UPHEAVAL DOME
Five miles northwest of the Y we come to Upheaval Dome, one of the most unusual geographic and geologic features of the park. Viewed from the air ([fig. 25]), it resembles somewhat a volcanic or meteor crater and has been called such by some. Because beds of salt are known to underlie the park, some have suggested that the salt may have thickened and welled upward to form a salt dome, similar to domes along the Gulf Coast (Mattox, 1968). However, only 1,470 feet of salt was encountered in an oil test just east of Upheaval Dome (Robert J. Hite, U.S. Geol. Survey, oral commun., Feb. 13, 1973); so although salt may have played a role, Upheaval Dome clearly is not a salt dome with dimensions similar to the Gulf Coast types. It may be related to a mound on the deep-seated Precambrian rocks (Joesting and Plouff, 1958, fig. 3; Joesting and others, 1966, p. 13, 14, 17), but the exact origin of the dome is not clear.
The central part has the structure of a dome, in that the strata dip downward away from the middle. A ringlike syncline, or downward fold in the rock layers ([fig. 26]), surrounds the dome, beyond which the strata resume their nearly flat position. The white rock in the bottom of the craterlike depression is not salt, but jumbled large fragments of the White Rim Sandstone. Surrounding that are slopes of the Moenkopi and Chinle Formations, cliffs of the Wingate Sandstone, a circular bench of the Kayenta Formation, and outer ramparts of the Navajo Sandstone. Upheaval Canyon leads to Stillwater Canyon of the Green River at the upper left.
STILLWATER CANYON AND GREEN RIVER, looking southwest from Green River loop of river. Brown material covering nearby parts of the White Rim is lower part of Overlook. Orange Cliffs in background, Henry Mountains on right skyline, Turks Head in Moenkopi Formation. (Fig. 23)
TURKS HEAD, an erosional remnant of the White Rim Sandstone supported by red beds of Organ Rock Tongue, in loop of Green River. Aerial view looking north. Photograph by National Park Service. (Fig. 24)
UPHEAVAL DOME, aerial view looking northwest toward junction of Upheaval and Taylor Canyons with Labyrinth Canyon of Green River. Photograph by Walter Meayers Edwards, © 1971 National Geographic Society. (Fig. 25)
CUTAWAY VIEW OF SYNCLINE, or downfold of the rocks. From Hansen (1969, p. 108). (Fig. 26)
One mile before the road ends, a well-marked foot trail leads to the top of Whale Rock, a prominence on the Navajo Sandstone that forms the outer ring of the dome. At the end of the road, another foot trail ascends from the picnic area to the foot of the Wingate Sandstone cliffs around the central part of the dome. The views of the dome from these trails are interesting, but you are really too close to get a true picture of the unusual feature, which is obtainable only from the air, as shown in [figure 25].
Just west of Upheaval Dome, Bighorn Mesa is connected to Steer Mesa by a neck only 15 feet wide flanked by 300-foot vertical cliffs, as pointed out by McKnight (1940, p. 12). I later learned from Ed McKnight (oral commun., June 6, 1973) that during his field work in this area in 1926 he was riding a mule across this narrow neck when the half-asleep mule suddenly became aware of the dropoff on one side and began to turn around and head back. Ed hastily but cautiously dismounted and led the mule across! When this neck is finally breached by erosion, Bighorn Mesa will be just as isolated and inaccessible as Junction Butte, now cut off from Grand View Point. (See [frontispiece] and [fig. 27].)