Although the Colorado River enters Canyonlands National Park about 33 river miles below Moab, most boaters or floaters begin their voyage either at Moab or near Potash, and most travelers of the White Rim Trail begin at Moab, so we will start our trip at Moab. No logs or river runners’ guides are available as yet for the reach from Moab to Potash, but below Potash some details of the geology have been described by Baars in Baars and Molenaar (1971, p. 59-87).
As noted at the beginning of this chapter, above the confluence both the Green and Colorado Rivers are very crooked, have very low grades, and are free from rapids. As with the Green, the soft rocks along the Colorado have a generally low northward dip that partly explains the river’s gentle grade and its southward flow through increasingly lower and older strata. Unlike the Green, however, the gentle dips of the strata in the canyons of the Colorado are interrupted by several gentle anticlinal (fig. 14) and synclinal (fig. 26) folds and by at least one fault. The most important of these geologic structures and other features will be noted as we journey down the river.
The first 14 miles from Moab Valley to Potash can be made either by river or by paved Utah Highway 279. This highway leaves U.S. Highway 163 near the uranium ore-reduction plant several miles northwest of Moab, leaves Moab Valley through The Portal (fig. 68), and follows the west bank of the river. A paved secondary road from Moab follows the east bank of the river through The Portal and through Kings Bottom, where it crosses the Kings Bottom syncline, to the mouth of Kane Springs Canyon, then becomes a gravel road that ascends this canyon southward to and beyond Hurrah Pass (fig. 30). High above this road north of Kings Bottom are petroglyphs and a few cliff dwellings in the vertical cliffs of Wingate Sandstone. A ranch “house” at Kings Bottom has been excavated entirely into the Wingate cliff. Convenient turnouts have been provided at several places along Highway 279 for viewing petroglyphs or other points of interest. Small viewing tubes welded to vertical steel posts having signs help visitors locate and see the features described.
[Illustration: THE PORTAL, in south wall of Moab Valley, through which the Colorado River, Utah Highway 279 (on right), and a paved secondary road (on left) leave the valley to enter the canyons in and above Canyonlands National Park. Rounded remnants on top are Navajo Sandstone; cliffs are Kayenta Formation and Wingate Sandstone; red slopes are Chinle and Moenkopi Formations, and perhaps a little of the Cutler Formation at the base. Light-colored patches at base of slope behind trees on left are contorted intrusions of Paradox Member of Hermosa Formation. (Fig. 68).]