Salton Sea Volcanoes

The Salton Buttes are a group of volcanoes in California, on the Salton Sea. They consist of a 7-kilometer (4.3 mi)-long row of five lava domes, named Mullet Island, North Red Hill, Obsidian Butte, Rock Hill and South Red Hill. They are closely associated with a fumarolic field and a geothermal field, and there is evidence of buried volcanoes underground. In pre-modern times Obsidian Butte was an important regional source of obsidian. The Salton Buttes lie within the Salton Trough, a tectonic depression formed by the San Andreas Fault and the San Jacinto Faults. The depression forms the northward extension of the Gulf of California, and is separated from it by the Colorado River Delta. A number of geothermal and volcanic features are located in the area, which is a region of active seafloor spreading. While the Salton Buttes were formerly considered to be of the late Pleistocene epoch (which ended with the end of the last glacial maximum), newer dating efforts have determined that all of them fo