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Fisher
Towers – The towering red rock sculptures
of Grand County, Utah
by Carl Ege
Fisher Towers, located about 20 miles northeast of Moab in southeastern
Utah, is one of the most scenic landscapes along the Colorado River.
Administered by the Bureau of Land Management, Fisher Towers Recreation
Site is a popular destination for hikers and rock climbers. A moderate
2.2-mile (one way) hiking trail takes you along the base of the
towers and spires to a scenic overlook of Professor Valley and the
Colorado River.
Fisher Towers seen from the road leading to the trailhead. The lower
and middle parts of the towers are the Cutler Formation. The lower
member of the Moenkopi Formation forms the upper darker part.
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Geologic Information: Fisher Towers contains layers of
sedimentary rock in various shades of red-brown, red-purple, and
maroon. The colors are a result of varying amounts of hematite (an
iron oxide).
The upper, darker part of Fisher Towers consists of the lower sandstone
member of the Triassic Moenkopi Formation (approximately 245 million
years old).
The middle and lower parts of the towers are sandstone, mudstone,
and conglomerate of the Permian Cutler Formation (approximately
290 million years old).
Close-up view of a conglomerate layer within the Cutler Formation.
Hammer for scale.
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The conglomerate contains sub-rounded to rounded cobbles and pebbles
of quartz, feldspar, mica, granite, schist, and quartzite that were
eroded from nearby Precambrian (over 1 billion years old) metamorphic
and igneous rocks.
These rocks originated from the Uncompahgre highland, a mountainous
region that formed at the beginning of the Pennsylvanian period
(approximately 320 million years) in western Colorado and eastern
Utah.
Rivers and streams flowing south from the Uncompahgre highland
eroded, transported, and then deposited rock and sediment in channels
and flood plains. By the end of the Permian period (250 million
years ago), the Uncompahgre highland no longer existed; it had been
reduced to low hills and plains.
A rock pedestal, approximately 25 feet high, sculpted from the Cutler
Formation and capped by a large sandstone slab from the lower member
of Moenkopi Formation.
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The Colorado Plateau region was uplifted starting approximately
80 to 50 million years ago, and over the past several million years
many of the existing erosional features of the Colorado Plateau
were created, including canyons, mesas, buttes, arches, bridges,
hoodoos, spires, pedestals, and towers.
At Fisher Towers, erosion continues to sculpt the towers, spires,
and pedestals. One area, approximately one mile from the start of
the trailhead, contains several rock pedestals capped by large sandstone
slabs of the Moenkopi Formation. These rock slabs fell from the
cliffs high above.
The sandstone, more resistant to erosion than the softer underlying
layers of the Cutler Formation, protects and preserves the soft
rock underneath, creating rock pedestals.
In a similar manner, the Moenkopi Formation has provided a resistant
cap for some of Fisher Towers, allowing erosion to carve the aweinspiring
spires and towers that we see today.
How
to get there: From Moab, travel 2 miles northwest along U.S.
191 to the turnoff for Utah State Highway 128. Turn right (northeast)
and travel approximately 21 miles to the turnoff for Fisher Towers
Recreation Site (just past milepost 21). Turn right (east) and proceed
2.2 miles to the trailhead.
Geosights article, Survey Notes,
v. 36 no. 3, July 2004
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