Cathedral Valley, part of Capitol Reef National Park in Central Utah is noted for vivid sandstone mesas and cliffs in an arid part of the American Southwest exhibiting majestic geology. Click on the photo for a larger view. North is up in the photo.
A commercial airplane traveling across central Utah on a clear day in the early morning presented me with fascinating views of this geology from a window seat. With the help of area road maps and Google Earth I was able to figure out the exact location of this landform.
The most fascinating section of this area is the "wall
of cathredrals", a linear chain of eroded mesas in the
southern section of the rather flat valley. What
caused these features? Why are the slopes of these
mesas so steep? Many millions of years ago this area
was part of an inland sea that deposited many sediments that
are widely distributed over the Colorado Plateau. The
Colorado Plateau raised these massive sediments enormously
which permitted later erosion into many canyons - including
the Grand Canyon in Arizona. These sediments, called Entrada
Sandstone, form the vertical cliffs of this central wall as
well as the walls of the broad valley. Cracks and
joints in the Entrada Sandstone allowed fairly "rapid"
erosion during more recent times with a moist climate that
has since dried up. In addition, these mesas are capped
by a different kind of sedimentary rock called Curtis
Formation that is more resistant to
erosion. A close view of the tops of the "wall of
cathedrals" shows the lighter-colored Curtis
Formation capping the mesas in the image at right. The
capping Curtis formation was formed under different
conditions - a shallower sea, different climate, several
million years later that gave it a different, more
impermeable structure, hence more resistant to erosion.
A ground level image at left
(created by Bob Palin, distributed under the Creative
Commons SA-2.5 license) more clearly shows the lighter
colored mesa caps. Click on the image or here
for a larger image in Wikimedia Commons.
Many thanks to Bob Palin for providing his photos for the
Creative Commons use.
Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us. Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to firstname.lastname@example.org.
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