Aerial oblique view of the Navajo Bridge area of the Vermillion Cliffs near Lee’s Ferry, at Mile 4.  The Moenkopi shales at the base of the escarpment are unusually rounded and subdued, suggesting that they were inundated beneath lake waters in the relatively recent geologic past.  These cliffs would have been inundated by lakes impounded behind the highest lava dams (up to elevation 4125 feet).

The colorful escarpment of the Vermillion Cliffs, between Grand Canyon and Zion National Parks.  The Vermillion Cliffs are comprised exclusively of Mesozoic age sediments, which have spawned an impressive array of Toreva Block landslides, initially described by Strahler (1940).

View looking northeast at the hummocky topography that typifies the base of the Vermillion Cliffs escarpment.  The hummocks are formed by a series of retrogressive Toreva Block landslides, suggestive of rapid cliff retreat when the Chinle Shale was much wetter than at present.

Arthur Straher’s cross sections through the massive Toreva Block bedrock slump landslides along the base of the Vermillion Cliffs. The Chinle Shale loses significant shear strength when saturated, but these failure surfaces lie above 4,400 feet, well above the maximum level of inundation caused by the lava dams in the western Grand Canyon.

Questions or comments on this page?
E-mail Dr. J David Rogers at rogersda@umr.edu.