Earlier that day (the same day I stopped in Parachute and Rulison, resulting in threeposts about the Roan Cliffs), I had pulled over at the convenient viewing pullout on I-70, which is east of Grand Junction and a bit west of Palisade. It's hard to pass by this cliff, part of the Book Cliffs, without taking a picture or two. This time, unlike most other times, I took only one photo!
The Book Cliffs are capped by sandstone and lesser shale of the Upper Cretaceous Mesaverde Group, which overlies shale and minor siltstone and sandstone of the Upper Cretaceous Mancos Shale. The Mesaverde Group (sometimes Formation, see Geolex) usually consists of several recognized sandstone tongues, members, and formations, with intertongues of Mancos Shale in its lower part. In the area of these photos, the mapped sandstone formation—the buff-colored cliff-former above the Mancos—is the Mount Garfield Formation, obviously named for Mount Garfield, the highest point above the cliffs, on the upper left.
I cropped the photo to zoom in, partly because the nearly white layer just below the sandstone cliff caught my eye. While here, we might as well take a peek at the geologic contacts.
Other photos of mine of the Book Cliffs can be seen here (photos from 2006) and here (photos from 2008). Also check out Ron Schott's GigaPan of the cliffs.
I was looking back through some photos and realized I had some of the Roan Cliffs from the spring of 2006. These first two photos are taken from an impromptu campsite MOH and I found not far from the Rulison exit on I-70, and they somewhat approximate the views seen in Ron Schott's excellent gigapan of the cliffs. I'd embed the gigapan here, but Blogger seems to have some problem with either the iframe coding or the flash implied within the code (or maybe it's Chrome, and I'm being deluded as to what's possible). In either case, we're looking northwest toward the cliffs in the first photo (above), and northeast toward the cliffs in the second photo (below).
It was a very green spring, according to these photos, so the color balance doesn't match with my fall 2016 photos below, which were taken from near or at the Rulison exit. Also, my Nikon tends towards blue.
The reason I stopped for these particular photos during my semi-mega roadtrip of last fall was the talus. I found the striping caused by alternating zones of vegetated and non-vegetated slope areas to be fascinating in the way that perhaps only a geologist, geomorphologist, or photographer can. So I grabbed a few quick shots focusing largely on the talus slopes. More recently, I decided some approximated geologic contacts were in order.
In this photo (above), the cliff and talus slope below the cliff are formed on the Tertiary Green River Formation (Tg), and the colorful beds near the bottom of the photo consist of the Tertiary Wasatch Formation (Tw). The thin cyan line near the base of the cliff marks (hopefully) the top of the Mahogany ledge as extrapolated from this USGS preliminary geologic map, as deduced from this report (Fig. 9, p. 16)—which points out the top of the ledge in a cliff to the west—and as mapped from Ron's gigapan of the cliffs. A fewotherreports were helpful for exploring the general geology and reading some background info about the ledge and zone—it's called the Mahogany zone when intercepted in drill holes.
In this set of two photos, I've zoomed in on the striped talus section that was on the far right of the previous two photos. The vertical striping of the talus contrasts nicely with the horizontal layering of the Wasatch beds, don't you think? I've labeled the photos below. This time, a tiny bit of the Tertiary Uinta Formation (Tu) is barely visible at the top right. The stratigraphic contact between the Tg and Tw is crudely outlined in faded cyan: It crops out behind the foreground slope where we can't see it.
This set of two photos is not that different from the previous set, but here (below) I've sketched in the Mahogany ledge (as approximately extrapolated), and I've broadly labeled the geologic formations without drawing in the contacts. The circle is where an old mine, the Rulison Oil Shale Mine is shown on the topo map of the area (USGS TNM 2.0 Viewer link). I can't see it there in the photo—though maybe it's just not apparent—but there is a tiny black area that *might* be an adit just beneath the arrow.
The cliffs in these 2016 photos lie northwest of the Rulison exit and occur between the first two 2006 photos.
In this last set of two photos, we're looking northeast from the Rulison exit, zooming in on cliffs that approximate what we can see in the second of the two 2006 photos. I once again focused in on striped talus, but then I really zoomed in on some switchbacked roads that I thought might be drill roads. It turns out that the switchbacks climb up to some underground workings into the Mahogany ledge, which I've marked approximately with a thin cyan line (below, with thicker lines marking formational contacts; Tu = Uinta Formation; Tg = Green River Formation). The line is taken directly from the previously linked-to preliminary geologic map of the Anvil Points Quadrangle (O'Sullivan, 1986). The map can be viewed directly in Google Earth, an option I always appreciate.
The underground workings here consist of several adits comprising the Anvil Points Oil Shale Mines. The mine was active intermittentlyfrom 1925 to 1982 (the last link includes some undated photos), with some clean-up operations running from 2008 to 2013.
How do you spell Talus-y? I see 3 options: talus-y, talusey, and talusy. I went with the first option in the title but prefer the last. Yes, I know it's not a *real* word.
In the first photo, it's still a toss-up, imo, as to whether the Tertiary Uinta Formation (Tu) can be seen—but if so, it's way up at the top of the cliff. Most or all of the cliff and most of the slope is underlain by the Tertiary Green River Formation (Tg). Aaaaand maybe there's a bit of the Tertiary Wasatch Formation (Tw) at the bottom of the photo.
In the second photo, there is (probably) just a tiny bit of the lower part of the Uinta Formation (Tu) above the cliffy area, and the reddish-brown foreground slopes are underlain by the Wasatch Formation (Tw). The rest, cliff and slope, consists of Green River Formation (Tg).
Getting back to my October-November road trip (last seen here), I stopped to get some fuel in Parachute, CO, on what was Day 7 of the trip, and I ended up taking a few photos (surprise!), partly thinking that the cliffs show good examples of bedding, and also because I was becoming fascinated by the exceptional talus slopes coming off the cliffs. The first photo is a cliff at a round nose sticking out from Mt. Callahan. The second photo is of a cliff at the southern end of a nose known as Allen Point, a long skinny ridge running about 1.5 miles south of a broader, arcuate area also called Allen Point.
When I investigated this area after my trip was over, I was surprised to find that these cliffs are part of the Roan Cliffs: while still enroute, I thought I was driving along the Book Cliffs. The Roan Cliffs are the cliffs that break south off of the broad Roan Plateau, a large plateau area that extends from Rifle, CO, to at least somewhere north of Grand Junction, possibly bounded on the west by Roan Creek. The Roan Cliffs, however, at least as shown here, encircle a broader area extending westward from Rifle, CO, to the mountains just east of the Wasatch in Utah.
The Roan Cliffs are capped by the Eocene Uintah Formation (which we may or may not see in these photos), and slopes below the uppermost cap are composed of the Eocene Green River Formation. Some of the lower, reddish slopes in the area are underlain by the Paleocene to Eocene Wasatch Formation. You can read a little more about the geology of the area in this USGS Bulletin.
The Roan Cliffs stratigraphically overlie the Book Cliffs, which we'll see later. I'm not sure how I mistook the cliffs of the Uintah Formation and upper Green River Formation for cliffs of the Cretaceous Mesaverde Group, or slopes of the Green River Formation for the usually easy-to-spot Cretaceous Mancos Shale. I can only plead that geology at 70+ mph isn't always spot-on.
Someone at US Ends.com suggested, when posting a photo of a similar sign on eastbound I-70, that there is one speed limit for regular travelers and a second, lower speed limit for dust storms.
I took this photo in 2006 on I-70 in Utah, while MOH and I were traveling in an easterly direction. The sign was located near Cisco (location way below), and it's apparently no longer there, or anyhoo it isn't shown on the current rendition of Google Street View. The Colorado River is less than 10 miles to the south of the interstate, and one happens to be driving through an upland largely underlain by Mancos Shale, which often makes paved roads lose their originally smooth surface, leaving drivers and passengers alike to feel about the same as they would while driving over bad frost heaves on the Alaskan Highway between Destruction Bay, Yukon, and Tok, Alaska.
Anyway, this is my first post in an off-and-on series of Thursday road sign posts. Many of the signs I've photographed over the years are standard mileage signs, exit signs, warning signs (curves, low flying aircraft, what-have-you), regulatory signs (stop, yield, do-this, do-that), mileposts (often photographed so I'll know where a certain roadcut or outcrop was located along the road), and other signs, some of which have nothing to do with the road (Iditarod signs, pub signs, signs on and inside buildings): anywhere signs, in other words.
I'm a little confused about which number this is: either #15 or #16. It looks like it's going down as #15, though I put #16 on my entry, and can't change that now because it's already been linked to. Not a big deal, though - we're talking millions of years; what's a little number like 15 or 16?
The sign in the photo above is at the Rabbit Creek exit, Exit 2, on I-70 in western Colorado, not far from the Colorado-Utah border. The sign points to a 1.5 mile interpretive trail loop, the Trail Through Time, where you can hike to an old dinosaur quarry (that would be a quarry dug for dinos not by dinos!). Stop by when you get a chance! I was in a hurry to get to Fisher Towers, so passed it by this time.
The Carnival of the Arid is now scheduled to be a monthly thing, to be published on the first day of every month, so consider contributing in the future, if you haven't already. A fewothers from the GeoBlogosphere, alsohereandhere, were included this month.
The photo above, is from Utah Route 28 south of I-70 on the way into Fisher Towers. The rock formation is probably Navajo Sandstone or possibly Entrada Sandstone.
If you'll go back to one of my earlier aerial views of the Fisher Towers and Professor Valley areas on the Colorado River, you'll see that I've enlarged one corner - and added in a couple lines indicating two faults that cut through the area. The faults, also seen on the geologic maps of the area, here and here, appear to be closely related to the northwest-trending Arches National Park uplift or anticline. The photo above shows the dropped down and possibly folded or slumped graben, as seen from the dirt road just below Fisher Towers. The camera was looking just a little bit south of west (WSW). And here's a little field sketch of the same faulted area, as drawn in 1997 from a slightly different angle, showing how all units in the center of the two faults have been dropped down. The cliff-forming, Jurassic Wingate Sandstone is a good marker bed to follow in the photos and in the cartoon-like field sketch.
If you drive Utah Route 128 from I-70 to Moab, you will pass right by these structures. And actually, because they cross the river and the road, you will drive right over them.
View of Fisher Towers from the trail-head parking lot.
After driving down Utah Route 128 from I-70 about 20 miles, you will come to a red dirt road and a sign pointing left toward Fisher Towers. As you probably recall, Fisher Towers is in the Richardson Ampitheater, in Professor Valley, within view of the red Colorado River. Fisher Towers and all the Permian and Triassic rocks making up the Richardson Ampitheater are very good examples of why the Colorado River sometimes runs red.
Follow the dirt road - this time of year I strongly recommend 4WD and caution - to the parking lot below the towers. A nice campground sits in the shadow of the towers, in case you want to spend the night. I thought it was a little chilly for that, however, and didn't stay. Above, an excellent view of one of the towers looming overhead, with its dark red Moenkopi cap (Triassic), and red to dark purplish red Cutler Formation walls and base (Permian). If you follow the trail from the parking lot, you can walk beneath the towers, cross gullies and drainages, and generally have a good time. Another close-up view of the towers behind a cliff in the Cutler Formation. Above, a detail of mini-towers in the Cutler Formation. In this photo, above, you can see what the Permian Cutler Formation looks like: the irregularly-bedded, orange-red to pinkish to purplish-red red beds below the red cliff of the Triassic Moenkopi, below the slope-forming Triassic Chinle Formation, which is below the Triassic Wingate Sandstone cliff at the very top of the slope. The Moenkopi Formation does not appear to be very thick at Fisher Towers. In this last photo, it consists of just the dark red cliff in the center of the view, along with the medium red cliff just below that. The Cutler Formation starts at the first sign of the slope-forming, mostly talus-covered lighter purplish or pinkish red rocks below the cliff of Moenkopi. I think that the little ledge above the dark red Moenkopi cliff is part of the Chinle Formation, but am not entirely sure of where the upper Moenkopi contact lies. Individual ledges in the Chinle can be used as local marker beds, because they can be followed for some distance. Here, the Chinle is mostly reddish, but it can be various colors, as in the Painted Desert and Petrified Forest of Arizona.
David B. Williams of Stories in Stone correctly identified the mystery area in the January-09 WITW as the Professor and Castle valleys, which are located along the Colorado River about 20 miles northeast of Moab, Utah, on backroad Route 128, which heads south from I-70 at exit 204, the westernmost of the Cisco exits. See the topographic map area here.
I've shown the original photo again, below, with major geologic units and contacts added to the duplicate photo below that. It turns out that the central portion of the area, which is the somewhat bowl-shaped Richardson Ampitheater, is underlain by the dark red Permian Cutler Formation, and that red and red-orange Triassic to Jurassic formations make up most of the rest of the picture back to about where I've drawn the Dakota Sandstone, which is Cretaceous.
Please note that the contacts between formations, especially between the Permian Cutler Formation and the Triassic Moenkopi Formation, are inexact. Additionally, the contacts between the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, and Entrada Sandstone are inexact, possibly mislocated in some places on the photo, and more complex than shown. Generally speaking, I've left out the Kayenta Formation between the Wingate and Navajo formations, and have only shown a few formations above the Entrada Sandstone for some semblance of simplicity. Do not rely on my lines for any kind of mapping in the area other than crude, for-fun stuff; instead, go to the original sources!
For precise geologic details, please see the three geologic quadrangle maps of the area, the Fisher Towers quadrangle, the Big Bend quadrangle, and the Dewey quadrangle, also referenced below. Other nearby geologic maps can be found here. I noticed geologic explanations and descriptions of map units (map legends) only on the second and third of the above quadrangles. Another, smaller-scale map, covers the entire area, the geologic map of the Moab and eastern part of the San Rafael Desert 30' x 60' quadrangles. To follow along with the general stratigraphy of the area, see the strat column below for nearby Arches National Park.
If you go to the original strat column page linked to above, you can click on any formation to find out more - possibly more info than you ever wanted to know - with lots of references and some nice photos! Also check out the ongoing series on the Colorado Plateau at Geotripper.
And hey, now for some photos! Above you can see the famous Fisher Towers, with the semi-frozen Colorado River in the foreground and the La Sal Mountains in the background. The photo was taken from Route 128 looking almost directly south, before getting into Professor Valley and the Richardson Ampitheater. For another excellent and similar view of the towers - without snow - see this post at Geotripper, which also describes the Moenkopi Formation. Fisher Towers is an awesome place, in my opinion, located on the east side of the Richardson Ampitheater. The towers are capped by the lower part of the Triassic Moenkopi Formation above the Permian Cutler Formation, which forms almost everything you see in the above photo, from the Moenkopi cap down. This view of the towers was taken from the red-dirt access road to Fisher Towers, looking more-or-less to the east.
From the towers, you can look all around the area, with the cliffs and towers behind you, and a grand 180-degree plus view in every other direction.
To the southeast, looking in the direction of Moab, which you can't actually see, you will have a great view of some mesas and spires. The mesas and spires are formed in the Wingate Sandstone, above the slope-forming Chinle and Moenkopi Formations. This mesa, with its several spires or pillars, is part of a series of mesas that separate Professor Valley from Castle Valley (see topo map). A closeup of part of the mesa shows the unusual rock formations in more detail. The pillars to the right of the central Wingate Sandstone cliff are called the Priest and Nuns, with the large man-like figure presumably being the priest. The larger pillar to the left of the Wingate cliff is called Castle Rock, and sometimes called Castleton or Castleton Tower. Perry, of Robert Perry Hooker, provided a link to a fabulous panorama taken from the top of Castle Rock.
Also, as mentioned in earlier comments, Jon Bon Jovi shot a video from the central Wingate mesa seen in the previous photo (and from Castle Rock?). The video is for his song Blaze of Glory. Castle Rock, the Priest and Nuns, and Fisher Towers can occasionally be seen in the video, along with other panoramas of the area.
Some References: Doelling, H. H., 1996, Geologic map of the Dewey quadrangle, Grand County: Utah Geological Survey, M-169, scale 1:24,000.
Doelling, H. H., and Ross, M. L., 1998, Geologic map of the Big Bend quadrangle, Grand County, Utah: Utah Geological Survey, M-171, scale 1:24,000.
Doelling, H. H., 2001, Geologic map of the Moab and eastern part of the San Rafael Desert 30' x 60' quadrangles, Grand and Emery Counties, Utah, and Mesa County, Colorado: Utah Geological Survey M-180, scale 1:100,000.
Doelling, H. H., 2002, Geologic map of the Fisher Towers quadrangle, Grand County, Utah: Utah Geological Survey, M-183, scale 1:24,000.
