(looking ~west) (photo stitch by Mary Ellen St. John)

This photo shows part of the extensive Sierra Nevada Mountains of eastern California, USA. The mountains are dominated by a large igneous plutonic complex called the Sierra Nevada Batholith. The batholith is a suite of intrusive igneous rocks representing old, cooled magma chambers that were originally beneath an ancient chain of subduction zone volcanoes. The rocks are mostly Cretaceous-aged granite and granite-like lithologies such as granodiorite. Some sedimentary and metamorphic rocks are present in places - they represent roof rocks & altered roof rocks above the original magma chambers.

The Sierra Nevada Mountains were apparently uplifted starting in the late Mesozoic. Their high relief was acquired during Basin and Range extensional tectonics in the Tertiary, and especially during the Miocene, when normal faulting resulted in the downdropping of the graben block known as Owens Valley (= bottom foreground).

The prominent peak at right is Mt. Tom.