As noted in the previous Blog Post, Forest Gump was
tired and decided to return to Gumpville.
So, we pushed off from Mexican Hat headed to Bluff, Utah, along US
163—with a quick side trip to visit Valley of the Gods. Before starting this trip, I had reread (for
about the 5th time) The Monkey
Wrench Gang by one of the West’s best known writers and environmentalists,
Edward Abbey.
Rather than a personal
account of travels in the wilderness, like perhaps my favorite book, Desert Solitaire, The Monkey Wrench Gang, is a novel set in the desert southwest
around Lake Powell. The book follows
four characters (some would call them misfits in society) as they destroy
federal equipment to protest destruction of the wilderness, especially the
construction of Glen Canyon Dam on the Colorado River. Misfits they may be (to many people), but by
the book’s conclusion we see that Seldom Seen Smith, Hayduke, Doc and Bonnie have
discovered their personal self and much about what they really want in life.
Along their journey the four become more heroes than bums. Today, most people who associate with nature
and the “outdoors” would say that Hayduke was correct---Lake Powell is nothing
but a large sediment trap that displays a “bathtub ring” (from years of
low water levels) and whose waters destroyed some mighty fine country.
But on with our journey. I liked Monument Valley Tribal Park (see
previous Blog Post) but perhaps thought it was a little crowded; however, the Valley of the Gods (VoG) was a wonderful,
uncrowded and smaller replica. VoG is a BLM-managed parcel of land accessible
by a 17 mile gravel/native loop road off US 163 (about nine miles north of
Mexican Hat) connecting to UT 261 (the Goosenecks of the San Juan Road). The road may or may not be traversed with a
passenger car---your choice. My pickup
has high clearance with 4-wheel drive (the latter not needed on this trip) and
I liked that choice. Like Monument
Valley, VoG has a rather flat valley floor with buttes, mesas and spires
“sticking up”; all are composed of the Cedar Mesa Sandstone. For a few months last year VoG was part of
Bear’s Ears National Monument; however, along came a person in in the swamp who
desires to “undo” any action of the previous administration and the VoG section
of the Monument was, as Bobby Bare might sing, another monument done gone.
Above two photos are spires of exposed Cedar Mountain Sandstone exposed in Valley of the Gods. |
The San Juan Country of the Colorado Plateau is
dominated by several small anticlinal uplifts with intervening synclinal
basins. By small I mean they do not
approach the size of time-related (Laramide Orogeny) mountain ranges such as
the Uinta Range but still extend tens of miles in length. The “big” anticlinal mountains expose
Precambrian rocks in the center that usually form the high peaks. The “smaller” upwarps usually have rocks no
older than Pennsylvanian in the center.
However, as noted in the previous Blog Post (see Raplee Monocline),
there are some spectacular folds and “bent” rocks within the these
upwarps. The best-known upwarp features
in Utah are the Monument Upwarp, the San Rafael Swell (a large anticlinal
uplift with a steeply dipping and folded eastern margin termed the San Rafael
Reef) and the Circle Cliffs Uplift (a north-south doubly-plunging anticline
with a steeply dipping (almost vertical) eastern margin, the Waterpocket Fold).
These large upwarps “were formed by tangential compressional forces that were
episodically repeated throughout the Phanerozoic [post Precambrian] and most
magnificently accentuated by Laramide and younger tectonism” (Stevenson,
2000).
Laramide anticlinal uplifts centered around Four Corners Region (X). Original source unknown bur perhaps attributed to Don Barrs. |
Google Earth© image of “bean-shaped” San Rafael Swell
in Emery County, Utah. The San Rafael Reef (steeply dipping beds) is the “toothed”
area in the southeast. See above map.
|
The Monument Upward is the
largest uplift in Utah and is about 110 miles long (north to south) and 50
miles wide extending from Kayenta, Arizona to the Abajo Mountains near Blanding,
Utah. Stevenson (2000) describes the upwarp as “asymmetrical with a sharply
defined east face, represented by the Comb Ridge Monocline and a gradual dip
west into the Henry Mountains Basin.”
Incised streams crossing the Upwarp have left behind some amazing
canyons (see Goosenecks of the San Juan).
Although US 163 crosses Comb Ridge on our road to Bluff, it is better
observed traveling to Natural Bridges National Monument (in the next Blog Post).
The Waterpocket Fold, the San Rafael Reef and the Comb
Ridge Monocline are, as Edward Abbey noted, places
so beautiful they can make a grown man break down and weep.
Comb Ridge, the east edge of the Monument Upward, exposed east of Bluff, Utah. The lighter rocks capping the ridge is the Late Jurassic Navajo Sandstone. Google Earth© image. |
Comp Ridge is a spectacular wilderness feature and
defines the east flank of the Monument Upwarp where numerous streams/canyons have
cut into the Ridge and erode features that resemble the teeth of a comb. These canyons also contain numerous cliff
dwellings/houses and rock art constructed by Native Americans known as the
Ancestral Puebloan Culture (and informally known as the Anasazi). More on this culture in the next Blog Post.
Comb Ridge exposure east of Bluff showing eroded small streams and canyons creating the comb teeth and providing a name for the steeply dipping rocks. Google Earth© image. |
In traveling through this area starting 50+ years ago,
I can only parrot the words of Edward Abbey, Wilderness is not a luxury but a necessity of the human spirit.
As US 163 crosses Comb Ridge on the way to Bluff, the
San Juan River does likewise. In much
younger days my paleo partner and I hiked to a feature along the River called
Mule’s Ear Diatreme, another one of those small-scale igneous features that
exposes both igneous rocks and chunks of once overlying sedimentary rocks. It is not a prominent as Alhambra Rock and Agathla
Peak noted in previous Blog Postings but is of the same origin and part of the
large Navajo Volcanic Field. My photos
from that earlier trip are long gone (due to a humidity problem while living in
Missouri); however, I picked up a couple or really nice views from credited
sources on the Web.
Mule's Ear is the sharp peak while the volcanic diatreme is immediately to the right. San Juan River in foreground. Photo taken in 1953 and is from USGS Open File Report 01-314, Gregory C. Compton. |
Comb Ridge with Mule's Ear Point and dark volcanic rocks of the diatreme to right. Photo courtesy of
|
After US 163 crosses Limestone Anticline and Comb
Ridge, the small town of Bluff is in view.
However, just before entering town is the primitive Sand Island
Campground on the south side of the Highway.
The camping sites seem to attract river runners and short term campers
but what attracted me was a very large petroglyph panel. The glyphs range in age from horseback riding
Native Americans (post 1492 at least) to figures that were chipped out
thousands of years ago. Good photos are tough to take
as the sun is often very bright and reflects off the rock. I believe the glyph rock is the Jurassic
Navajo Sandstone. The site is well worth
a visit—just off the highway, easy parking, short walk, and free.
Petroglyphs at Sand Island. Not Kokopelli the flute player in the bottom center. |
As I understand the early settlement of Bluff, a
contingent of ~200 “Mormon” (Church of Latter Day Saints) settlers had been
hunting a locality in southeastern Utah to colonize. That part of the country was/is quite hard on
“covered wagons” and the group was essentially stuck behind Comb Ridge and
other rock barriers until they located a way through along the San Juan River
and constructed Fort Bluff, and a small community. Today visitors are able to appreciate reconstructed early Bluff, 250-300 citizens,
three commercial RV/tent campgrounds, and some mighty fine eating
establishments. We spent some enjoyable
spring days there.
Welcome to Bluff, Utah with reconstructed "old Bluff" feature above. |
The San Juan River (named for Saint John the Baptist)
is the major stream of the Four Corners Area (Utah, Colorado, New Mexico,
Arizona) and a large tributary of the Colorado River--- now entering the
Colorado in a submerged arm of Lake Powell below the Goosenecks of the San
Juan. The San Juan has its origin high
in the San Juan Mountains of southwestern Colorado and wanders around the
region for ~385 miles before entering the Colorado. It evidently was flowing in the Pleistocene
as it has been able to breach the Monument Upwarp and leave behind the
magnificent incised canyons so easily seen at Gooseneck State Park. Around Bluff
there are several terrace levels of the River and these seem to support a
robust sand and gravel industry. Usually
river terraces are not that interesting; however, in wandering around and “exploring”
I came across some beautiful, large, well-rounded cobbles. So, what is interesting about a bunch of
large rounded rocks? For one, the
cobbles contain other smaller rounded cobbles and pebbles and therefore are a
type of sedimentary rock termed conglomerate.
Second, the cobbles are not of local origin and originated high in the
San Juan Mountains of Colorado and therefore traveled over 300 miles to
Bluff. Finally, the clasts in the
conglomerate are often large hunks of red chert/jasper and identify their
source as the Precambrian Uncompahgre Conglomerate. I never realized that one
day I would say a conglomerate is “pretty.”
Large (32 cm. width) rounded cobble located in terrace deposits near Bluff, Utah. Orginal source is Precambrian Uncompahgre Comglomerate exposed in the San Juan Mountains of Colorado. |
Photo of red chert (5 cm) from above cobble. |
The other nifty geological features at Bluff are two
pinnacles called the Navajo Twins. The
caprock of the Twins is the late Jurassic Bluff Sandstone composed of windblown
and cemented sand particles.
The caprock then protects the underlying Wanakah Formation with its
easily erodible thin-bedded siltstone and shales. Other outcrops of the Bluff Sandstone
essentially surround the town as large cliffs and provide the moniker for the
village.
Navajo Twins at Bluff Utah. |
Finally, for this post, travelers to the Bluff area
might want to visit some interesting geology where it is almost guaranteed they
will not encounter other groups—Recapture Pocket is a few miles east of Bluff and
then north on some gravel/native roads (get a map from the Bluff tourist
office). Recapture Pocket is a mini
Goblin Valley (Utah State Park with fees) where you are allowed to roam
free. The main attractions are the
numerous hoodoos or goblins where a resistant sandstone is perched on top of
less resistant shale/siltstone (like the Navajo Twins). The pocket is sort of a fascinating place
where I could be comfortable on a late October eve with a lawn chair, a shot of
single barrel bourbon, a nice small campfire and a full moon rising. That is until the coyotes started howling and
my imagination turned to big cats!
To
the question: Wilderness, who needs it? Doc would say: Because we like the
taste of freedom, comrades. Because we like the smell of danger. But, thought
Hayduke, what about the smell of fear. (Edward Abbey).
Hoodoos and exposures |
The hoodoos are exposed along Recapture Creek a short
distance above its mouth at the San Juan River.
I presume (geologic maps are almost non-existent) the exposed rocks are
the Morrison Formation of latest Jurassic age, or maybe the underlying Bluff Sandstone, or maybe both?? The Pocket is not well defined and a large area is covered. The area is the
type locality of the Recapture Member of the Morrison, a term that is in usage
by some geologists and thrown away by others.
So, maybe the Morrison?
So, I guess Hayduke
Lives (an Edward Abbey novel published posthumously in 1990 and a sequel to
The Monkey Wrench Gang)---the
American Southwest is in trouble and the Green Baron is wearing the white hat
and trying to sabotage the world’s largest walking dragline! Yes, I have been told before that I have a
weird and wandering mind.
And
the wind blows, the dust clouds darken the desert blue, pale sand and red dust
drift across the asphalt trails and tumbleweeds fill the arroyos. Good-bye, come
again (Edward Abbey).
Next time it is on to Hovenweep National Monument, Blanding, and Edge of
Cedar’s State Park. Stay Tuned.
Stevenson,
G.M., 2000, Geology of Goosenecks State Park, San Juan County, Utah in
Geology of Utah's Parks and Monuments, D.A. Sprinkle, T.C. Chidsey, Jr.,
and P.B. Anderson, eds.: Utah Geological Association 28.
REFERENCES CITED
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