Montgomery Peak, California
(c) 2006 Andrew Alden, licensed to About.com (fair use policy)
The northern White Mountains are visible from the whole crest of the central Sierra Nevada, and Montgomery Peak is especially visible in late afternoon with its bare light-colored (leucocratic) granite, technically speaking an adamellite or quartz monzonite. Once contiguous with the Sierra Nevada, this crustal block separated from it during the middle Miocene, about 12 million years ago, then tilted strongly eastward, away from the viewer. The normal fault underlying the front of the range here changed to right-lateral about 3 million years ago as the Sierra Nevada microplate began its independent motion. Today the White Mountains mark the western edge of the true North American plate as well as the begining of the Basin and Range province.
