owens valley

"A geologist would probably tell you that Owens Valley is a graben (German for "ditch"), formed when the earth's crust stretched enough to break. The valley floor dropped between two large faults during earthquakes. One fault cuts the eastern base of the Sierra Nevada and the other cuts the western base of the Inyo Mountains. Each large earthquake may have produced only around 10 feet (give or take a factor of two) of vertical movement, but a thousand or so large earthquakes during the last few million years could give us the impressive topographic relief that we see today. Owens Valley is the westernmost basin of the Basin and Range province of the western United States, a region in which grabens form as coastal California and Oregon pull away from the continental interior."

from: Geology Underfoot in Death Valley and Owens Valley, p. 195 Sharp & Glazner .