Birch Mountains kimberlite field shales interbedded with kimberlite at some of the diatremes are consistent with a Late Cretaceous age (Late Albian to Maastrichtian). The volcanic rocks of the BM field consist primarily of crater-facies pyroclastic kimberlite and resedimented kimberlite. They include massive layers, as well as bedded and graded layers of coarse lapilli alternating with layers of finer tuff. Lapilli and olivine phenocrysts are set in a grey-green matrix of serpentine, carbonate minerals (calcite, dolomite and magnesite) and clay minerals. Phlogopite, oxide minerals (ilmenite, perovskite and spinel), apatite and pyrite are also present. Diamonds and microdiamonds have been recovered from samples taken from
Coso Rock Art District Coso Rock Art District Coso Rock Art District, containing the Big and Little Petroglyph Canyons, is a rock art site containing over 100,000 Paleo-Indian and/or Native American Petroglyphs. The Coso Range is between the Sierra Nevada and the Argus Range. Indian Wells Valley lies to the south of this location. This north-south trending range of about consists of rhyolitic domes and outcrops of volcanic rock. Also known as Little Petroglyph Canyon and Sand Tanks, Renegade Canyon is but one of several major canyons in the Coso Range, each hosting thousands of petroglyphs (other locations include Haiwee Springs, Dead End Canyon,