CANE CREEK ANTICLINE, looking northwest from Anticline Overlook. Colorado River is cutting into limestone of unnamed upper member of Hermosa Formation in lower bench at crest of fold; Rico Formation, with bluish-white Shafer limestone at top, forms upper curved bench; remainder of formations are as given in caption for [figure 29]. Potash mine (right) and evaporation ponds (left) are operated by Texas Gulf, Inc. Merrimac and Monitor Buttes on right skyline are shown in [figure 12]. (Fig. 31)
To the northwest ([fig. 31]; see also [fig. 13]) is a textbook example of a rock fold—the Cane Creek anticline—laid bare by the Colorado River cutting directly across its crest ([fig. 1]). Anticlines are noted as sources of or at least hunting grounds for oil and gas, and this one is no exception, although production has been relatively small and was stopped altogether in about 1963. Some oil and gas was produced also from wells on the north flank of Shafer dome, just beneath Dead Horse Point (figs. [1], [15]), but other favorable-looking structures farther south that were tested, such as Lockhart anticline, Rustler dome, and Gibson dome ([fig. 1]), failed to yield commercial amounts (Baker, 1933, p. 80-84). Some of the colorful events in the early days of wildcatting are noted on [page 100].
Exploration for oil and gas led to the discovery of potash beneath several anticlines in eastern Utah and western Colorado. According to Hite (1968, p. 325), the Cane Creek anticline is underlain by about 5,200 feet of salt-bearing rocks in the Paradox Member of the Hermosa Formation ([fig. 9]), of which about 84 percent is halite (common salt, sodium chloride) and associated potash salts (sylvite, potassium chloride). The potash mine of Texas Gulf, Inc., is shown at the right in [figure 31]. The white area to the left of the mine is waste common salt, which is recovered with the potash salts, and the white area with dark stripes at the left is a small part of more than 400 acres of evaporation ponds built to separate the salts. These ponds also can be seen from Dead Horse Point. The dark stripes are the visible parts of plastic membranes lining the ponds. Mining of an 11-foot bed of ore began by usual underground methods from the bottom of a shaft 2,788 feet deep but became too difficult because of intense and intricate folding of the salt beds. Now the salts are being extracted by a method involving solution, wherein river water is introduced into the former workings and allowed to stand long enough to dissolve the salts, then the brine is pumped out to evaporation ponds, and the valuable potash salts are separated from the sodium salts. Closeup views of the mine and evaporation ponds are seen in figures [70] and [71].
As noted earlier, most of the readily recognizable thin beds, such as the White Rim Sandstone, pinch out south of here, and [figure 31] marks the northeasternmost exposure of the Shafer limestone at the top of the Rico Formation. Northeast from here the Rico and overlying Cutler Formation are not readily separable and are included in the so-called Cutler Formation undifferentiated. This land-laid unit of red sandstone, siltstone, and shale is as much as 8,000 feet thick just southwest of the ancient Uncompahgre highland (present Uncompahgre Plateau, in western Colorado and eastern Utah), from which it was derived by erosion during the Permian Period ([fig. 80]).
Orange Cliffs
The high mesas west of Canyonlands National Park do not form as distinct a mainland as does Hatch Point, but rather are broken up into a maze of peninsulas and islands, as shown in [figure 1]. Owing to the gentle northwestward dip of the rock strata, the altitude of the mesas declines from about 7,000 feet in the south to about 5,300 feet in the north and northwest, where the whole aspect of the country becomes more rounded and subdued. As shown on the map ([fig. 1]), however, the name Orange Cliffs is applied to much of the eastward-facing cliffs, which are made of the Wingate Sandstone capped by the Kayenta Formation. Remnants of the Navajo Sandstone increase in number to the north and west, where remnants of the next two younger rock units—the Carmel Formation and the Entrada Sandstone—also occur. Thus, the cliff-forming units dip downward beneath younger rocks that form the relatively flat Green River Desert to the northwest, also referred to as the San Rafael Desert. [Figure 32] is a view southeastward from The Spur, shown on the map ([fig. 1]) as the northern section of the Orange Cliffs.
At present (1973), the areas west of the Green River and the main stem of the Colorado River are the least accessible of any in the park and in this respect have not changed much since Butch Cassidy and his Wild Bunch roamed the area, except that the former main horse trails are now jeep trails. A secondary road south from the town of Green River goes past the north side of the Horseshoe Canyon Detached Unit (figs. [1], [2]) and connects with another secondary road to the west, which joins Utah Highway 24 at Temple Junction, 20 miles north of Hanksville; near Horseshoe Canyon a jeep trail leads south to the Orange Cliffs. Owing to blowing sand, these “roads” are not considered reliable for passenger cars and are best negotiated by four-wheel-drive vehicles or horses.
VIEW SOUTHEASTWARD FROM THE SPUR, in northern section of Orange Cliffs. Junction Butte and Grand View Point on left skyline; Abajo Mountains in extreme distance to right of center. Photograph by Parker Hamilton, Flagstaff, Ariz. (Fig. 32)