 A monogenetic volcanic field, it consists of 13 basaltic to andesitic volcanic edifices that vary from 360,000 years old to 2,000 years old.They appear as a series of isolated lava flows emplaced as single units, except for the deposits at Bare Mountain, South Soda Peaks, and West Crater where deposits are more complex.West Crater is a small lava dome, made up of andesitic lava with two large lava flows.