The Salton Buttes consist of five small rhyolitic lava domes extruded onto Quaternary sediments of the Colorado River delta within the Salton Sea geothermal field at the SE margin of the Salton Sea.  The summit of The age of the Salton Buttes has variously been considered to be late Pleistocene or early Holocene based on different dating techniques.  Recent dating of young zircons (which typically crystallize prior to eruption) at 10,300 +/- 1000 years Before Present (BP) is consistent with early Holocene hydration rind dates from Obsidian Butte.  Wave-cut benches originating from Lake Cahuilla, which existed from about 20,500 to 3000 BP prior to the 20th century formation of the Salton Sea due to an accidental spill-over of the Colorado River, are found on all of the domes.  Older, sediment-buried Pleistocene rhyolitic lava domes have been found in geothermal drill holes.  The Salton Sea geothermal field produces saline geothermal brines.