Moraga Formation

The Moraga Formation or Moraga Volcanics is a Pliocene epoch volcanic geologic formation in the Berkeley Hills of the East Bay region of the San Francisco Bay Area, California.
The basaltic lava flow formation is found within Alameda County and Contra Costa County. It can be seen in the Robert Sibley Volcanic Regional Preserve and Caldecott Tunnel area of the Berkeley Hills. It is named for an exposed occurrence in the Moraga Valley.
It overlies the Orinda Formation, and underlies the Siesta Formation of Great Valley Group.
It preserves freshwater fossils dating back to the Pliocene epoch of the Neogene period.