Stanley William Lohman

“ Last but far from least among the factors responsible for the grandeur of Arches National Park and the Plateau in general is the desert climate, which allows one to see virtually every foot of the vividly colored naked rocks, and which has made possible the creation and preservation of such a wide variety of fantastic sculptures. A wetter climate would have produced a far different, smoother landscape in which most of the rocks and land forms would have been hidden by vegetation. ”

“ Geologists have different opinions as to just how grabens and complex systems of joints have formed, but all seem to agree that tensional forces were involved. Some think that solution of salt and gypsum from the Paradox Member of the Hermosa Formation by ground-water movement allowed the brittle Cedar Mesa Sandstone and other overlying rocks to sag, producing tension cracks and faults. ”

“ Ordinary passenger cars now can go 23⁄4 miles west of Squaw Flat to Soda Spring, at the east base of Elephant Hill, but beyond Soda Spring four-wheel-drive vehicles should be used. Some people conquer the hill in dune buggies or on motorcycles, but this is considered quite dangerous. Both sides of this short (11⁄4 miles) but formidable hill have switchback curves too sharp to negotiate in the regular manner, so special driving techniques must be followed. On the east side, you must drive out on a flat rock, jockey back and forth until turned completely around, then proceed up the hill. ”

“ Before giving examples of arches in each of the three classes, it is appropriate to remark that the arches and other erosion forms in the park represent but a fleeting instant in geologic time. Many of the pinnacles or piles of rock may be the broken remains of former arches, and many of the arches we see may be gone tomorrow, next year, or a few hundreds of years and, certainly, before many thousands of years. ”

“ Trips by power boats, including jet boats, can be arranged from either Green River or Moab. Some passengers from Moab return by jeep from Lathrop Canyon via the White Rim Trail, and some from Green River return on land via the Horsethief Trail. Many prefer the quieter float trip down to the confluence, with return to either town by a prescheduled power boat, and some more adventurous souls float through the rapids of Cataract Canyon all the way to Lake Powell. ”

“ Maxine Newell and other members of the National Park Service (Maxine Newell, written commun., 1971) , we learn what life in the area was like:
We have started a cattle spread on a desert homestead. We call it the Bar-DX Ranch. Fred and I live in a little log house on the bank of a creek that is sometimes dry, sometimes flooded from bank to bank with roaring muddy water. We are surrounded with rocks—gigantic red rock formations, massive arches and weird figures, the like of which youve [sic] never seen. The desert is a hostile, demanding country, hot in summer, cold in winter. ”

“ At the mouth of Horseshoe Canyon, about 3 miles below Bowknot Bend, we pass a large rincon where the Green River shortened its course by about 3 miles. Some idea of the rincon’s antiquity is gained from the facts that the river is now some 350 feet lower than at cutoff time, whereas Bowknot Bend (fig. 62) has shown no visible deepening in 97 years. This rincon was not noted by Powell or other early voyagers, seemingly because they did not happen to climb the banks at this point, but it is quite noticeable on modern topographic maps and on aerial photographs. ”

“ This 26-inch pipeline follows the general route of U.S. Highway 163 from Cortez, Colo., past Moab to Sevenmile Canyon 10 miles northwest of Moab, where it turns abruptly to the northeast and crosses about the middle of Arches National Park. It crosses the park road and the flat area between the Fiery Furnace and the southeast end of Devils Garden, but the scars are so well healed that most visitors are unaware of its existence unless they happen to look southwestward across Salt Valley, where the filled excavation is still visible. ”

“ In figure 1 the campground is shown west of the old road; the new road is west of the campground, but no map of the new route was available for plotting in figure 1. About a mile before we reach the campground a jeep trail heads west then northwest about 51⁄2 miles to Canyonlands Overlook, a scant mile from, but some 1,400 feet above, the eastern border of Canyonlands National Park. This overlook affords fine views of the Colorado River canyons and the eastern shore of Island in the Sky, but at present (1973) there are no plans to improve the trail for passenger-car travel. ”

“ About 2.3 miles from the entrance station is a turnoff and parking area at the south end of the Park Avenue trail (stop 2) , which is about 1 mile long and ends at another parking area 1.7 miles farther north. An interesting hike is best made from south to north in a downhill direction, and hikers generally meet the cars of relatives or friends awaiting them at the northern parking area. The trail begins in a canyon cut in the soft Dewey Bridge Member and walled by high fins of the Slick Rock Member (fig. 27) , but farther north the canyon is floored by the bare Navajo Sandstone. ”

“ Another drive takes us up Salt Canyon 81⁄2 miles past the confluence with Horse Canyon to another confluence and Y, which has a primitive campsite without water. One mile up the left, or southeast, tributary is a parking area where we begin the 1⁄2-mile walk to Angel Arch, considered by many people to be the most beautiful and spectacular arch in the park if not in the entire canyon country. ”

“ Three more miles southward takes us to Grand View Point and its nearby picnic area. Though named after the former Grand River some 2,000 feet below, Grand View Point has a double meaning, for we see from here a truly grand view (fig. 21) ! At our feet is spectacular Monument Basin, cut below the White Rim into the brick-red Organ Rock Tongue of the Cutler Formation. The White Rim Sandstone here is slightly thicker than to the northeast (fig. 20) but thinner than to the west (fig. 23) , because it forms a wedge-shaped body that thickens westward. ”

“ Arches National Park and most of nearby Canyonlands National Park lie within what geologists have termed the “Paradox basin,” which contains a remarkable assemblage of sediments called the Paradox Member of the Hermosa Formation. These deposits were laid down in shallow seas and lagoons during Middle Pennsylvanian time, roughly 300 million years ago (fig. 59) . As indicated in figure 4, the Paradox Member contains, in addition to shale and limestone, minerals deposited by the evaporation and concentration of sea water—common salt, gypsum, anhydrite, and potash salts. ”

“ Late in the Cretaceous Period a large part of central and southeastern United States, including the eastern half of Utah, sank beneath the sea, as shown in figure 81, and received thousands of feet of mud, silt, and some sand that later compacted into the Mancos Shale. This formation and all the younger and some older strata have long since been eroded from the park area but are present in adjacent areas, such as the lower slopes of the Book Cliffs north of Green River, Crescent Junction, and Cisco (fig. 7) . ”

“ The prehistoric inhabitants of the Plateau learned that effective and enduring designs, called petroglyphs, could be created simply by chiseling or pecking through the thin dark layer to reveal the buff or tan sandstone beneath. Most petroglyphs were created by the Anasazi, but those showing men mounted on horses were done by Ute tribesmen after the Spaniards brought in horses in the 1500’s. The Fremont people and some earlier people painted figures on rock faces, called pictographs, and some of these had pecked outlines. ”

“ It is best traveled when the canyon bottom is moist but not soaked. When the sand is soft and dry, a shift into four-wheel drive is generally necessary. Signs warn of quicksand, which occurs when the sand is fully saturated; hence, summer thundershowers sometimes require delaying or postponing the trip. 67 When in doubt, consult a park ranger for expected weather and trail conditions. Thundershowers sometimes occur so suddenly and violently as to cause serious floods, and the “road” is closed when heavy rain is expected. ”

“ The Navajo also forms the impressive reef at the east edge of the beautiful San Rafael Swell, a dome, or closed anticline, now crossed by Highway I-70 between Green River and Fremont Junction, Utah.
As we journey upward in the time spiral (fig. 59) , we come to the Jurassic Entrada Sandstone, which stars in Arches N.P., with help from the underlying Navajo Sandstone, and a supporting cast of both older and younger rocks. The Entrada also forms the grotesque erosion forms called “hoodoos and goblins” in Goblin Valley State Park, north of Hanksville, Utah. ”

“ Bates Wilson, recently retired superintendent not only of Canyonlands National Park but also of nearby Arches National Park and of Natural Bridges National Monument about 80 miles to the south, is one of the few men in the park service who has guided a national park through all phases—location, promotion, establishment, and initial development. He retired in June 1972 to a ranch along the Colorado River north of Moab. ”

“ As vividly shown in figure 12, the Entrada Sandstone on the northeast flank of the Salt Valley anticline has been broken by Earth forces into thin slabs mostly 10 to 20 feet thick between nearly parallel joints, but, as will be noted in the descriptions of individual arches, some rock walls are only 1 or 2 feet thick, whereas others are 50 feet thick or more. Some weak or thin slabs have weathered away, leaving the stronger or thicker ones as towering fins, particularly in the Fiery Furnace and Devils Garden areas. ”

“ Let us follow the paved road from U.S. Highway 163 all the way to Dead Horse Point, which was set aside as a state park in 1957. The park has a visitor center, museum, modern campgrounds and picnic facilities, and piped water, which is hauled all the way from Moab. An entrance fee of $1 permits us to drive across the narrow neck to a parking area near the point proper, which is protected by stone walls and is provided with a ramada, benches, paths, and sanitary facilities. ”

“ After uplift and deformation, the Plateau was vigorously attacked by various forces of erosion, and the rock materials pried loose or dissolved were eventually carted away to the Gulf of California by the ancestral Colorado River. Some idea of the enormous volume of rock thus removed is apparent when one looks down some 2,000 feet to the river from any of the high overlooks farther south, such as Dead Horse Point (Lohman, 1974, fig. 15) . ”

“ The number of boaters or floaters on the Colorado and Green Rivers is increasing steadily, and trips by jet boat and other power boats are available from Moab. Tourist travel over good roads on Island in the Sky and Hatch Point and by paved road to The Needles also is increasing steadily. Travel west of the Green River and main stem of the Colorado River is still restricted largely to a few jeep trails and to hiking or horseback riding. ”

“ Ever since military jet aircraft broke the sound barrier, there has been a growing number of protests from concerned citizens, organizations, and National Park Service officials concerning the dangers sonic booms have posed to Indian ruins and delicate erosional forms in our national parks and monuments, such as natural bridges, arches and windows, balanced rocks, and natural spires or towers. ”

“ Except for 21⁄2 miles of partly graded road west from Squaw Flat, all travel to the west and south is by four-wheel-drive vehicle or on foot. In order to reach the confluence of the Green and Colorado Rivers, The Grabens, and Chesler and Virginia Parks, drivers must conquer formidable Elephant Hill, with its 40 percent grades and backup switchbacks. SOB Hill and the Silver Stairs also tax the skill and patience of jeepsters. Parts of this area will eventually be reached by graded roads, possibly by about 1977, but many hope that much of it will be kept accessible only by jeep or foot trails. ”

“ Joints are fractures along which no movement has taken place. Faults are fractures along which there has been displacement of the two sides relative to one another (fig. 6) . As noted in the report on Canyonlands National Park (Lohman, 1974) , the strata there, particularly along the valley of the Green River, are virtually flat lying or have only very gentle dips. Along the Colorado River above the confluence with the Green, however, the slightly dipping strata are interrupted by several gentle anticlinal and synclinal folds (fig. 5) and by at least one fault (fig. 6) . ”

“ Location of Monticello is approximate; that of other towns is believed to be correct. Park boundaries are not shown because of difficulty in locating them accurately, but features such as Colorado and Green Rivers can easily be compared with those in figure 1. (Fig. 7) .
20 Rocks and Landforms
The vivid and varied colors of the bare rocks and the fantastic canyons, buttes, spires, columns, alcoves, caves, arches, and other erosional forms of the canyon country result from a fortuitous combination of geologic and climatic circumstances and events unequaled in most other parts of the world. ”

“ Before beginning our trip through the park proper, let us consider a beautiful part many people fail to realize actually belongs to the park—the Colorado River canyon forming the southeastern boundary. ”

“ Just before reaching the Silver Stairs we may wish to pause long enough to take in the distant view to the northwest toward Junction Butte and Grand View Point. (See frontispiece.) After descending the steep Silver Stairs in a narrow cleft between rock walls, we reach another intersection: a two-way road continuing northwest goes to our destination, and a one-way road turning right returns to Elephant Hill via part of Elephant Canyon (fig. 58) .
About 2 miles to the northwest we cross the north end of Cyclone Canyon, the largest graben. ”

“ All vehicles should carry emergency equipment including a shovel, tow chain or rope, jack, tire tools, and other necessary items. Geologists and uranium prospectors working along the White Rim Trail have obtained good drinking water from small springs that flow from the base of the White Rim Sandstone in many places (Neal Hinrichs, U.S. Geol. Survey, oral commun., Feb. 1973) . After rains, runoff gathers in large potholes in the White Rim Sandstone in some places and affords emergency drinking water. Several such potholes filled with water are shown in figure 17. ”

“ The hike should not be attempted by anyone not in good physical condition, and it should not be undertaken alone; two or more people should travel together.
As shown in figure 52, the trail to Druid Arch from Chesler Park starts out on bare Cedar Mesa Sandstone marked by a succession of rock cairns, two of which are visible and without which the trail would soon be lost. The trail drops rapidly down into Elephant Canyon, which is then followed southward 2 miles to the arch. ”

“ Not exposed in the area but present far beneath the sedimentary cover, and exposed in a few surrounding places, are examples of the other two principal types of rocks: (1) igneous rocks, solidified from molten rock forced into or above younger rocks along cracks, joints, and faults and (2) much older 21 metamorphic rocks, formed from other pre-existing rock types by great heat and pressure at extreme depths. The particles comprising the sedimentary rocks were derived by weathering and erosion of rocks of all three types in the headwater regions of the ancestral Colorado River basin. ”

“ Erosion during much of the Tertiary Period and all of the Quaternary Period, combined with some sagging and breaking of the crust brought on by solution and lateral squeezing of salt beds beneath The Needles, The Grabens, and the Meander anticline, produced the landscape as we now see it.
The Precambrian rocks beneath the area are about 1.5 billion years old, so an enormous span of time is represented by the rocks and events in and beneath Canyonlands National Park. ”

“ The road upstream leads to two uranium mines in the lower part of Mineral Canyon which were reactivated in 1972 and 1973. The switchbacks are quite spectacular and are reminiscent of the Shafer Trail. Three miles south of the Horsethief Trail turnoff is a fork in the road—to the left the pavement continues to Dead Horse Point, and straight ahead a graded road leads southward to the Island in the Sky district of Canyonlands National Park. ”