Before taking the westbound blue transit shuttle, make some time for the visitor center.  Here, you have access to interpretive displays and one-on-one conversations with rangers, as well as the Grand Canyon Association bookstore; bicycle rentals and a great coffee shop finish off the ledger of opportunities.  From this location, you can also walk out to Mather Point and join the Rim Trail, start a bike trip on the paved Greenway Trail (also used by pedestrians), or catch a ride on the orange transit route.

 

Stop #2     Market Plaza Westbound.  A quick walk from this stop takes you to Market Plaza.  You can find lodging, shopping, and dining at Yavapai Lodge, and the Canyon Village Market offers a deli, a surprisingly well-stocked little grocery store, camping gear, and plenty of souvenirs, as well as the park’s only bank and post office.

 

Stop #3     Shrine of the Ages (Westbound).  This stop provides access to the park headquarters, a large auditorium for ranger-lead interpretive programs, and access to the Rim Trail.

 

Stop #4     Refer to Map 1A.2.  Train Depot.  Here, the shuttle stops just across the street from the Grand Canyon Railway station at the beginning of the Grand Canyon Village National Historic Landmark District.  The train offers scenic tours between the park and Williams, AZ.  Nearby stairs provide access to the Rim Trail and Verkamp’s Visitor Center (and the end of the Trail of Time).

 

Stop #5     Bright Angel Lodge.  This stop affords a plethora of lodging, shopping, and dining opportunities at El Tovar Hotel, Kachina Lodge, Bright Angel Lodge, Kolb Studio and Lookout Studio and lies a mere stone’s throw from the canyon rim.  Here, the Rim Trail is also the most congested location on the South Rim.

 

Stop #6     Hermits Rest Route Transfer.  From this stop, you can quickly walk to the Village Route Transfer of the red transit route and access the very scenic western end of the South Rim’s many viewpoints.  The Rim Trail also passes right by this location, and a short walk east brings you to the Bright Angel Trailhead.  The Bright Angel Trail is easily the most popular hiking trail in the park (see the Bright Angel, River, and Plateau Point Trails – Tr 1A.2 described in the Optional Hiking Trails section).  This trail is one of three “corridor” trails within the park’s vast trail system (the North and South Kaibab Trails being the other two), meaning that it is regularly patrolled by rangers and that it receives routine maintenance; but it also suffers from large crowds of day-hikers.  The upper portion of the trail follows break-down slopes along the Bright Angel fault at the head of Garden Creek canyon.  Its geological exposures, gentle, switch-backed gradient, piped-in water, and bathrooms make it ideal for a day-hike; adding an overnight stay at shady Indian Garden Campground and an evening stroll out to Plateau Point for a view of Granite Gorge makes it an unforgettable first-time backpacking experience (see the Bright Angel, River, and Plateau Point Trails – Tr 1A.2 described in the Optional Hiking Trails section).  Following the Bright Angel Trail all the way to the Colorado River provides access to the River Trail, which joins the Bright Angel to the South and North Kaibab Trails via a short hike up the south side of the river within Granite Gorge (see the Bright Angel, River, and Plateau Point Trails – Tr 1A.2 described in the Optional Hiking Trails section).

 

Stop #7     Maswik Lodge.  This location provides additional lodging, shopping, and dining options.

 

Stop #8     Backcountry Information Center.  If you plan to do any overnight hiking below the canyon’s rim, you’ll first need a backcountry permit which can only be obtained here.  The park service does reserve a few campsites below the rim for “walk-ins” at the information center, but because of the popularity of overnight trips, I highly recommend using the Grand Canyon National Park’s website which offers a means of obtaining permits well in advance of your intended backpacking trek.

 

Stop #9     Center Road.  An out-of-the-way location; but this stop does offer a small public parking area and access to the Greenway Trail.

 

Stop #10     Village East.  This location lies near the Train Depot stop (which can take you westbound again) and access to the same places described there; from here, you leave the Grand Canyon Village National Historic Landmark District heading eastbound.

 

Return to Stop #3     Refer to Map 1A.1.  Shrine of the Ages (Eastbound).  This stop returns you to the Shrine of the Ages and its recreational offerings.

 

Stop #11     Mather Campground.  If you enjoy car-camping, you’ll likely be staying in the park’s own Mather Campground with its wooded, relatively spacious, and secluded campsites (and convenient access to showers and laundry).  This stop offers ready eastbound access to the park visitor center where you can hop on an orange transit bus; however, if your goal is the main hub of activity in the Grand Canyon Village National Historic Landmark District, I would walk the extra distance to the Shrine of the Ages Westbound stop.

 

Stop #12     Trailer Village.  For the travel-trailer camper, the park offers more luxurious accommodations here; remain on the shuttle to the visitor center, or exit at Market Plaza Eastbound and catch the next available blue westbound bus.

 

Stop #13    Market Plaza Eastbound.  This stop returns you to Market Plaza (described earlier); remain on the shuttle to the visitor center, or exit here and catch the next available bus at the Westbound stop across the road.

 

Return to Stop #1     Grand Canyon National Park Visitor Center.  You have come full-circle.  From here, catch your choice of shuttles on the westbound blue, orange, or purple transit routes.

 

Orange (Kaibab/Rim) Route

The orange transit route affords access to Yaki, Mather, and Yavapai Points and their spectacular views across the widest stretch of the Grand Canyon to the North Rim’s Kaibab Plateau (Figure 1A.1).  The South Kaibab Trail and eastern terminus of the Rim/Greenway Trail system are equally worthy destinations reached from this shuttle route.

 

Stop #1     Refer to Map 1A.1.  The main shuttle terminal at the Grand Canyon National Park Visitor Center.  From this location, you can take the orange transit route east to the South Kaibab Trailhead, Yaki Point and Pipe Creek Vista, or west to Mather Point and Yavapai Point.  This description assumes that you head east first, then to the west.

 

Stop #2     South Kaibab Trailhead.  The main purpose of this stop is to deposit eager hikers at the trailhead for the South Kaibab Trail (see the South Kaibab Trail – Tr 1A.4 described in the Optional Hiking Trails section).  The South Kaibab Trail is one of three “corridor” trails within the park’s impressive system of trails (the Bright Angel and North Kaibab Trails being the other two), meaning that the trail is regularly patrolled by rangers and that it receives routine maintenance; but it also suffers from large crowds of day-hikers and the occasional mule train.  However, the trail is rather unique in that it follows an eye-popping, ridgeline descent for much of its length (unlike most of the park’s trails which are confined to canyons) and it offers spectacular scenery at every turn.  The view point from the top of the Redwall Limestone at the end of Cedar Ridge makes for an awesome day-hiking goal.  The South Kaibab Trail joins the North Kaibab Trail at river level, and merges with the Bright Angel Trail just down river via the connecting River Trail, a short hike along a stretch of Granite Gorge (see the Bright Angel, River, and Plateau Point Trails – Tr 1A.2 described in the Optional Hiking Trails section).

If you feel in the mood for walking, but would rather not endure the rigorous workout that all rim-to-river trails entail, the official beginning to the Rim Trail starts at the southwest edge of the parking area (Map 1A.1), allowing you to hike from here all the way to Hermits Rest should you so desire, a mere 12.3 miles to trail’s end.  It is approximately 1.0 mile between here and Pipe Creek Vista (Stop #4 on the orange transit route).  If you have children, a pleasant day-hiking option you might consider is a leisurely stroll from here to the Hermits Rest Route Transfer (Stop #6 of the blue transit route).  Roughly 4.5 miles in length, this hike affords great canyon views, and offers many rest stops, potty breaks, and educational opportunities along the way.

 

Stop #3     Yaki Point.  This scenic vista lies on a promontory at the head of Cedar Ridge which separates Cremation Canyon on the east from Pipe Creek Canyon on the west.  It is one of the South Rim’s premier viewpoints, and not to be missed.  This is also my unofficial trailhead for the Rim/Greenway Trail system.  With only gentle undulations, it offers relatively easy hiking, and its entire 13-mile length can be completed in a day (although with so many incredible vistas to suite any taste, I recommend splitting the trail into a two-day feast).  The “unofficial” beginning to the Rim Trail starts at the southwest edge of the parking area (Map 1A.1).  It is just over 0.5 miles to the South Kaibab Trailhead parking area from here.  Starting from this location adds relatively little to the nearly thirteen mile point to point trek from here to Hermits Rest, but in its doing, one can boost that they have truly seen all the South Rim has to offer.

If you plan an excursion to Yaki Point, be sure to include a sunrise in your itinerary, this one is a classic (Figure 1A.2).  In spring, the sun is seen to rise over flat, Kaibab Limestone-capped Wotans Throne, an isolated remnant of the North Rim’s Walhalla Plateau (the similarly capped pinnacle of Vishnu Temple rises just to the right).  A gorgeous sunrise-enhanced view into Pipe Creek Canyon and its western headwall comprised of the alternating cliff-slope-cliff-slope pattern of Paleozoic strata is worth every effort to catch the early shuttle (Figure 1A.3).  Here, as with every rimtop view, the upper sequence of rocks is comprised of the Kaibab Limestone, Toroweap Formation, Coconino Sandstone, Hermit Shale, and Esplanade Sandstone of the Supai Group.  The outcrop pattern of these formations is observed throughout the Grand Canyon and will become like an old familiar friend, a product of differential erosion of alternating hard and soft sedimentary rock layers.  In the Grand Canyon and southwest more generally, limestones and sandstones typically erode into resistant cliff-formers, while mudrocks such as shale erode into nonresistant slopes.

Figure 1A.2 Yaki Point Sunrise copyrighted

Figure 1A.2.  Sunrise over Wotans Throne and Vishnu Temple from Yaki Point; what place could paint a more iconic image of the Grand Canyon landscape?

 

Figure 1A.3 Kaibab Limestone and sunrise at Yaki Point copyrighted

Figure 1A.3.  The western wall of upper Pipe Creek Canyon as viewed from the west side of Yaki Point; note the alternating cliff-slope-cliff pattern of resistant Kaibab Limestone, soft mudrocks of the Toroweap Formation, and resistant Coconino Sandstone, a product of differential erosion.

 

Many of the Colorado River’s tributary canyons have been notched into the landscape along fault-controlled lineaments, and Cremation Canyon is no exception.  Cremation Creek carved its canyon along the northwest-southeast trending Cremation Fault (Figure 1A.4a); fracturing of the rocks having generated a ready-made zone of weakness exploited by stream erosion.  Careful observation of the valley floor reveals up-to-the-southwest displacement of rock layers associated with reverse movement on the Cremation Fault caused by crustal compression during the Late Cretaceous – Early Teritary Laramide Orogeny (Figure 1A.4b).  The Middle Cambrian Tapeats Sandstone is folded over and partially ruptured by the fault and red Hakatai Shale of the Late Proterozoic Grand Canyon Supergroup overlies the Tapeats on the west side of the fault.  Part of the South Kaibab Trail can also be observed from your vantage point where it passes around the east flank of O’Neill Butte and descends from Cedar Ridge through the Redwall and Muav Limestones (Figure 1A.5).  Follow the trail’s descent; the contact between the red Supai Group and gray Redwall Limestone occurs just before the notch at the end of Cedar Ridge, while the Redwall – Muav contact occurs at trail levelbelow the Redwall cliff, right at the break in slope.   Incidentally, the flat just before reaching the notch in the Redwall makes an excellent day-hiking destination if you want to obtain a much closer view of the Colorado River’s Granite Gorge; the occasional condor perched along the crest of Cedar Ridge makes for a worthy bonus.

Figure 1A.4 Fault-controlled Cremation Canyon copyrighted

Figure 1A.4.  Yaki Point affords an excellent view of fault-controlled Cremation Canyon (A), the arrow indicates the approximate position of the fault; Cremation Fault offsets Proterozoic and lower Paleozoic sedimentary rocks by up-to-the-southwest motion (B), where Late Proterozoic Hakatai Shale lies juxtaposed against the Tapeats Sandstone along the fault trace (indicated by the dashed line).

 

Figure 1A.5 South Kiabab Trail from Yaki Point copyrighted

Figure 1A.5.  A portion of the South Kaibab Trail can be seen from Yaki Point; it clings to O’Neill Butte’s eastern face and then crosses a flat stretch at the Redwall – Supai Group contact before descending through a notch in the Redwall Limestone at the end of Cedar Ridge, eventually passing into Muav Limestone near the base of the ridge.

 

Stop #4     Pipe Creek Vista.  Pipe Creek carved its canyon along faults subsidiary and subparallel to the northwest-southeast trending Cremation Fault.  The view here lies more or less along the axis of the canyon and it is not difficult to observe its linear shape, a product of fault-controlled erosion.  Below you, note the sharp V-notch at the head of Pipe Creek Canyon where water has exploited the fault trace to form sheer walls of Redwall Limestone.  As with many rim views, this is a good place to observe differential erosion by focusing your attention on the stair-stepped nature of the upper Paleozoic sequence (Figure 1A.6).  The cliff-bands of Kaibab Limestone, Coconino Sandstone, and Esplanade Sandstone of the Supai Group formed in response to their relatively high resistance to weathering and erosion, in contrast to the Toroweap Formation and Hermit Shale which are slope-formers, a consequence of their relatively weak mudstone composition.  The Coconino forms less of a distinctive cliff here compared to most locations because it has been highly fractured by faulting (compare this rim section to its counterpart on the west side of Pipe Creek Canyon).

Figure 1A.6 East Headwall of Pipe Creek Canyon copyrighted

Figure 1A.6.  Pipe Creek Canyon’s eastern headwall is adorned by a layer cake of Paleozoic sedimentary rocks whose alternating cliff-slope topography is a product of differential erosion, while in the distance, the Grand Canyon’s North Rim displays a similar banded pattern; look more closely at the nearby cliffs, you may notice that the Coconino appears crumbly, an expression of the “shattering” influence of the Cremation Fault.

 

Looking to the east headwall of Pipe Creek and beyond (Figure 1A.6), one can attempt to place some perspective on the vastness of the Grand Canyon.  A discerning eye can pick out the trace of the South Kaibab Trail as it first comes into view ascending ledgy outcrops of interbedded red Supai Group and Hermit Shale sandstones and mudstones along Cedar Ridge, then through the much-subdued, fault-shattered cliffs of Coconino Sandstone, and finally along a lengthy traverse through slopes of Toroweap Formation mudstones, eventually disappearing back into the recesses of the canyon where it will climb tight switchbacks in rapid succession up through the imposing banded cliffs of Kaibab Limestone.  And in the distance, across the inner gorge of the Colorado River, one can easily make out the thick white band of the Coconino Sandstone’s normally impressive cliffs along the Grand Canyon’s North Rim.

Other evidence of the erosive forces at work in the Grand Canyon is also on display within the confines of upper Pipe Creek Canyon.  Figure 1A.7 focuses your attention on two large blocks of Redwall Limestone that have become detached from the eastern headwall; blocks such as these are fairly common where a resistant rock unit like the Redwall overlies weaker rock units like the muddy Muav Limestone and the Bright Angel Shale below it.  Mudrocks are easily weathered and eroded, even in the relatively dry climate of the Grand Canyon region, and they tend to backwaste more rapidly than resistant limestones and sandstones.  Here, backwasting of the weaker Bright Angel Shale and overlying Muav Limestone (actually comprised of shale interbeds nearer its base with an increasing dominance of limestone upward) has destabilized the massive Redwall Limestone causing blocks to break lose and slide downward over the underlying mudrock slopes.

Figure 1A.7 Slump blocks in the Redwall Limestone, upper Pipe Creek Canyon copyrighted

Figure 1A.7.  Slump blocks formed in the Redwall Limestone cliffs of upper Pipe Creek Canyon; the normally dense, resistant Redwall has become unstable and fractured into large slabs that are gradually sliding downslope due to rapid weathering and erosion of the weaker Muav Limestone and Bright Angel Shale which lie below it.

 

From this location, you can rejoin the shuttle and eventually make your way to Mather Point; or you can hike or bike the 1.4 paved miles to Maher Point instead, enjoying wonderful views of Pipe Creek Canyon and Cedar Ridge enroute (Map 1A.1).

 

Return to Stop #1     Grand Canyon National Park Visitor Center (westbound).  Remain on the bus; since the orange transit route runs both east and west from the main shuttle terminal at the visitors center, one must return here briefly before heading to Mather Point (if you intend to take in both portions of the orange route).

 

Stop #5     Mather Point.  This wonderful vista is named for Stephen Mather, the first director of the National Park Service.  Few locations more splendid than this one could serve as a reminder of Mather’s contributions to conservation of our nation’s most uniquely spectacular places, both as an advocate for the creation of the National Park Service, and then as manager of the fledgling agency for its first dozen years of operation.  Because of its location nearest the south entrance to Grand Canyon National Park, as well as its proximity to the new park visitor center and its attendant parking lots, Mather Point tends to draw huge crowds.  However, the overlook is well chosen, offering scenic beauty, especially at sunrise or sunset, and wide-open views both up and down canyon, making it worth the amusement park feel; and I admit that I do take  pleasure in hearing those first gasps and exclamations of awe from many a canyon initiate here.

Mather Point is an ideal location to experience the oft-mentioned array of shifting colors and patterns comprised of rock and shadow as the sun advances through its day.  Dawn and dusk are especially pungent.  The up-canyon view of Wotans Throne and Vishnu Temple at sunset that is presented in Figure 1A.8, pretty though it may be, is a mere vestige of the true grandeur of this Grand Canyon phenomenon.  You really must experience it for yourself; the view down-canyon from Mather Point is equally enchanting, especially at sunrise (Figure 1A.9).  Standing at Mather Point, gazing into the canyon and basking in its immensity, a first experience for many, can elicit a multitude of responses; but surely nearly universal among them is an appreciation for the vastness of time.  Questions come to mind, such as how much time did it take to create all of those rock layers, and the Grand Canyon is so huge, how much time did it take to carve this landscape?

Figure 1A.8 Mather Point sunset, looking upcanyon copyrighted

Figure 1A.8.  Sunset on Wotans Throne and Vishnu Temple; viewed from Mather Point.

 

Figure 1A.9 Mather Point sunrise, looking downcanyon copyrighted

Figure 1A.9. A sunrise view down canyon from Mather Point; the interplay among colored rocks, light, and shadow in the Grand Canyon is unparalleled.

 

Returning to our geological roots, perhaps this is a good time to recall that the Grand Canyon exposes almost two billion years of earth’s history, including a thick Paleozoic sedimentary rock sequence, the Great Unconformity (in places representing as much as 1.2 billion years of missing rock), graben-filling Late Proterozoic sedimentary rocks of the Grand Canyon Supergroup, and Middle Proterozoic crystalline basement rocks of the Granite Gorge Metamorphic Suite (Figure 1.4), plus a multitude of faults and folds related to ancient and ongoing regional tectonic upheaval (Figure 1.3).  Most visitors peering into the Grand Canyon from Mather Point can readily distinguish the layer-cake arrangement of rocks within by their color, thickness, and stair-step-like exposure pattern.  In addition to their artfulness, Figure 1A.8 and 1A.9 display these patterns remarkably well.  Identifying faults and folds can be more challenging, but it is a good bet that most tributary canyons are dissected along the traces of ancient faults; and it is also likely that many of the isolated pinnacles and buttes within your field of view (and common throughout the canyon) are a product of the gradual erosion and wastage of larger mesas first separated from the main canyon rims along fault controlled weaknesses in the layer-cake of sedimentary rocks.  Vishnu Temple, Wotans Throne, and the Walhalla Plateau present a living example of the latter process (Figure 1A.8); Vishnu Temple, lying farthest to the south and closest to the canyon axis, was separated from the main North Rim for the longest time and is eroded to a mere pinnacle, while Wotans Throne separated more recently in time, forms a butte, with the main rim comprising Walhalla Plateau lies farthest the north and at the greatest distance from the canyon axis.

Mather Point lies on the east side of a major South Rim promontory separating the west trending Pipe Creek Canyon from the east trending Garden Canyon.  A pleasant 0.7 mile walk on the Rim Trail brimming with excellent views will take you to the end of the promontory at Yavapai Point (Map 1A.1).  Doubling that distance completes a short loop that takes you along the west side of the promontory for equally gorgeous down canyon vistas, where you can join a short 0.4 mile trail back to the Shrine of the Ages and a shuttle ride on the eastbound blue transit route back to the Grand Canyon Visitor Center near Mather Point.

 

Stop #6     Yavapai Point and Geology Museum.  Occupying a location at the head of the first bold promontory east of the main Grand Canyon Village area, and west of the park visitor center, combined with ease of accessibility by foot, private car, or transit bus, Yavapai Point is one of the most visited of the South Rim viewpoints.  The presence of a small museum specializing in Grand Canyon geology, plus the fantastic 180 degree panoramic view of the inner canyon and North Rim, make this site a must-see destination.  Unobstructed views up, down, and across the canyon are ideal for observing many of the geologic features common to the Grand Canyon.  One such view unfolds across the inner gorge of the Colorado River to the northwest where Trinity Canyon can be followed to its sources on the North Rim at Shiva Temple (Figure 1A.10).  Granite Gorge in the depths of the Colorado’s inner canyon snakes darkly across most of your panoramic view, its walls comprised of dense Middle Proterozoic crystalline basement, here mainly Vishnu Schist intruded by pinkish ribbons of Zoroaster Granite (Figure 1.4).  These rocks formed deep within the earth’s crust, grafted to the ancient North American continent at the site of collisional mountain building long ago.  Original sediments comprising the Vishnu are folded tightly into nearly vertical layers of metamorphic rock that was periodically intruded by felsic magma that would cool and solidify to form the Zoroaster.   The resistance of these crystalline rocks forces the Colorado River to expend much of its erosive energy on downcutting, there is little energy left over for meandering about, hence explaining the deep V-notch of the Grand Canyon’s inner gorge.

Figure 1A.10 Trinity Creek Canyon from Yavapai Point copyrighted

Figure 1A.10.  The inner gorge of the Colorado River and Trinity Creek Canyon from Yavapai Point; the tributary drainage is headed by Shiva Temple which is framed by the dual Coconino Sandstone-capped  spires of Isis Temple (on the right) and Osiris Temple (on the left).

 

The main portion of Trinity Canyon is confined by walls of sedimentary rock (Figure 1A.10).  The Tapeats Sandstone, oldest of the Paleozoic layer-cake of sedimentary rocks overlying the crystalline basement (Figure 1.4), forms a distinctive thick, horizontal, brown band capping the igneous and metamorphic rocks below.  The Tapeats rests on the Great Unconformity, the gently undulating surface generated by countless millennia of weathering and erosion that exhumed the core of ancient mountains.  The grayish slopes above the Tapeats are formed of Bright Angel Shale and Muav Limestone (Figure 1.4), the threesome of rock units completing a fining-upward sequence of sedimentary rock generated by worldwide Middle Cambrian marine transgression.  Above the gray slopes of Bright Angel and Muav lay the massive red cliffs of resistant Mississippian Redwall Limestone (Figure 1.4), its natural gray marine carbonates coated in red muds derived from oxidized sediments carried down from above.  Resting on the Redwall is the distinctively red, stair-stepped bands of the Pennsylvanian and lower Permian Supai Group and Hermit Shale (Figure 1.4), the source of the Redwall’s adobe texturing.  These units are partially terrestrial, deposited along an arid coastline undergoing periodic marine incursions.  To complete the picture, follow Trinity Creek upward, its dual arms encircle Shiva Temple, a large butte capped by resistant Permian Kaibab Limestone isolated from the main Kaibab rim beyond.  Trinity Canyon and Shiva Temple are framed by the twin pinnacles of Isis Temple to the east and Osiris Temple to the west, both erosional remnants topped by resistant Permian Coconino Sandstone.  The Permian Toroweap Formation forms the vegetated, slope-forming unit between the whitish cliffs of Coconino and Kaibab (Figure 1.4).  The Coconino formed in a huge coastal desert, while the successive layers of the Toroweap and Kaibab represent a gradual return to marine conditions.

Aside from the wonderful exhibits housed in Yavapai Point’s Geology Museum, this stop offers another educational opportunity that should not be overlooked.  Following the Rim Trail west of the Geology Museum toward the main village area (Map 1A.1), one can gain immediate access to the Trail of Time.  Completed in 2010, this stretch of the Rim Trail has been marked off in one-meter-per-million-year increments that provides a unique, distance-equals-time comparative view of the passage of time exposed in the walls of the Grand Canyon.  Walking west from the museum and into the earth’s past, each geological rock unit that has been described and mapped in the Grand Canyon is laid out in its proper place along the trail by its inferred age (Figure 1A.11).  The Trail of Time occupies about 2.1 km of the Rim Trail and covers about 2.1 billion years, the entirety of the rock record unearthed by canyon carving.

 

Figure 1A.11 Trail of Time, Yavapai Point to Ver Camp's Visitor Center, South Rim copyrighted

Figure 1A.11.  The pedestal of Elves Chasm Gneiss marks the beginning of the Trail of Time just west of Yavapai Point; this section of the Rim Trail is marked off in one-meter-per-million-year increments with each rock unit exposed by canyon dissection laid out in its proper place along the trail by its inferred age, and offering a uniquely visual display of the immensity of time portrayed within Grand Canyon’s depths.

 

Regardless of your reasons, a walk along the South Rim west of Yavapai Point offers world premiere geology.  From here to the Hermits Rest Route Transfer is a 1.9 mile stroll; if it is all the time you’ve got, it may just be the hike that you don’t want to miss (Map 1A.1 and Map 1A.2).  A definite highlight on this stretch of trail is the little publicized overlook well deserving of its name, Grandeur Point.  Situated at the end of Garden Canyon’s eastern rim, Grandeur Point offers stunning vistas, from its intimate view deep into the confines of Garden Creek’s canyon, to its broad views of the main Colorado River canyon, Bright Angel Canyon, and the North Rim beyond.  Along the western side of the promontory and nearly opposite your vantage point, the panorama provides an unparalleled view of the straight-as-an-arrow confines of Bright Angel Canyon where its perennially flowing creek has cut a deep trench back into the North Rim west of Walhalla Plateau (Figure 1A.12).  The distinctive lineament of this large tributary canyon is matched on the South Rim by Garden Canyon.  This unique lineation is controlled by the Bright Angel Fault, canyon erosion having occupied the path of least resistance as streams tributary to the Colorado River cut downward, keeping pace with base level lowering.  The Bright Angel Fault first formed in the Late Proterozoic as a normal fault generated by extensional tectonics during the breakup of the supercontinent of Rodinia, but was subsequently reactivated as a reverse fault during the Late Cretaceous – Early Tertiary compressional tectonic regime associated with the Laramide Orogeny.  And this major rupture is probably at it again, recently reactivated as a normal fault during ongoing Basin and Range extension.  Figure 1.3 shows many other faults in the region with similarly complex histories; the take-away here is that old faults never die, they just quiet down from time to time.

Figure 1A.12 Bright Angel Canyon from Granduer Point on the South Rim copyrighted

Figure 1A.12.  Bright Angel Canyon from Yavapai Point; the distinctive linearity of this large tributary to the Colorado is the result of preferential stream erosion along the trace of the Bright Angel Fault, a Late Proterozoic normal formed by extensional tectonics and reactivated as a reverse fault during the Late Cretaceous – Early Tertiary Laramide Orogeny and again as a normal fault during ongoing Basin and Range extension.

 

East of Grandeur Point, turn your gaze toward Garden Canyon’s headwall which offers a superb view of the up-to-the-west displacement of sedimentary rocks related to Laramide movement on the Bright Angel Fault (Figure 1A.13).  As you examine the headwall area, look for evidence of faulting.  For starters, trace the path of the Bright Angel Trail downward from the rim; most rim-to-river trails were developed along breakdown slopes in the Paleozoic strata, and this one is no exception.  Faults such as the Bright Angel generally rupture along multiple, closely spaced, subparallel fractures called a fault zone, and only rarely occur along a singular plane; that rupturing produces countless small breaks in the rock layers, weaknesses exploited by weathering and erosion that results in copious amounts on talus, hence the breakdown slopes.  Notice also that the Kaibab Limestone caprock of the South Rim is not level; buildings of Grand Canyon Village occupy a segment of the South Rim that lies below Garden Canyon’s western wall; the dip at the back end of Garden Canyon indicates fault displacement.  Finally, follow any layer of sedimentary rock west to east through the very head of the canyon, the Coconino Sandstone’s massive, buff-colored cliff is one such a standout, and you can see that that layer is displaced downward on the nearer, eastern, Grand Canyon Village side (or upward on the western side).

Figure 1A.13 Bright Angel Fault from Grandeur Point copyrighted

Figure 1A.13.  The headwall of Garden Canyon is split by the Bright Angel Fault (dashed line); the readily visible displacement of Paleozoic sedimentary rocks was generated by up-to-the-west motion related to Laramide age compression (although the fault is currently undergoing extension).

 

Return to Stop #1     Back to the Grand Canyon National Park Visitor Center.  Your tour of the orange transit route is complete.  From the main shuttle terminal you can catch connecting buses for either the westbound blue or purple transit routes.

 

Red (Hermits Rest) Route

The red transit route takes you to the wide open spaces west of the Grand Canyon Village, with access to the alluring views at Maricopa, Powell, Hopi, Mohave, and Pima Points, as well as the historically significant Hermits Rest (Figure 1A.1).  The Hermit Trail and western portion of the Rim/Greenway Trail system are also afforded from this shuttle route.

 

Stop #1     Refer to Map 1A.2.  Village Route Transfer.  The red transit route provides access to many of the South Rim’s classic viewpoints along the old West Rim Drive.  Begin your tour from here; I recommend an early departure if you want to avoid the crowds and are planning to hike portions of the Rim Trail along the way.  Walking from here to Maricopa Point to catch the shuttle is one of my favorite geological strolls in the park.  Alternatively, the paved road and Greenway offer a great low-traffic volume biking opportunity.

 

Stop #2     Trailview Overlook.  Looking back to the southeast form this viewpoint, the Grand Canyon Village Historic District can be seen lying in a natural depression along the South Rim at the head of Garden Canyon (Figure 1A.14a).  The dip in the rim here is related to down-to-the-east displacement on the Bright Angel Fault, as well as preferential weathering and erosion caused by fault-induced weaknesses in the cap rock.  The view is difficult at this angle, but a discerning eye may notice that the Coconino Sandstone on this side of the fault is higher than on the southeast side.  The village was established at the end of the Grand Canyon Railway (formerly a spur line of the Santa Fe Railroad) and the major cross-canyon hiking route comprised of the Bright Angel and North Kaibab Trails.  Now follow the Bright Angel Trail as it zigzags down through the Paleozoic rock formations in upper Garden Canyon (Figure 1A.14b).  The trail briefly crosses onto the Bright Angel Fault near the contact between the slope-forming Toroweap Formation and the cliff-forming Coconino Sandstone, and then makes a series of tight switchbacks on a colluvial wedge of Toroweap debris deposited along the fault where it has completely fractured and offset the Coconino.  The trail passes through the Coconino cliffs at a fault-related breakdown slope, a common feature of Grand Canyon rim-to-river trails.

Figure 1A.14 Grand Canyon Village and Bright Angel Fault from Trailview Overlook

Figure 1A.14.  Trailview Overlook offers a good opportunity to observe evidence of faulting; (A) Grand Canyon Village Historic District lies at the head of Garden Canyon in a natural depression along the South Rim related to down-to-the-east displacement on the Bright Angel Fault; (B) the Bright Angel Trail zigzags down from the rim, crossing onto the fault near the contact between the Toroweap Formation and Coconino Sandstone, then makes a series of tight switchbacks on a colluvial wedge of Toroweap debris deposited along the fault trace where it has completely fractured and offset the Coconino.

 

Stop #3     Maricopa Point.  This viewpoint lies on the east side of the multipronged promontory projecting well out into the main canyon just west of Grand Canyon Village.  The point overlooks Horn Creek Canyon bordered by ridges of Supai Group and Redwall Limestone forming The Battleship on the right and a long buttress extending to Dana Butte on the left (Figure 1A.15); its panoramic view spreads along the North Rim from northeast of Bright Angel Canyon to northwest of Trinity Canyon and Shiva Temple.  Maricopa Point offers the best opportunity to view sedimentary rocks belonging to the Late Proterozoic Grand Canyon Super Group in this part of the Grand Canyon, although rocks of the Paleozoic sedimentary sequence above as well as the Middle Proterozoic Grand Canyon Metamorphic Suite below are also superbly on display.  Starting with the narrow inner gorge nearest the river, dark rocks seemingly shot through with lightly-colored ribbons comprise the crystalline basement made up of vertically foliated Vishnu Schist intruded by the Zoroaster Granite (Figure 1A.15). The multihued layers of flat-lying, more brightly-colored rocks stacked above form the Paleozoic sedimentary rocks so prominent throughout the canyon.  The contact between these major rock bodies is fairly obvious, a nonconformity known as the Great Unconformity, readily identified where the buff-colored Tapeats Sandstone rests on the igneous and metamorphic crystalline rocks at the lip of the inner gorge.

Figure 1A.15 Bright Angel and Trinity Canyons from Maricopa Point copyrighted

Figure 1A.15.  Two views from Maricopa Point; (A) shows the right-hand side of Horn Creek Canyon and its eastern bounding ridge forming the The Battleship in the foreground, with Bright Angel Canyon’s linear, fault-controlled trench descending from the North Rim in the background, (B) shows the left-hand side of Horn Creek Canyon and its western bounding ridge ending in Dana Butte in the foreground, with Trinity Canyon headed by Shiva Temple loaming large in the background.

 

Not all of the rocks in your field of view comprise Paleozoic sediments.  A prominently paired cliff and slope of red sandstone and shale are exposed at the base of Cheops Pyramid, running from Bright Angel Canyon (Figure 1A.15a) southward to near the position of Isis Temple (Figure 1A.15b).  These distinctive rock layers are the Shinomo Sandstone and Hakatai Shale, Mesoproterozoic sedimentary rocks of the lower Grand Canyon Supergroup (the red rock cliffs below the pyramid are often mistaken as Tapeats Sandstone, but are instead Shinomo Sandstone).  Difficult to discern from this rim view, the Supergroup rocks dip to the northeast within a large fault-bounded graben formed during crustal extension associated with Neoproterozoic rifting of the Rodinian supercontinent.  The Shinomo Sandstone would have formed a resistant, ridge-like “island” during Middle Cambrian marine transgression that was not immediately inundated, consistent with the lack of Tapeats Sandstone over the tilted red cliffs here which are instead overlain by the Bright Angel Shale.  Figure 1A.16 focuses attention on the area just below and to the fore of Cheops Pyramid.  The NW-SE trending normal fault bounding the southwest side of the aforementioned graben is exposed at either end of a table-like feature formed of Tapeats Sandstone in the center of the photograph (and passes beneath the “table” as well).  Within the graben, Shinomo and Hakatai units dip away to the northeast, while crystalline basement is exposed on the southwest upthrown side of the fault.  The Tapeats Sandstone capping crystalline basement at the lip of Granite Gorge in this view thins away from the gorge, pinching out against the Shinomo Sandstone cliff, especially below the pyramid.

Figure 1A.16 Granite Gorge from Maricopa Point copyrighted

Figure 1A.16.  The inner gorge of the Colorado River, known as Granite Gorge, exposes Middle Proterozoic crystalline basement comprised of the dark-colored, vertically foliated Vishnu Schist intruded by stringers of pinkish-colored Zoroaster Granite.

 

If you feel in the mood to stretch your legs a bit, this stop provides access to a wonderful little 1.6 mile segment of the Rim Trail covering Maricopa, Powell, and Hopi Points.  All three locations occur at nearly the same elevation, so the hike is an easy saunter for families with young children, and the views offer nearly the full gambit of what the South Rim has to offer in terms of scenery and geology.

 

Stop #4     Powell Point.  This stop hosts a memorial to John Wesley Powell, the leader of the first two scientific expeditions through the Grand Canyon in 1869 and 1872, who later became the first director of the U.S. Geological Survey.  The viewpoint occupies a needle-like promontory that projects outward from the rim into upper Horn Creek Canyon.  Views here are very similar to Maricopa Point a short distance to the east.  A short hike between here and Mohave Point makes for an excellent introduction to Grand Canyon Geology and wonderful opportunities to catch a sunrise or sunset.

 

Stop #5     Hopi Point.  This overlook is perched at the rim’s edge on the middle toe of the multipronged promontory jutting out into the canyon just west of Grand Canyon Village due south of Dana Butte and the ridge separating Horn Creek Canyon on the east from Salt Creek Canyon on the west. The viewpoint lies almost directly opposite and closest to the twin spires of Osiris and Isis Temples north of the river, standing as sentinels to Shiva Temple herself at the head of Trinity Canyon (Figure 1A.17).  Both pinnacles are capped by white Coconino Sandstone, but Shiva Temple retains her crown of Kaibab Limestone.  The large, flat-topped temple is isolated from the North Rim by erosion along the Phantom Fault which trends northwest-southeast behind the edifice and then down Phantom Canyon.  The Cambrian Tapeats Sandstone forms a particularly prominent layer blanketing the much darker Middle Proterozoic Vishnu Schist above the Great Unconformity; this sandstone unit and all of the formations above comprise the Grand Canyon’s incomparable Paleozoic sedimentary rock sequence.

Figure 1A.17 Cross-canyon view of Shiva Temple from Hopi Point copyrighted

Figure 1A.17.  Hopi Point sits directly above the ridge hosting Dana Butte separating the Horn Creek and Salt Creek amphitheaters; the view due north from Hopi Point looks directly across the canyon to Osiris and Isis Temples which form gate posts bordering Trinity Canyon, with Shiva Temple in between.

 

This is an excellent place to consider the Grand Canyon’s Paleozoic stratigraphy.  Ubiquitous throughout the canyon is the prominent “bathtub ring” created by the white cliffs of the Coconino Sandstone (Figure 1A.17).  Using this rock unit as a guide, it is not difficult to pick out much of the stratigraphic sequence described back in the introduction (Figure 1.4).  The cliff-slope pair capping the rim and overlying the Coconino Sandstone is the Kaibab Limestone and Toroweap Formation, and directly beneath the Coconino cliff is a red sloping unit, the Hermit Formation; this foursome creates the stair-stepped upper rim of the canyon visible from anywhere.  Beneath the Hermit is the thick band of red ledgy slopes making up the Supai Group, four rock formations consisting of varying thicknesses of oxidized  sandstone and mudrock.  Below the Supai Group lies the major cliff-forming Redwall Limestone, typically scalloped into large curving alcoves separated by long narrow spurs (much like the ridge that connects Dana Butte to the South Rim directly below you).  The greenish, gray-yellow slopes consistently found below the Redwall form the broad expanse of the Tonto Platform which is well expressed here; these slopes are eroded from the Muav Limestone and Bright Angel Shale.  Another prominent cliff-band forms the final Paleozoic unit, the Tapeats Sandstone.

Take your time here, and be sure to explore all that Hopi Point has to offer.  A walk from its eastern end to its western end offers a nearly 180 degree panorama up, across, and down the main canyon.  At its western end, you are treated with the first view of the Colorado River on the red transit route, not to mention a particularly gorgeous vantage point (Figure 1A.18) and one of the most highly photographed sunset locations in the park.

Figure 1A.18 Down-canyon view from western end of Hopi Point copyrighted

Figure 1A.18.  A down-canyon view from the western end of Hopi Point, come back and enjoy the show at sunset, Hollywood could never do it better!

 

Stop #6     Mohave Point.  Lying on the westernmost protrusion of the three-toed promontory west of Grand Canyon Village, Mohave Point’s better than 180 degree panoramic view down canyon offers one of the most spectacular of the South Rim vistas (Figure 1A.19).  The overlook affords a bird’s eye view into the depths of Monument Canyon; a careful observer can even identify the canyon’s namesake, The Monument, a spire of Zoroaster Granite at the confluence of the main stream channel and its largest western tributary.  The usual suspects are all on eminent display as well, with a impressive view into the canyon’s inner gorge and its exposure of crystalline basement, as well as the many layered and multihued soaring cliffs and ramparts comprised of Paleozoic sedimentary rocks.  Down canyon, you are teased by excellent views of the Colorado River on your tour along the old West Rim Drive.  A close observation of the river corridor reveals two rapids, Granite at the mouth of Monument Creek, and Hermit at the mouth of Hermit Creek (Figure 1A.20a).  Notice that occurrence of both rapids seems to be tied with the confluence of the Colorado River and a major tributary canyon; this is no coincidence.  The turbulent, frothy flow of water through a rapids corresponds to a significant change in stream gradient, in this case a byproduct of the deluge of coarse, rocky debris delivered to the river by periodic flash flooding on its tributaries.  The Colorado’s energy would quickly remove these obstacles without renewed input of bouldery material by repeated flood events, probably reoccurring with a frequency of about one in every 50 years.

Figure 1A.19 Down-canyon from Mohave Point copyrighted

Figure 1A.19.  The down-canyon view from Mohave Point offers up deeply carved Monument Canyon, your first good opportunity to see the rushing waters of the Colorado River, and an excellent display of rock deformation, Grand Canyon style.

 

Faults and folds are also on display here.  Lying immediately before you is Monument Canyon (Figure 1A.19), its lower end at least in part controlled by erosion along the northwest – southeast trending Monument Fault.  More distantly, follow the Colorado River’s course downstream where it begins a gentle turn to the northwest, a prominent buttress of Redwall Limestone north of the river projects southward toward the inner gorge, paralleled on its eastern side by an obviously quite linear canyon.  This stone rampart-canyon pair is featured in the foreground of Figure 1A.20b; the ridge is capped by red Supai Group rocks comprising the Tower of Ra at its northern end.  The linearity of this natural rock wall, as well as the adjoining canyon to the fore, are telltale signs of fault-controlled rock deformation and stream erosion.  The trend of the buttress and canyon lie parallel to the trace of the Crystal Fault which cuts diagonally from north to south across the upper end of the ridge (just east of the Tower of Ra) from Crystal Canyon to Ninetyfour Mile Canyon through crystalline basement as well as Paleozoic rocks (Figure 1A.20b).  Looking further afield, shift your attention to the North Rim and the skyline (Figure 1A.19).  Just below the rim, the Coconino Sandstone forms its typical, horizontal white cliff-band.  Follow this layer from right to left to the first large V-shaped notch in the rim; this is the Muav Saddle, separating Powell Plateau from the North Rim proper.  As you have learned elsewhere, this notch too is a subtle sign of erosion along a fault, the Muav Fault in this case.  The Muav Fault was first active as a normal fault, generated by the regional extension that prevailed during breakup of the supercontinent of Rodinia in the Late Proterozoic.  As with a great many faults in the Grand Canyon region, more recently, the Muav Fault was reactivated as a reverse fault during the Late Cretaceous – Early Teritary compressional tectonics of the Laramide Orogeny.  Evidence of this latter stage of faulting is also exhibited in your view and best observed in Figure 1A.20b.  Notice that the Coconino  cliff-band to the left of the Muav Saddle bends downward as it approaches the notch; the red layers of Supai Group rocks beneath also bend downward toward the saddle.  The crustal block on which Powell Plateau was uplifted during Laramide compression, and the Paleozoic rocks that had accumulated on earlier faulted crystalline basement were fractured and warped into a monoclinal fold over the fault when it was reactivated between 75-50 million years ago.

Figure 1A.20 Monument Canyon from Pima Point

Figure 1A.20.  Views from Mohave Point; (A) the inner gorge and Hermit Rapids at the mouth of Hermit Creek, and (B) fault-controlled erosion in the form of Ninetyfour Mile Canyon (in the foreground) which is cut along the Crystal Fault and the V-notched Muav Saddle (along the skyline), and expression of the Muav Fault.

 

Mohave Point is an excellent location to get off the shuttle and hike a section of the Rim Trail.  You can easily reboard at either of the next two stops along the red transit route.  This stop perches at the northern end of the Great Mohave Wall, a particularly steep section of the upper Paleozoic sedimentary rock sequence forming the eastern side of Monument Canyon.  The steep headwall of Monument Canyon can be attributed to westward thickening of resistant, cliff-forming units in the Paleozoic sequence, especially the Redwall Limestone.  As you approach the next shuttle stop (Map 1A.2), look for tell-tale signs of rock falls from the Coconino Sandstone cliff along the canyon headwall (Figure 1A.21).  These features appear as fresh scars where unweathered sandstone is now exposed on the cliff face, accompanied by a downslope runner of bouldery scree, evidence that weathering and erosion is alive and well in the Grand Canyon.

Figure 1A.21 Rock falls along the Monument Canyon headwall near The Abyss copyrighted

Figure 1A.21.  Recent rockfalls at the head of Monument Canyon attest to active processes of weathering and erosion that have gradually sculpted much of the scenery arrayed before you.

 

Stop #7     The Abyss.  A brief stop here is worth it just for the sheer adrenaline rush of looking over the edge of the rim into Monument Canyon.  The canyon forms a deeply carved reentrant into the South Rim, bounded by incredibly high, steep cliffs that drop some 3000 feet to the base of the Redwall Limestone.  Let your eyes wonder out to Mohave Point and be sure to gape appropriately at the Great Mohave Wall that soars skyward along the eastern and most sheer side of the canyon.

 

Stop #8     Monument Creek Vista.  This stop offers another worthy look into Monument Creek’s depths.  It is also a great place to disembark from the shuttle and bike or hike on the newly paved Rim/Greenway Trail out to Pima Point, about 1.7 miles distant.  Choosing the trail potion, in about three quarters of a mile, you will pass an unnamed promontory overlooking Monument Canyon’s western side (Map 1A.3).  A viewpoint here affords a superb view of the lower canyon and confluence with the Colorado River (Figure 1A.22).  Granite Rapids occurs here; notice that once again, a rapids has formed at the mouth of a major tributary stream where loss of energy has forced the deposition of many a flash flood’s bouldery sediment load.

Figure 1A.22 Lower Monument Canyon from Rim Trail east of Pima Point copyrighted

Figure 1A.22.  Lower Monument Canyon and Granite Rapids observed from the unnamed promontory on Monument Canyon’s west side; the promontory viewpoint can be reached by following the Rim Trail west from the Monument Creek Vista stop on the red transit route.

 

Stop #9     Refer to Map 1A.3.  Pima Point.  This viewpoint lies at the end of a major promontory between Monument Canyon’s deep cleft, and Hermit Canyon’s wider, but more deeply inset drainage, and may just offer the most spectacular view along the West Rim Drive.  Lying at the promontory’s western edge, your eagle’s eerie provides a near perfect view of Hermit Creek’s expansive canyon (Figure 1A.23a).  Hermit Creek carved its canyon parallel to and on the downthrown western side of the northeast – southwest trending Hermit Creek Fault.  Several minor fault splays lie subparallel to the main fault and can be observed to cut through Supai Group and Redwall Limestone directly below your perch (Figure 1A.23b).  Weaknesses induced by the faultinghave caused slumping to occur within the Supai and Redwall units and resulted in a large landslide observed in Figure 1A.23b (the toe of the slide mass is brightly light by sunshine).  Much of lower Hermit Canyon is comprised of greenish-gray slopes eroded from the Muav Limestone and Bright Angel Shale and form the broad expanse of the Tonto Platform which is well expressed here (Figure 1A.23).  The thick, brown cliff-band underlying the platform comprises the Tapeats Sandstone, the final sedimentary rock unit of the Paleozoic sequence.  These latter three formations accumulated successively, during an overall rise in sea level during the Cambrian.  As the west coast of North America was inundated by marine transgression, sandy to pebbly Tapeats beaches were laid down in wave-agitated water, followed by deeper, quieter offshore waters that allowed accumulation of Bright Angel muds, and finally, the limestones of the Muav were formed on a distal carbonate platform far from terrigenous input.  The Tapeats rests on the undulating surface of the Great Unconformity; Middle Proterozoic Vishnu Schist and Zoroaster Granite lie below, so the erosional gap here represents nearly 1.2 billion years of missing rock record.

Figure 1A.23 Hermit Canyon from Pima Point

Figure 1A.23.  Your downcanyon panorama from Pima Point looks directly into the wide expanse of Hermit Canyon and on down the winding corridor of the Colorado River (A); Hermit Canyon is carved along the northeast – southwest trending Hermit Creek Fault, one splay of which can be observed to bisect the narrow ridge of Redwall Limestone forming Copeland Butte and pass into Supai Group rocks nearly under your feet (B).

 

If you have an opportunity, don’t miss the chance to witness a sunset from Pima Point (Figure 1A.24).  Perhaps not quite as outrageous (or well known) as that of a Mather Point sunset, but the downcanyon view is less obstructed and uniquely gorgeous.

Figure 1A.24 Sunset at Pima Point copyrighted

Figure 1A.24.  A marvelous sunset from Pima Point looking north along Copeland Butte, the narrow spine of Redwall Limestone separating Monument Canyon to the north from Hermit Canyon to the south; in the distance, the last rays of the sun shine on Shiva Temple, bounded to the east and west by Isis and Osiris Temples.

 

Stop #10     Hermits Rest.  The end of the line for the red transit route and the West Rim Drive; there is naught else to do but hike, bike, or ride the bus back to the first stop at the Village Route Transfer Station.  The views from Hermits Rest are not much to describe in comparison to what you’ve witnessed on the way here; but Hermits Rest is historically significant and it does offer a snack bar and gift shop.  This location serves as the jump off point for the Hermit Trail (see the Hermit Trail – Tr 1A.3 described in the Optional Hiking Trails section).  This is a classic rim to river trail which connects with the Boucher Trail and Dripping Springs Trail (see the Boucher and Dripping Springs Trails – Tr 1A.1 described in the Optional Hiking Trails section) in upper Hermit Canyon, as well as the Tonto Trail in the lower canyon (see the Tonto Trail West; Indian Garden to Boucher Creek – Tr 1A.5).  A long, but fairly popular day-hiking option is an out and back excursion to Dripping Springs, lots of great scenery and a great introduction to the Paleozoic geology of the inner canyon.  This location also serves as the end of the Rim/Greenway Trail and walk back to Pima Point and beyond is also a worthy goal from here.

 

Return to Stop #9    Pima Point.  The red transit route stops at only three locations on the return trip, the first is here at Pima Point.  An inviting option to your return ride is to hike the Rim Trail/Greenway Trail from here to Mohave Point around the lip of Monument Creek yawning amphitheater.

 

Return to Stop #6    Refer to Map 1A.2.  Mohave Point.  Second stop on the return route and a good opportunity for a pick up after you have hiked part of the Rim Trail/Greenway Trail from either direction.

 

Return to Stop #4    Powell Point.  The final stop on the return route.  A short hike between here and Grand Canyon Village in either direction makes a wonderful sunrise or sunset stroll.

 

Return to Stop #1    Village Route Transfer.  Back to the beginning of the red transit route; hope you enjoyed the show!  From this location, you can catch a connecting blue eastbound transit bus by walking over to the nearby Hermit Route Transfer Station.

 

Road Route and Hiking Maps

Phantom Ranch, AZ (WC quarter) (Map 1A.1)

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

 

Grand Canyon, AZ (EC quarter) (Map 1A.2)

Map 1A.2.  Shaded-relief map of the east-central quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

 

Grand Canyon, AZ (WC quarter) (Map 1A.3)

Map 1A.3.  Shaded-relief map of the west-central quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

 

Optional Hiking Trails for Field Trip 1A

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)

Please be patient; this section is under construction!

Hiking Trail Maps

grand-canyon-az-nw-quarter-map-1a-3-1

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. The complex geology at the confluence of Bright Angel Canyon and Upper Granite Gorge copyrighted

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.  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 granitic rock of the Pipe Creek Pluton is overhung by more resistant quartz sandstone of the Tapeats.  In several hundred feet, 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.2.18).  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.2.19).  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.2.18.  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.2.19.  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.2.20).

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

Figure 1A.2.20.  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.2.21).  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.2.22 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.2.21.  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.2.22.  A pothole drilled into an outcrop of Vishnu Schist by the swirling, sediment-laden flood waters of the Colorado River at Pipe Creek beach, my former student for scale.

 

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.2.23).  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.2.24).  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.2.24, with the greatest offset on the fault furthest down river.

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

Figure 1A.2.23.  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.2.24.  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.2.25), 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.2.25.  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.2.26).  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.2.27).  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.2.26.  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.2.27.  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

grand-canyon-az-ne-quarter-map-1a-2-1

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

 

phantom-ranch-az-nw-quarter-map-1a-2-2-and-1a-4-2

 

 

 

 

 

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.

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

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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.

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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.

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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.

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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).

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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).

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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.

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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).

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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.

figure-1a-3-13-faulted-supai-group-and-redwall-limestone-near-breezy-point-copyrighted

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.

figure-1a-3-14-fault-contact-between-the-supai-and-redwall-at-breezy-point-copyright

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).

figure-1a-3-15-top-of-the-cathedral-stairs-copyrighted

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.

figure-1a-3-16-fault-shattered-redwall-limestone-on-the-catherdral-stairs-copyright

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).

figure-1a-3-17-lower-cathedral-stairs-below-cope-butte-copyright

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

grand-canyon-az-nw-quarter-map-1a-3-1

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.

phantom-ranch-az-nw-quarter-map-1a-2-2-and-1a-4-2

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

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

Please be patient; this section is under construction!

Hiking Trail Maps

grand-canyon-az-nw-quarter-map-1a-3-1

Map 1A.5a.1.  Shaded-relief map of the northwest quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

 

Tonto Trail (Bright Angel Trail Junction to South Kaibab Trail Junction) (Tr1A.5b)

Please be patient; this section is under construction!

Hiking Trail Maps

phantom-ranch-az-nw-quarter-map-1a-2-2-and-1a-4-2

Map 1A.5b.1.  Shaded-relief map of the northwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.

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

Please be patient; this section is under construction!

Hiking Trail Maps

grand-canyon-az-nw-quarter-map-1a-3-1

Map 1A.5c.1.  Shaded-relief map of the northwest quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

grand-canyon-az-ne-quarter-map-1a-2-1

Map 1A.5c.2.  Shaded-relief map of the northeast quarter of the Grand Canyon, AZ 7.5 minute quadrangle.

phantom-ranch-az-nw-quarter-map-1a-2-2-and-1a-4-2

Map 1A.5c.3.  Shaded-relief map of the northwest quarter of the Phantom Ranch, AZ 7.5 minute quadrangle.