Ocotillo Formation
The Ocotillo Formation is a Pliocene fluvial-alluvial fan geologic formation in the Colorado Desert of Southern California. It occurs in western Imperial County and eastern San Diego County. Geology. The formation overlies the Brawley Formation and the Palm Spring Formation. In the Mecca Hills, it is younger than 765,000 years. Fossils. It preserves fossils and petrified wood, from the Pliocene Epoch of the Neogene Period, within Anza-Borrego Desert State Park.