Figure 14.21
Fault map of California and Nevada. (A) The North American and Pacific plates are fractured by many fault systems in the western United States. (B) In the Great Basin Desert of Nevada, the crust is being rifted and stretched, creating a series of normal faults oriented north-south and resulting in horst and graben topography. The fault blocks have rotated slightly as the crust has been stretched. Portions of the blocks form grabens (valleys), and portions of them form horsts (mountain ranges), as illustrated here. The photograph shows Nevada’s snow-capped Wheeler Peak, part of one of the many mountain ranges in Nevada produced by a rotated and tilted block.(Bruce Gervais)