Online release of our guide to geology of Organ Pipe Cactus National Monument and Pinacate Biological Preserve

Organ Pipe Cactus National Monument in SW Arizona and the Pinacate Biosphere Reserve in NW Sonora protect two magnificent yet geologically distinct parts of the Sonoran Desert. Rocks of the Organ Pipe-Pinacate region have been faulted and eroded into mountains and basins typical of the Basin and Range Province of SW North America. The Biosphere Reserve contains young volcanoes, basalt lava flows, and giant maar craters on the Pinacate Volcanic field. This booklet is your field guide to the geology of these splendid desert landscapes.

http://repository.azgs.az.gov/uri_gin/azgs/dlio/1685