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.
[Illustration: 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)]
[Illustration: 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)]
[Illustration: 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)]
[Illustration: 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.)