The junction of the park road with U.S. Highway 163 is shown at the
lower left of figure 23, and the entrance station, Visitor Center,
parking lot, and several buildings are seen at the lower right. Several
residences for park personnel and other buildings are shown in figure
25. As shown in the lower part of figure 23, the geology at the park
entrance is rather complex, as the park boundary here is partly along
the Moab fault and partly along a branch fault—both in the Seven
Mile-Moab Valley anticline (fig. 7). The Moab fault extends
northwestward from Moab for more than 30 miles (McKnight, 1940, p. 120,
121, pl. 1).
As shown in figure 23, soon after leaving the checking station the park
road begins to ascend the first of several switchbacks, and cuts first
into the Slick Rock Member, then the Dewey Bridge Member, and finally
the Navajo Sandstone the rest of the way to and beyond the top of the
hill.
From points a mile or so up the hill may be seen interesting features in
several directions.[5] The view to the southwest is shown in figure 23,
to the west are the Three Penguins (fig. 24). A good view of the Moab
Valley is had by looking southeastward (fig. 25). A well in the Navajo
Sandstone at the base of the hill supplies water to all the residences
and to the Visitor Center, where a drinking fountain and modern
restrooms are available to the public. Storage is provided by a steel
tank hidden in a ravine above the buildings shown in figure 25.
To the north the wall of Entrada Sandstone is cut by a normal fault
(fig. 6), as shown in figure 26.
[Illustration: FAULTED SEVEN MILE-MOAB VALLEY ANTICLINE. Top, View
toward the southwest from park road about 1 mile above entrance
station. Bottom, Geologic interpretation of photograph in part after
McKnight (1940, pl. 1). Moab fault and branch fault (both normal
faults, fig. 6) unite just beyond ridge of Slick Rock Member. Total
vertical displacement along both faults is about 2,500 feet. H.F.,
unnamed upper member of Hermosa Formation; M.F., Moenkopi Formation;
D, downthrown side of faults; U, upthrown side. Valley fill and
slope wash of recent (Holocene) age obscure faults and underlying
rocks. The original sequence of the rocks may be visualized by
placing the Navajo Sandstone, the upper part of which is exposed at
the lower right, on top of the Kayenta Formation, the lower few feet
of which cap and protect the cliffs of Wingate Sandstone in the
background. The Pacific Northwest (gas) Pipeline mentioned on page
15 is buried beneath the slice of the Moenkopi Formation between the
two faults, which accounts for the disturbed appearance of the rock.
(Fig. 23)]
[Illustration: Geologic interpretation of photograph]
[Illustration: THREE PENGUINS, viewed westward from park road about
1 mile above entrance station. Penguins are carved in massive Slick
Rock Member seen resting upon thin-bedded Dewey Bridge Member. (Fig.
24)]
[Illustration: MOAB VALLEY, viewed southeastward from park road
about 1 mile above entrance station. Moab fault in about middle of
valley, hidden beneath recent (Holocene) valley fill and slope wash,
separates unnamed upper member of Hermosa Formation just above U.S.
Highway 163 on right from Navajo Sandstone forming hills on left and
ledges in foreground. Park Service residences at base of hill. White
patch bordering Colorado River on northwest is tailings pile of
Atlas Corporation’s uranium mill. Moab and Spanish Valley are beyond
river, and south end of La Sal Mountains forms distant skyline.
(Fig. 25)]
[Illustration: FAULTED WALL OF ENTRADA SANDSTONE, north of park road
about 1 mile above entrance station. Fault is nearly vertical and
normal (fig. 6), but fault trace slopes steeply downward to right,
separating upthrown Slick Rock and Dewey Bridge Members on left from
downthrown Slick Rock Member on right. Light-colored rock in
foreground is Navajo Sandstone. Displacement probably does not
exceed 50 feet. (Fig. 26)]
[Illustration: PARK AVENUE, viewed to the north along trail. (Fig.
27)]