Type Geologic formation Overlies Bald Peak Basalt | Underlies Leona Rhyolite | |
Region Berkeley Hills andSan Leandro Hills,Alameda County andContra Costa County,California | ||
The Mulholland Formation is a Pliocene epoch geologic formation in the Berkeley Hills and San Leandro Hills of the East Bay region of the San Francisco Bay Area, California. It is found within Alameda County and Contra Costa County.
Contents
Geology
It overlies the Bald Peak Basalt formation, and underlies the Pleistocene epoch Leona Rhyolite formation. It is composed of siltstone, sandstone, and conglomerates. It has fluviatile and lacustrine deposits.
Descending under the Bald Peak Basalt formation are the Pliocene epoch units of the Siesta Formation, Moraga Formation, and Orinda Formation. Below the Orinda are the local Miocene epoch units of the Monterey Formation Group: Tice Shale, Oursan Sandstone, Claremont Shale, and Sobrante Sandstone.
Fossils
The Mulholland Formation preserves fossils dating back to the Neogene period.