The light-colored area in the foreground is the surface of the Bishop Tuff, 500 cu km of airfall-pumice and pyroclastic-flow deposits related to the formation of the Long Valley caldera about 760,000 years ago. The low mounds formed as a result of degassing of the deposit while it cooled.

Photo by Larry Mastin, 1992 (U.S. Geological Survey).

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Long Valley