As the map (fig. 1) shows, Island in the Sky is really a fork of a
wedge-shaped peninsula extending southward between the two rivers. An
outlier to the south named Junction Butte has already been severed from
the main peninsula by erosion and now is a true island. (See
frontispiece and fig. 22.) A large chunk of Island in the Sky south of
The Neck was about to be severed by erosion from the main peninsula to
become a true island, when recent widening and grading of the road gave
it a temporary reprieve. When my family and I first squeaked over this
narrow neck in 1960 by jeep, furtive glances to right or left showed the
two canyons perilously close, and complete severance seemed imminent.
The road builders have staved off disaster for a few thousand years, but
ultimately the large section to the south will become another island,
and a bridge will be required to connect it to the mainland. Its
appearance from the air before the road widening is shown in figure 11.
[Illustration: AERIAL VIEW OF THE NECK AND SHAFER TRAIL, looking
southwest, taken before rebuilding of park road on mesa top.
Cliff-walled canyon to right of The Neck, in middle, drains westward
to the Green River; south fork of Shafer Canyon to left drains
eastward to Colorado River. This is the narrowest part of Island in
the Sky. Photograph by National Park Service. (Fig. 11)]
The entrance road to Island in the Sky intersects U.S. Highway 163 at a
point 10 miles northwest of Moab, or 21 miles southeast of Crescent
Junction on Interstate Highway 70. From U.S. 163 a paved road climbs
colorful Sevenmile Canyon past sandstone cliffs of the Wingate, Kayenta,
and Navajo Formations to reach the high mesa. There, just “offshore” to
the north, are anchored the “battleships” that guard the island—Merrimac
and Monitor Buttes (fig. 12). These landmarks are composed of the
Entrada Sandstone—the same rock that forms Church Rock at the entrance
to the Needles district (fig. 37) and that shapes the spectacular arches
in Arches National Park. All three members of the Entrada (Wright and
others, 1962), as noted in the figure 12 caption, are present here as
well as at Church Rock. Eleven miles from the junction with U.S. Highway
163 a graded road to the right, called Horsethief Trail, goes 16 miles
down to the Green River, where it connects with roads following the
river both upstream and downstream. The road upstream leads to two
uranium mines in the lower part of Mineral Canyon which were reactivated
in 1972 and 1973. The switchbacks are quite spectacular and are
reminiscent of the Shafer Trail. Three miles south of the Horsethief
Trail turnoff is a fork in the road—to the left the pavement continues
to Dead Horse Point, and straight ahead a graded road leads southward to
the Island in the Sky district of Canyonlands National Park.
[Illustration: MERRIMAC (LEFT) AND MONITOR BUTTES guard north
entrance to Island in the Sky. White rock near middle is Navajo
Sandstone. Buttes comprise all three members of Entrada Sandstone:
remnant white top of Moab Member, vertical cliffs of Slick Rock
Member, and sloping base of Dewey Bridge Member. (Fig. 12)]
Most of Island in the Sky has a scattered growth of piñon and juniper
trees, but several large flat areas, such as Grays Pasture, contain
sufficient sandy soil to support a mantle of grass and weeds, which is
used for grazing; however, grazing in this part of the park will be
discontinued in 1975.