The Summerville formation is below the Morrison formation and above the Curtis formation. It was deposited during the late Jurassic period, during a time of marginal marine and tidal activity. The stratigraphical region is a transgressive-regressive sequence. The paleolatitude (historic location) ranges from 5 to 25 degrees north and the paleoclimate was intensely hot and arid. It has thin red beds of rippled sandstones formed by tidal plains in the area. The formation is part of the SanRafeal group of rocks.