Peach Springs Tuff | Black Mountains | Mohave County, Arizona.
Warm Springs exposure of the Peach Springs Tuff, southern Black Mountains, Mohave County, Arizona. The Peach Springs Tuff, emplaced ~ 18.9 million years ago, forms the big cliff. The lower cliff is the Cook Canyon Tuff.
For those interested in seeing the Peach Spring Tuff of western Arizona, see Charles Ferguson's 29-p field trip guide, 'The Peach Spring Tuff, its source caldera, and implications for structural geology of the Colorado River Extensional Corridor'.
Courtesy of the Arizona Geological Society. http://repository.azgs.az.gov/uri_gin/azgs/dlio/1878