Archive - Owens Valley
January 29, 2022
Every weekend we present a notable item from our archives.
This EPOD was originally published July 12, 2007.
Provided and copyright by: Jim Trexler, University of Nevada, Reno
Summary authors & editors: Jim Trexler
This photo shows Owens Valley, California, looking north toward Bishop, about 60 miles (100 km) away. I'm standing in the western foothills of the Inyo Mountains, which is east of Independence, California, and I'm observing several important tectonic features spanning the last 250 million years. In the middle ground are ridges consisting of Permian and Triassic sedimentary rocks, dipping steeply to the west (left). The vertical-appearing, hard gray outcrops in the central ridge are the Triassic Union Wash Formation, which is well known for abundant and well-preserved ammonoid fossils. The boundary between the gray and white layers and the brown slopes to the right marks the unconformity associated with the Sonoma orogeny. This was an important tectonic collision event in the early Triassic. Note that the beds here stand on edge because of folding during the Jurassic and Cretaceous Sevier orogeny -- an ocean-continent collision. In the background at left is the Sierra Nevada range, composed of Jurassic and Cretaceous granite. This area is being uplifted today due to extension and transform faulting. The relief from the valley floor to Mt. Whitney (out of view to the left) is over 10,000 feet (3,048 m). Photo taken on May 25, 2007.