This little outing is truly for those that seek roads less traveled. The route follows good forest service roads the entire way, gradually descending the dip slope of the Kaibab upwarp’s western flank (Figure 2.1 of FIELD GUIDE TO THE GEOLOGY OF THE NORTH RIM). Not many make this trek, a few hunters and color change enthusiasts during the fall, and those few backpackers tired of the South Rim’s more heavily utilized trails that plan to hike the North Rim’s popular Deer Creek and/or Thunder River Trails. However, if you are in the mood for a bit of solitude, and an escape from the traditional, crowded overlooks elsewhere on the North Rim, I offer you this gem. Personally, I think the overlook and campsite at Crazy Jug Point has some of the most geologically interesting views on the Grand Canyon’s North Rim, as it looks due south along the Muav Fault and axis of the Crazy Jug Monocline right past Fire Point (a highlight of Field Trip 2C) and all the way to Powell Plateau. This fault-fold combination was formed by uplift and deformation of the Paleozoic and Mesozoic sedimentary cover 80-40 million years ago during the Laramide Orogeny, and now the structures lay like a jagged scar on the landscape, exposed to view by the marvelous power of time and erosion. When you combine Crazy Jug Point with Monument Point just down the road, the scenery and geology just get more intriguing. Monument Point also hosts the trailhead for the Bill Hall Trail which most hikers take to connect with the Deer Creek and/or Thunder River Trails. It is also possible to turn this set of trails into a lollipop loop hike by merging the Deer Creek and Thunder River Trails with a connecting route along the Colorado River from the mouth of Deer Creek and Tapeats Creek.
While Crazy Jug and Monument Points can be easily accessed on a long day-trip from your comfortable campsite at North Rim Campground, consider making this area an alternate choice for a night or two, the sunrises and sunsets are spectacular, and since the rim here is in the Kaibab National Forest, dispersed camping costs only the effort of getting here. The roads necessary to reach both overlooks are gravel surfaced and offer a solid tread for all types of vehicles and there are other places to camp with similar views should Crazy Jug Point be occupied. Take in the beautiful drive through conifer forest trimmed with aspen groves and grassy meadows, enjoy the breathtaking views, and contemplate the evidence preserved on the landscape and in the rocks of past and present geological forces at play.
0.0 (0.0) Refer to Map 2D.1. Return to the four-way intersection of AZ Hwy 67, FS Rd 22, and FS Rd 611 located near the center of 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 and bison out, forms an almost perfectly circular lake occupying a sinkhole at the northwest quadrant of the intersection. De Motte Park occupies the east edge of a crustal slab exhibiting down-to-the-east movement along the De Motte Fault with the high ground to the right-hand (east) side of the meadow forming the fault scarp on the uplifted block. Turn left (west) from AZ Hwy 67 onto FS Rd 22.
2.1 (2.1) Five forest service roads intersection at the junction. FS Rd 22 crosses from the southeast (where you enter the intersection) and passes to the west (straight ahead). Ignore all other routes and continue straight on FS Rd 22.
In about two-tenths of a mile, the road crosses a large north-south oriented clearing with only a smattering of trees and brush, looking much like a huge clearcut. Not so, this is naturally produced feature, known as The Blowdown, was probably caused by a thunderstorm-induced wind shear event that toppled the trees.
5.1 (3.0) Your route passes several sinkholes on the right. Here, the second sinkhole is close to the road and the forest cover thin enough to see the grass-floored, semicircular depression (the third one is just ahead). Sinkholes are a sign of karst processes at work. They form where subaerially exposed limestone is dissolved by rainfall and groundwater soaked into the rock. Sinkholes may form as a gradually expanding and deepening, funnel-shaped depression from the surface downward (as limestone is slowly dissolved from below), or it may form suddenly by catastrophic collapse of the roof above a subterranean dissolution cavity. A quick consultation of Map 2D.1 reveals more sinkholes in the area; the cool, moist climate and extensive exposure of the Kaibab Limestone are conducive to karst formation.
8.1 (3.0) FS Rd 22 passes the entrance road to Dry Park Lookout Tower on the left (FS Rd 422C). Turn left onto FS Rd 422C for a brief visit. If you have never climbed a forest fire watchtower, now is your chance. If you arrive in the morning before the hazy skies settle in, the views from the top aren’t bad either, making this an interesting stop.
Park near the tower; it should be open for climbing, but if the gate is closed don’t trespass and don’t disturb the forest service personnel in the residence cabin who may be off duty. The climb looks imposing (Figure 2D.1), but from the top of the tower you gain a 360° panorama of the Kaibab Plateau. There’s not much to see eastward, the broad back of the Kaibab Plateau climbs higher in that direction. To the south, you can see just a taste of the Grand Canyon, but the mountains of the San Francisco Volcanic Field are visible beyond the canyon. To the west, you can see the grayish-green silhouette of the Mount Trumbull Volcanic Field on the horizon; Dry Park’s grassy meadowland cuts a north-south path in your near your position. Perhaps your best view is northward, in the hazy distance are the brownish cliffs of the Grand Staircase, and in the foreground, the gently westward dipping back of the Kaibab Upwarp, broken by a northward trending divot in landscape. This feature is Lookout Canyon formed along the Big Springs Fault (Figure 2D.2); Dry Park merges with the canyon not far north of your position, Dry Park’s swath of meadow continuing the trend of the Big Springs Fault to the south. The upthrown side of the fault is to the east, with rocks on the west side curved slightly downward toward the east in the barely perceptible Big Springs Monocline. The lookout tower is situated on the upland formed by the fault’s uplift.
Figure 2D.1. The steel-framed Dry Park Lookout Tower rises into a clear blue sky near Dry Park, a large elongated meadowland on the Kaibab Plateau; the forest fire watchtower is situated on the upland formed on the upthrown side of the Big Springs Fault.
Figure 2D.2. Dry Park Lookout Tower offers a 360° panoramic view of the Kaibab Plateau, with the most interesting view to the north along Lookout Canyon which has carved its course along the Big Springs Fault; note that the fault displacement is down-to-the-west.
8.8 (0.7) Side trip over, return to FS Rd 22 and turn left (north) to continue your trip.
10.4 (1.6) FS Rd 22 enters the northern end of the elongated Dry Park meadowland. The grass-covered valley ends just to the north where it drains into Lookout Canyon. Much of the floor of this valley is comprised of Toroweap Formation mudrocks. An inspection of the geology map for the eastern Grand Canyon indicates that most of the large meadows on the Kaibab Plateau are similarly floored, suggesting an interesting correlation between vegetation type and rock type. Conifers prefer the drier conditions of the porous Kaibab Limestone which rapidly soaks up the available moisture, grasses prefer the mudrocks of the Toroweap whose soils retain more moisture (Figure 2D.3).
Figure 2D.3. Dry Park, an elongated grassy meadow underlain by moisture retaining soils developed on mudrocks of the Toroweap Formation where the rock unit is exposed along the trace of the Big Springs Fault.
11.2 (0.8) Refer to Map 2D.2. After crossing Dry Park, the road comes to a “Y” junction; FS Rd 206 heads south (left) here. Continue northwest (right) on FS Rd 22.
FS Rd 22 now pursues a course along a ridgeline that lies on the west side of the gradually deepening Lookout Canyon. The canyon has carved a distinctly linear valley along the trace of the Big Springs Fault which trends NW-SE in this area, counter to the general westward slope of the Kaibab Plateau. Notice that the watersheds west of the ridgeline you traverse are all oriented east-west, as they should, such as Parissawampitts Canyon, their orientation matching the down-to-the-west dip of the rock layers on the west side of the Kaibab Upwarp.
18.3 (7.1) Refer to Map 2D.3. Cruising for some distance along the west side of Lookout Canyon, you eventually come to a major “T” junction with FS Rd 425, your access to Crazy Jug and Monument Points. Turn left (west) here onto FS Rd 425.
20.9 (2.6) The road swings to the right here as it begins to descend from its ridgeline path into Big Sowats Canyon.
The geology of this canyon is significant and should be pointed out. As you can see from Map 2D.3, the canyon drains westward off the back of the tilted Kaibab Plateau as expected, but then hits the north-south trending Muav Fault and Crazy Jug Monocline. The fault scarp can readily be observed on Map 2D.4 and Map 2D.5 where the abrupt change in elevation occurs. Naturally, the stream which carved Big Sowats Canyon took the path of least resistance, as all good streams will do, and for that reason, its trend was forced to follow the fault. The stream and its canyon can plainly be seen to veer abruptly away from the Grand Canyon’s rim and flow northwest. The new direction of the drainage is northwest off the back of the crustal block on the downthrown side of the Muav Fault which is tilted slightly to the northwest.
Note: the road crosses the southeast corner of Map 2D.4, although there are no mileage markers. The map is provided for continuity and the above discussion regarding fault-controlled drainage patterns.
As you descend Big Sowats Canyon, you may notice the distinctly different vegetation to either side of the valley. The north-facing slopes are still covered in ponderosa pine, but the south-facing slopes are dotted with brush and junipers. This vegetation contrast is related to microclimatic variation, with the sunny, south-facing slopes now too dry to support ponderosa at these lower elevations.
24.3 (3.4) Refer to Map 2D.5. FS Rd 427 lies to the right-hand (north) side of the road here at the junction of Big Sowats Canyon and a major tributary coming in from the left (south). Your route swings 90° to the left into this tributary which has formed along the trace of the Muav Fault. FS Rd 425 now parallels the fault on its downthrown side and the fault scarp lies directly to the left (east).
The Muav Fault also forms the geographic boundary between the Kaibab Plateau to the east and the Kanab Plateau to the west (Figure 2D.4). This latter plateau is so named from Kanab Creek which drains much of its surface (the course of Big Sowats Canyon eventually merges with Kanab Creek off to the northwest). The Kanab Plateau is generally much lower in elevation and considerably drier than the Kaibab, except for a small wedge in its southeast margin near the Grand Canyon’s rim which you are about to visit.
Figure 2D.4. A satellite image of the Grand Canyon region showing the unusually broad, flat plateaus which surround and define it, plateaus formed by uplift and bounded by faults such as the Muav Fault separating the Kaibab Plateau from the Kanab Plateau.
26.7 (2.4) FS Rd 425 enters the lower end of a small meadow here that once contained an artificial reservoir. The “Y” junction at this location splits FS Rd 425 to the right and FS Rd 232 to the left. FS Rd 232 takes you to Indian Hollow campground and trailhead. This is the official trailhead for the Thunder River Trail, but you can save some hiking time and effort by taking the shorter Bill Hall Trail into the canyon which is accessed via the trailhead at Monument Point. Continue to the right on FS Rd 425.
28.4 (1.7) A small artificial reservoir occurs in a grassy clearing to the right side of the road here. FS Rd 425 takes an abrupt left at this point, do not follow it! Instead, continue straight ahead on the obviously better used FS Rd 292.
28.6 (0.2) Another “Y” junction at this point splits FS Rd 272 to the left, and FS Rd 292 to the right; remain on FS Rd 292.
29.9 (1.3) Four-way intersection. FS Rd 292A continues straight ahead for Monument Point, but for now, turn left onto FS Rd 292B and make for Crazy Jug Point. Stay to the left just ahead at yet another fork in the road and you’ll soon reach the overlook and small camping area.
30.1 (0.2) Crazy Jug Point; at last, now you can get out and explore! If you are making this drive as just a day trip, it really doesn’t matter which overlook you visit first, but if you’re intention is to camp overnight, Crazy Jug is the better location. It is a long drive to the Bill Hall Trailhead from civilization, so Crazy Jug serves as a good staging point for any backpacking trip on the Deer Creek and/or Thunder River Trails.
A trail at the far end of the small loop in the road takes you to the actual overlook. A long narrow ridge extends from Crazy Jug Point into the canyon, so your view of the Tapeats Amphitheater is more or less cut into two fairly equal portions. To see downstream along the main Grand Canyon, including the western half of the Tapeats Amphitheater and the bulk of the Tapeats Creek drainage, head to the right side of the overlook first (Figure 2D.5). The dividing ridge is on the left edge of the photograph, pointing directly at Steamboat Mountain on the far side of a deep defile; this east-west oriented canyon belongs to Tapeats Creek. The deep canyon joining it from the right-hand side of the view is a tributary of Tapeats Creek dissected along the north-south trending Tapeats Fault. Oddly, Tapeats Canyon flows almost due west across both the Muav and Tapeats Faults, suggesting its drainage was established long ago on the westward sloping back of the Kaibab Upwarp. The flat-topped, tapered butte of Steamboat Mountain with its distinctive circlet of whitish Coconino Sandstone cliffs is an isolated remnant of the Kanab Plateau west of the Muav Fault. Behind Steamboat, you can see the long arm of Powell Plateau, also west of the Muav Fault, stretching to the southwest. The Colorado River makes a very strange dodge, with enormous looping curves, around the outskirts of Powell Plateau and comes in from the south, almost in the center of the photo, only to curve off to the west (right). Further to the right (not shown on Figure 2D.5) lies Monument Point, while the mountains of the Uinkaret Volcanic Field can be seen on the skyline, famous for its outpourings of basaltic lava that flowed into the Grand Canyon and temporarily dammed the Colorado River (visited on Field Trip 3).
Figure 2D.5. The western portion of the Tapeats Amphitheater and much of Tapeats Canyon as seen from the right-hand side of the overlook at Crazy Jug Point.
Now let’s head to the left side of the overlook; the view is more interesting there. The large basin below you is the eastern half of Tapeats Amphitheater. Look to the east (left as you face the canyon) at the Grand Canyon’s rim across from your position. It is not at all difficult to make out the long, narrow canyon at the base of the cliffs; this is Crazy Jug Canyon (Figure 2D.6). Follow that canyon southward and it runs into another canyon at right angles to it (Figure 2D.7), this new canyon is the east end of Tapeats Canyon and the smaller canyon that continues south from the canyon junction is Saddle Canyon. To the east of Tapeats Canyon lies Stina Canyon, which then joins Quaking Aspen Canyon as you head back up onto the Kaibab Plateau. Together, these three canyons form a westward flowing drainage that cuts across the north-south oriented Muav Fault (and Tapeats Fault further west). The drainage may have been established on Early Cenozoic or Mesozoic rock layers undisturbed by faulting that dipped down-to-the-west on the western flank of the Kaibab Upwarp. Saddle Canyon and Crazy Jug Canyon on the other hand, were clearly established along the trace of the Muav Fault, an obvious zone of weakness in the rock easily exploited by running water. This suggests that their courses were established later, after erosion had stripped enough rock from the Kaibab Upwarp to expose buried faults. Looking further afield, to the south you can see Steamboat Mountain rising above Tapeats Canyon and to the right (east) and behind Steamboat is Powell Plateau (Figure 2D.7). Both Steamboat Mountain and Powell Plateau are separated from the North Rim by the Muav Fault which passes directly through the eroded V-shaped notch in the rimrock just east of Powell Plateau called Muav Saddle. A careful eye may note that the sedimentary rock layers on the west side of Crazy Jug and Saddle Canyons curve downward to the east into the stream canyon (trace the Coconino Sandstone cliff-band west to east); this is evidence of the Crazy Jug Monocline which sits above the Crazy Jug Fault (the fault not exposed by erosion in the area, but compression and uplift of the crustal block west of the fault during the Late Cretaceous to Early Tertiary Laramide Orogeny produced the monoclinal folding of the Paleozoic rocks above.
Figure 2D.6. Crazy Jug Canyon from Crazy Jug Point; the canyon connects to Saddle Canyon to the south and the alignment of the two canyons matches the position of Muav Saddle (separating Powell Plateau from the North Rim), and all three features denote the north-south trace of the Muav Fault.
Figure 2D.7. The eastern half of the Tapeats Amphitheater from Crazy Jug Point; your view encompasses Crazy Jug Canyon and its right-angle connection with Tapeats Canyon in the near ground, and the North Rim, Muav Saddle, Powell Plateau, and Steamboat Mountain in the background.
Let’s have another look at the cliffs and slopes below the North Rim on the east side of Crazy Jug Canyon (Figure 2D.6 and Figure 2D.7); on display is much of the upper Paleozoic sedimentary rock sequence. Three distinctive cliff-bands are most readily observed, the whitish-colored Kaibab Limestone which caps the rim and the Coconino Sandstone, third unit down, as well as the reddish Esplanade Sandstone which caps a thick, ledgy zone comprising the rest of the Supai Group. Between the Kaibab and Coconino is the slope-forming Toroweap Formation, and between the Coconino and Esplanade is the slope-forming Hermit Formation. The Hermit is particularly thick this far to the west in the Grand Canyon region, and because this unit is susceptible to weathering and mass wasting, it erodes rapidly, undercutting the more resistant Coconino cliffs above. Careful observation indicates that the Tapeats Amphitheater is floored by the Esplanade Sandstone, another rock layer resistant to erosion (Figure 2D.5 and Figure 2D.7). Rapid backwasting of the overlying rock units quickly exposed this surface over a broad area to form the expansive shallow basin of the Tapeats Amphitheater. One of the unique and delightful features of the Deer Creek-Thunder River Loop (accessed from Monument Point’s Bill Hall Trail) is hiking on the broad, gently undulating surface of the Esplanade Sandstone where it is widely exposed west of the Tapeats Amphitheater.
Of course, the superb geology is not the only reason to enjoy a stay at Crazy Jug Point. Sunsets are quite spectacular (Figure 2D.8 and Figure 2D.9); try to imagine this scene, you, your favorite someone, a blanket, and a bottle of wine with the Tapeats Amphitheater as your backdrop…perfect! Or bring the whole family; it’s never too early to expose the kids to the world of geology, and what place could serve as a better classroom. After an amazing stay at Crazy Jug Point (hopefully you got the opportunity to overnight there), Monument Point remains on the agenda.
Figure 2D.8. A striking sunset glow on the east wall of the Tapeats Amphitheater rivals many locations in the Grand Canyon.
Figure 2D.9. The sun sets over Mount Trumbull far to the west on the Uinkaret Plateau, Monument Point, Bridger’s Knoll and the western Tapeats Amphitheater lying darkened in the foreground.
30.4 (0.3) Return to the four-way intersection of FS Rd 292, 292A and 292B. Don’t go straight ahead! FS Rd 292 on the right takes you back to FS Rd 22 and your way out, and FS292A on the left heads for Monument Point. It’s not far (you’re so close) and the view is worth the effort; turn left (west) and make for Monument Point.
32.1 (1.7) Monument Point parking area. Monument Point hosts the trailhead for the Bill Hall Trail, the main entry point for a backpacking trip on the Deer Creek and/or Thunder River Trails (see Deer Creek-Thunder River Loop under Optional Hiking Trail 2D.1). However, a short hiking trail of about a mile round-trip is all that is necessary if you’ve come to catch the views from Monument Point.
To reach the overlook, start walking west along the rim on the Bill Hall Trail from the first saddle in the ridge where the parking area is located to a high point ahead. The skeletal remains of juniper indicate that the area was recently burned and only grasses and brush like Gambles Oak have recolonized, leaving the area devoid of trees except a few nearest the rim that escaped the blaze. You are almost immediately treated to a great view of the Tapeats Amphitheater (Figure 2D.10). The view from here skirts along the rim to the west toward Monument Point and the pencil-thin ridge of Coconino Sandstone forming Bridger’s Knoll below, and swings eastward into the western part of the Tapeats Amphitheater. Steamboat Mountain lies is shadow at the left edge of the photograph, while the deeply entrenched canyon of lower Tapeats Creek takes center stage to the south as you look down the axis of its tributary eroded along the trace of the Tapeats Fault. Tapeats Canyon itself trends slightly northwest and is dissected across this fault, and then bends southwest before its confluence with the Colorado River. The Inner Gorge of the Colorado lies below the prominent cliffs of Great Thumb Mesa on the Grand Canyon’s South Rim, which can be seen behind Bridger’s Knoll.
Figure 2D.10. The western portion of Tapeats Amphitheater and lower Tapeats Canyon from the saddle in the Kaibab rim near the beginning of the Bill Hall Trail; the view includes Bridger’s Knoll in the west and sweeps around to Steamboat Mountain in the east.
Continue walking along the rim past a high point on the ridge and through a second, smaller saddle. In short order you reach the rock cairn and signage for the Bill Hall Trail. If you are hiking the Deer Creek and/or Thunder River Trails using the Bill Hall Trail as a shortcut, drop your backpack and pass the trailhead junction for now. Walk to the obvious promontory a couple hundred feet ahead. When you reach Monument Point, you are immediately drawn to Bridger’s Knoll which lies directly below your perch (Figure 2D.11). This fin of Coconino Sandstone points like an arrow almost directly to the mouth of Tapeats Canyon and the east end of Great Thumb Mesa. The inner gorge of the Colorado River, flowing in a northerly direction toward you, lies just east of Great Thumb Mesa. Tapeats Canyon can be seen cutting deeply through Supai Group rocks, Redwall Limestone, and Muav Limestone to the southeast of Bridger’s Knoll (Figure 2D.12). Perhaps the most striking view from Monument Point lies to the west. Here, the panorama takes in the volcanic mountains of the Uinkaret Plateau in the distance and an enormous shallow basin floored by the broad expanse of the Esplanade Platform in the foreground (Figure 2D.13). The geomorphic processes involved are very similar to those where the Bright Angel Shale rests on Tapeats Sandstone which forms the Tonto Platform in the eastern Grand Canyon. However, here, rapid weathering and mass wasting of the mud-rich Hermit Formation allowed backwasting of the overlying rock units which quickly exposed the Esplanade Sandstone over a considerable area to form the benchland of the Esplanade Platform. The deeper canyons draining the platform north of the Colorado River constitute the Deer Creek watershed (Figure 2D.13). The Bill Hall Trail descends to the Esplanade Platform, then joins the Thunder River Trail coming in from Indian Hollow to the west. The Thunder River Trail then skirts to the right (east) around the canyons of upper Deer Creek, eventually dropping over the edge of the Esplanade rim near the photograph’s center.
Figure 2D.11. Bridgers Knoll below Monument Point forms a the narrow ridge capped by Coconino Sandstone that is aligned closely with the mouth of Tapeats Creek and the end of Great Thumb Mesa on the Grand Canyon’s South Rim.
Figure 2D.12. The western portion of the Tapeats Amphitheater and lower Tapeats Canyon from Monument Point.
Figure 2D.13. The downcanyon view from Monument Point reveals a truly unique landscape that few visitors to the Grand Canyon ever witness; here, the familiar grayish benchland of the Tonto Platform is replaced by the similarly formed brick-red benchland of the Esplanade Platform at a higher position in the Paleozoic sedimentary rock section.
As you look west, notice that the Inner Gorge of the Grand Canyon has changed considerably from the classic North and South Rim viewpoints well to the east (Figure 2D.13). Now the Tonto Platform is gone and the Redwall Limestone closes in to very near the river because the Bright Angel Shale is much thinner here and doesn’t play much of a role in canyon widening as it does upriver. Instead, as we’ve discussed, the thickened Hermit Formation has taken over that role forming the Esplanade Platform which you can see sailing downriver for a considerable distance. Look closely at the inner gorge near the center of the photograph, hopefully you can make out the grayish dome peeking above the Esplanade rim from within the gorge. This dome is Cogswell Butte on the north side of the river, comprised of an isolated remnant of Redwall Limestone with a thin veneer of lowermost Supai Group rocks. The butte sits at the outer edge of Surprise Valley, nearest the river. Surprise Valley hides a massive landslide produced by collapse of a huge slab of Supai Group and Redwall Limestone that peeled away from the cliff face of the inner gorge long ago. The Thunder River Trail drops into Surprise Valley, traversing the landslide debris, and then heads east (upriver) and into Tapeats Canyon, passing Thunder River along the way, a perennial stream that originates from a continuously gushing torrent of groundwater issuing from the base of the Muav Limestone. The Deer Creek Trail splits from the Thunder River Trail in Surprise Valley and heads west (downriver) and into lower Deer Creek. The two trails can be connected by a river route to form the popular Deer Creek-Thunder River Loop.
Sadly, one must return to civilization from this distant and magical place. When you have seen enough turn around and return to the parking area, there is yet more to see and contemplate on your way out.
33.8 (1.7) Return one last time to the four-way intersection of FS Rd 292, 292A, and 292B. Continue straight ahead on FS Rd 292 (do not take the branch to the left), eventually rejoining FS Rd 22. But first, if you missed Crazy Jug Point on your way in, turn right onto FS Rd 292B and take a few moments to visit the overlook, it’s quite spectacular.
35.1 (1.3) The “Y” junction here splits FS Rd 272 to the right and FS Rd 292 to the left; remain on FS Rd 292.
35.3 (0.2) Recall the small artificial reservoir in a grassy clearing to the left side of the road. FS Rd 292 takes an abrupt right at this point, do not follow it! Instead, continue straight ahead on the obviously well used FS Rd 425. Remain on FS Rd 425 all the way to its junction with FS Rd 22.
45.5 (10.2) Refer to Map 2D.3. “T” junction between FS Rd 425 and FS Rd 22. Turn left onto FS Rd 22. If you plan to return to Grand Canyon National Park’s North Rim facilities, turn right here instead and follow FS Rd 22 all the way to AZ Hwy 67.
FS Rd 22 initially parallels Lookout Canyon along its west side for several miles, then drops from the ridge to the canyon floor at its confluence with Castle Canyon draining down from the east. At this juncture, the now enlarged Lookout Canyon becomes Nail Canyon. Lookout and Nail Canyons are developed along the trace of the Big Springs Fault.
49.5 (4.0) FS Rd 429 joins FS Rd 22 here from the right. This junction occurs just below the confluence between Lookout Canyon and Castle Canyon to form Nail Canyon. Continue downcanyon on FS Rd 22. Note the change in elevation between east and west sides of the valley you are in; displacement on the Big Springs Fault is down-to-the-west by roughly 400 feet here, although it increases northward along the fault (Figure 2D.14).
Figure 2D.14. Nail Canyon runs straight-as-an-arrow along the trace of the Big Springs Fault; displacement on the fault is down-to-the-west by roughly 400 feet here.
50.5 (1.0) Passing Big Springs Field Station on the right. Big Springs issues from the top of the Toroweap Formation at its contact with the overlying Kaibab Limestone. The Toroweap’s less permeable mudstones force groundwater seeping downward through the porous Kaibab to flow laterally down the west-facing dipslope of the Kaibab Upwarp to a point where Nail Canyon has cut below the level of the contact, allowing the groundwater to emerge from the valley slope as a spring. The spring is easily observed where a swath of verdant growth occurs above the entrance road to the field station.
As you continue driving northward down Nail Canyon, it deepens, so the contact between horizontal rock layers rises higher on the canyon wall. Occasional clearings along the valley side slopes reveal red-brown,ledgy layers of Toroweap mudstones and sandstones beneath outcrops of whitish Kaibab Limestone.
52.2 (1.7) Refer to Map 2D.6. A ranch road merges from the right-hand side of FS Rd 22 at the mouth of Mangum Canyon. A careful look at the cliff face above the ranch on the north side of the canyon shows the contact between whitish Kaibab Limestone and reddish Toroweap Formation.
53.2 (1.0) Another faint road merges from the right at the mouth of Moquitch Canyon. A well-exposed outcrop of ledgy, red-brown mudstones and sandstones of the Toroweap Formation overlain by whitish Kaibab Limestone occurs on the north east canyon wall (Figure 2D.15). Similar exposures become commonplace downcanyon.
Figure 2D.15. The cliff face on the northeast side of Moquitch Canyon offers an excellent exposure of whitish Kaibab Limestone overlying red-brown, ledgy Toroweap Formation mudstones and sandstones.
55.1 (1.9) Passing FS Rd 423 on the left. Nail Canyon makes a sharp, left-hand (westward) bend here away from the trace of the Big Springs Fault, while FS Rd 22 continues straight, up into the lower end of Oak Canyon and then over a low divide separating Nail Canyon from Warm Springs Canyon. At this point, Map 2D.6 indicates that the ridge on the western side of Nail Canyon is about 700 feet lower than the eastern side. Normal fault displacement is at least 700 feet down-to-the-west in this area.
55.8 (0.7) FS Rd 22 makes a wide 180° bend here as it crosses Oak Canyon wash. Just beyond the wash, outcrops on the right-hand side of the road expose Toroweap Formation at road level. A brief stop here verifies the layers as mudstones and thinly bedded sandstones.
57.1 (1.3) Intersection between FS Rd 22 and FS Rd 462 at the mouth of Warm Springs Canyon. FS Rd 22 can be taken all the way to US Hwy 89A just east of Fredonia, AZ. This is a recommended alternative to the route described hereafter during early spring or late fall because of adverse snow conditions. It is also paved and offers a shortcut for those heading toward St. George or Kanab, UT. Assuming that weather and/or the need for a shortcut is not an issue, turn right onto FS Rd 426 and make for the Jacob Lake junction at the top of the Kaibab Plateau on US Hwy 89A.
59.9 (1.8) Warm Springs, the namesake of Warm Spring Canyon, lies to the left of the road here just below the contact between the Kaibab Limestone and Toroweap Formation. Impermeable mudrocks in the Toroweap force groundwater that has percolated downward through the porous Kaibab Limestone to flow laterally and seep from the valley side slope.
60.8 (0.9) FS Rd 462 passes the contact between the Toroweap Formation and Kaibab Limestone here.
61.3 (0.5) “Y” junction; FS Rd 462 head right at this fork in the road, your route takes the left fork onto FS Rd 461.
66.0 (4.7) “T” junction with FS Rd 282 on the right. Driving a short distance down this road provides a quick look at Jacob Lake, a sinkhole depression that often contains some water throughout the year.
66.7 (0.7) Intersection between FS Rd 461 and AZ Hwy 67. A left turn here quickly takes you to US Hwy 89A, but don’t forget at least a brief stop at the Jacob Lake Inn for some of their tasty cookies! This ends Field Trip 2D.
Road Route Maps
Map 2D.1. Color shaded-relief map of the De Motte Park, AZ 7.5 minute quadrangle showing segments of Field Trip 2A, 2B, 2C, and 2D.
Map 2D.2. Color shaded-relief map of the Timp Point, AZ 7.5-minute quadrangle showing a segment of Field Trip 2D.
Map 2D.3. Color shaded-relief map of the Big Springs, AZ 7.5-minute quadrangle showing segments of Field Trip 2D.
Map 2D.4. Color shaded-relief map of the Sowats Spring, AZ 7.5-minute quadrangle showing a segment of Field Trip 2D.
Map 2D.5. Color shaded-relief map of the Tapeats Amphitheater, AZ 7.5-minute quadrangle showing a segment of Field Trip 2D.
Map 2D.6. Color shaded-relief map of the Warm Springs, AZ 7.5-minute quadrangle showing a segment of Field Trip 2D.
Map 2D.7. Color shaded-relief map of the Jacob Lake, AZ 7.5 minute quadrangle showing segments of Field Trip 2A, 2D, and 2E.