Physics Photo of the Week

April 19, 2013

Cathredral Valley
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 dcollins@warren-wilson.edu.

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