The Arizona Geological Survey has released one of their more popular booklets as a free download: “A Guide to the Geology of Organ Pipe Cactus National Monument and the Pinacate Biosphere Reserve.”
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.
This 66-page booklet contains many great photos and illustrations. The first part gives a general description of the region. Parts 2 and 3 provide road logs and detailed descriptions and photos of specific geologic features of Organ Pipe and Pinacate respectively.
You can download the booklet here: http://repository.azgs.az.gov/sites/default/files/dlio/files/nid1685/dte-9-organ_pipe.pdf
Some other recent releases from AZGS:
A Guide to the Geology of the Santa Catalina Mountains
A guide to geologic feature of Petrified Forest National Park
Catalina State Park – Geology for the layman
AZGS Guides to Northern Arizona Geology
A guide to the geology of the Sedona & Oak Creek Canyon area of Arizona
wryheat 