The Mono-Inyo chain of craters lies in east-central California, roughly parallel to the eastern escarpment of the Sierra Nevada mountain range. Volcanism and seismic activity in eastern California are a result of two major geologic processes: northwest movement of the Pacific Plate with respect to the North American Plate along the San Andreas Fault system near the coast, and east-west extension of the crust that formed the Basin and Range Province.: In the Long Valley region, where the craters are located, basin and range extension encroaches onto the thick and stable crust of the Sierra Nevada.