If you are seeking escape from the traditional, crowded overlooks of the North Rim, you might consider the Kaibab Plateau’s East Rim.  Easily accessed on a day-trip from your comfortable campsite at North Rim Campground, this field trip route highlights several viewpoints emphasizing the East Kaibab Monocline while driving backcountry roads in Kaibab National Forest (Figure 2.1). The roads are gravel surfaced and offer a solid tread for all vehicles, the trails are short and sweet, and there are even places to camp if you’d like to stay awhile in comparative solitude.  The East Kaibab Monocline formed by uplift and deformation 80-40 million years ago during the Laramide Orogeny that resulted from the upwarping of the Kaibab Plateau.  Both the East Rim and Marble Viewpoints provide superb views of the monoclinally-folded Paleozoic sedimentary rock sequence, that feel almost close enough to touch, while the Saddle Mountain Viewpoint offers a different perspective on the classic view into Nankoweap Canyon from Point Imperial and serves as a primary trailhead for the Nankoweap Trail.   Come and enjoy the beautiful drive through conifer forest, the breathtaking views, and a brief contemplation of the geological forces that caused upwarping of the Kaibab Plateau in the past for your pleasure today.

 

Route Description

0.0 (0.0)     Refer to Map 2B.1.  Return to the four-way intersection of AZ Hwy 67, FS Rd 22, and FS Rd 611.  The intersection is centrally located in De Motte Park, an elongated grassland surrounded by conifer forests and a former oasis for ranching.  Deer Lake, now fenced in to keep grazing cattle out, forms an almost perfectly circular lake occupying a sinkhole at the northwest quadrant of the intersection.  De Motte Park occupies the edge of a crustal slab dropped downward to the east along the De Motte Fault and the high ground to the right-hand (east) side of the meadow forms a fault scarp on the uplifted block.  Turn right (east) from AZ Hwy 67 onto FS Rd 611.

 

1.3 (1.3)     Refer to Map 2B.2.  FS Rd 611 quickly turns south and climbs to the top of the fault scarp and to an “X”-shaped four-way intersection with FS Rd 610.  Continue straight (east) on FS Rd 611.

 

4.1 (2.8)     The parking area for the East Rim Viewpoint lies on the right-hand can hike (east) side of the road here.  Turn in and park; it’s a short walk to the rim, although you can enjoy a stroll along the rim in either direction for more views.

 

The East Rim Viewpoint affords an intimate view of the East Kaibab Monocline and its constituent folded Paleozoic sedimentary rocks (Figure 2B.1).  The erosion caused by North Canyon has dissected deeply into the east-facing limb of the fold, but not entirely through the fold structure as it has further south in Nankoweap Canyon, so only the upper Paleozoic rock units from the Kaibab Limestone through the Redwall Limestone have thus far been exposed.  And because the fold has been less eroded, the upper, down-to-east bending, and lower, flattening out of the rock layers can readily be observed.  In the middle distance, on the far eastern side of North Canyon, one can easily see that the rock layers are tilted upward toward you into a series of fin-like features that geologists call hogbacks (Figure 2B.2).  The dipslope of the rock layers (the Kaibab Limestone in this case) forms the eastern flank of the hogback, while the western flank facing you exposes the layercake of rock units dissected by the formation of North Canyon.  Further east, you can see the Marble Platform, capped by flat-lying Kaibab Limestone, and the dark defile of the Colorado River’s Marble Canyon.  In the distance, on a clear day, this viewpoint also affords a nice view of Navajo Mountain, a middle Tertiary laccolithic intrusion (one of many on the Colorado Plateau); and just to the fore of that dark dome lies a long unbroken line of cliffs related to the Echo Cliffs Monocline, formed in conjunction with the one you’re standing on, but exposing younger Mesozoic sedimentary rocks.

Figure 2B.1.  Folding of upper Paleozoic sedimentary rocks into the East Kaibab Monocline as viewed from the East Rim Viewpoint.

 

Figure 2B.2.  The East Kaibab Monocline has been hollowed out by erosion of North Canyon to allow a intimate view of the nature of monoclinal folds; the upper Paleozoic sedimentary rocks exposed in the upper part of the fold limb are bent downward to the east (just east of the fold axis), are tilted down-to-the-east in the exposed western flank of the hogbacks on the far side of North Canyon, and then flatten back out to the horizontal on the Marble Platform.

 

When you return to the East Rim Viewpoint parking area, you may wish to walk down the entrance road, cross the main road, and walk a short distance to the north (maybe 100-150 yards) for a great look at a large sinkhole formed in the Kaibab Limestone, one of the largest I have seen on the Kaibab Plateau.  The depression is clearly visible on Map 2B.2).  Cool, most conditions on the plateau provide a favorable setting for dissolution of the limestone.  Sinkholes can form gradually by progressive widening of surface fractures combined with slope wash into the growing depression, or they can form suddenly, by collapse of a subterranean cavity when the roof grows to thin to support its own weight.  Now return to your car and drive back to the intersection of FS Rd 611 and FS Rd 610.

 

6.8 (2.7)      Intersection of FS Rd 611 and FS Rd 610.  This time, you will turn right (south) onto FS Rd 610.  To reach AZ Hwy 67, just continue straight on FS Rd 611.

 

11.6 (4.8)     Refer to Map 2B.3.  The road makes a 90º-bend to the left, then shortly makes a 90°-bend to the right, and just after the second bend, it arrives at a parking area and trailhead for the Arizona Trail.  This National Scenic Trail travels north-south, the length of the state, but passes through Grand Canyon National Park and traverses the Kaibab Plateau in the process.

 

Just ahead, the road crosses two dry washes, grassy meadows really, that drain into Upper North Canyon.  In the fall, the Quaking Aspen growing along the verges of the forest turn bright yellow and make for gorgeous scenery (Figure 2B.3), a sight not uncommon along the roads through Kaibab National Forest.

Figure 2B.3.  Quaking Aspen turning golden yellow, common sight on the Kaibab National Forest in October, making this area a great fall color tour destination.

 

12.1     FS Rd 610 becomes straight as an arrow here as it begins paralleling the national park boundary (0.5)      just to the south of the road.

 

13.6 (1.5)     Junction of FS Rd 610 and FS Rd 219 on the left (north).  FS Rd 219 takes you to Marble Viewpoint, a spectacular overlook onto the East Kaibab Monocline that offers a three-dimensional perspective on the fold unlike any other, and an awe-inspiring campsite you may just not want to pass up.  The road is rough in places, but careful driving will take any car to your destination.  Turn left onto FS Rd 219.

 

14.2 (0.6)     FS Rd 219A splits off to the left here; remain on FS Rd 219 to Marble Viewpoint.

 

16.7 (2.5)     Refer to Map 2B.2.  The road makes a gradual right-hand bend, and at this location it is as close another huge sinkhole developed in the Kaibab Limestone near the East Rim.  This one even has earned its own name, Marble Sinkhole, perhaps because it often contains water in an otherwise generally waterless area.

 

18.1 (1.4)     FS Rd 219 reaches the posted Marble Viewpoint here.  The best views are found a short walk (or drive) down FS Rd 219AB to the right.  Good campsites can be found to either side of the promontory of Kaibab Limestone forming the viewpoint (but bring your own water supply); although the west side is less windy, the east side has the better view.

 

Marble Viewpoint probably offers the best location for observation of the East Kaibab Monocline in or out of the park, and it may well offer one of the most spectacular locations for viewing monoclinal folding anywhere.  When you walk to the end of the promontory, literally looking like its formed of crumbling white marble, your viewing platform looks almost due north, parallel to the axis of the monoclinal fold (Figure 2B.4).  One can easily observe the nearly horizontal layers of Paleozoic sedimentary rock coming in from the left (west), and suddenly, they bend downward to the east across the fold axis, only to flatten out once more on the Marble Platform.  Looking to the northeast, The Cocks Combs form several rock fins known as hogbacks that seem to protrude from the ground.  These features form where rocks are tilted on edge, erosion exposes the rock layers, forming an asymmetric hill.  The gentle side occurs on the dipslope of a resistant tilted layer, in this case the Kaibab Limestone, while the steep side exposes the internal layering of the rock units.  Hogbacks form along the strike of the fold, parallel to the fold axis.

Figure 2B.4.  The East Kaibab Monocline as seen from Marble Viewpoint; the view is to the north, parallel to the fold axis and the eastern edge of the Kaibab Upwarp.

 

Consider for a moment the formation of this enormous fold in the earth’s crust.   Compressional tectonic forces cause folding, and in many cases such as the one viewed here, compression causes the activation or reactivation of long buried faults.  Faults deep in the crust that move and subject overlying rocks to folding.  The East Kaibab Monocline formed in such a way (Figure 2.3).  East-west compression brought on by the Late Cretaceous-Early Tertiary Laramide Orogeny reactivated ancient faults in the brittle crystalline basement as reverse faults, faults underlying the softer, more ductile Paleozoic and Mesozoic sedimentary rock cover.  Reverse movement wrinkled the crust above, generating monoclinal folds in the sedimentary rocks.  Concurrent and subsequent erosion removed much of the sedimentary cover and exposed the folds and even some of the faults which caused them.

 

22.6 (4.5)     Refer to Map 2B.3.  Return to the junction of FS Rd 219 and FS Rd 610.  Turn left onto FS Rd 610 to continue your tour (or head right if you wish to return to AZ Hwy 67).

 

From here to the Saddle Mountain overlook and upper trailhead for the upper Nankoweap Trail, FS Rd 610 hugs a narrow corridor of Kaibab National Forest between the Saddle Mountain Wilderness on the left and Grand Canyon National Park on the right.  The road becomes more primitive, but still passable for street cars, and it feels increasingly like you are in the middle of nowhere.  However, a return to civilization looms at the overlook and trailhead which usually has several vehicles in the parking area.

 

23.3 (0.7)     The road makes a right-angle bend to the right here.  On the left at the bend, a sign at a short spur road indicates that the trailhead for South Canyon occurs here.

 

28.9 (5.6)      Refer to Map 2B.4.  The end of the road.  You have reached the Saddle Mountain overlook and upper Nankoweap Trailhead.  Park your car and walk the short distance to a prominent rocky knob perched on the rim of Nankoweap Canyon, or if you feel so inclined, hike a short section of the Nankoweap Trail through the intervening saddle and to the top of the bald promontory before you for more stellar views.

 

The scenery to the left (northeast) of the knob is pretty, green with lush grasses and the young growth of Gamble’s Oak after a recent fire burned this area (Figure 2B.5); but the vista to the right (southeast) into the northern branch of Nankoweap Canyon is incredible (Figure 2B.6).   Look northward, you can see that erosion has not had time to reveal much evidence of the East Kaibab Monocline.  The verdant growth in this view contrasts sharply with the brown tableland of the Marble Platform below, giving rise to the concept of “island” biogeography, mountainous terrain where the climate is cool and moist covered in forest, surrounded by a sea of hot, arid grass- and shrubland where prevailing conditions prevent tree growth.

Figure 2B.5.  A pleasant, if not geologically significant view to the northeast from the Saddle Mountain overlook.

 

Figure 2B.6.  The northern branch of Nankoweap Canyon as viewed from the Saddle Mountain overlook; here, the canyon exposes the entire package of Paleozoic sedimentary rocks, the underlying sedimentary rocks of the Late Proterozoic Chuar Group, uppermost part of the Grand Canyon Supergroup, plus ample evidence of faulting and associated folding.

 

Now compare your northern view with the one offered to the southeast where Nankoweap Creek and its tributaries have carved a deep basin, passing completely through the Paleozoic sequence and into Late Proterozoic sedimentary rocks of the Grand Canyon Supergroup, revealing the Butte Fault, Chuar Syncline and plenty of evidence of folding (Figure 2B.6).  This perch above Nankoweap Canyon provides the best view of Nankoweap Butte and the Chuar Syncline that the national park or national forest has to offer.  Look straight down the north fork of Nankoweap Canyon, follow its wash to its confluence with the main stem of the drainage coming in from the right.  Directly above the confluence is Nankoweap Butte, comprised of the up-curved layers of the Kwagunt Formation and a thin cap of Sixtymile Formation (Figure 2B.7).  These sedimentary rocks form the last two units of the Chuar Group, the uppermost layers of the Grand Canyon Supergroup, and their folding forms the Chuar Syncline.  The syncline was generated by Late Proterozoic crustal extension and normal faulting associated with the Butte Fault which abuts the Supergroup rocks on the eastern flank of Nankoweap Butte.

Figure 2B.7.  Nankoweap Butte, just to the southeast of the confluence of Nankoweap Creek and its major northern branch, displays the folded Kwagunt and Sixtymile Formations, uppermost sedimentary rock units of the Chuar Group and Grand Canyon Supergroup; folding is identified as the Chuar Syncline, formed by crustal extension and normal faulting on the Butte Fault about 740 million years ago.

 

43.3 (14.4)   Refer to Map 2B.1.  Return to the four-way intersection of FS Rd 611, FS Rd 22, and AZ Hwy 67.  Turn left to reenter Grand Canyon National Park, or right if you’re on your way to new destinations.

 

Road Route Maps

Map 2B.1.  Color shaded-relief map of the De Motte Park, AZ 7.5 minute quadrangle.

Map 2B.2.  Color shaded-relief map of the Dog Point, AZ 7.5 minute quadrangle.

Map 2B.3.  Color shaded-relief map of the Little Park Lake, AZ 7.5 minute quadrangle.

Map 2B.4.  Color shaded-relief map of the Point Imperial, AZ 7.5 minute quadrangle.