Type Geologic formation Named for Briones Hills | Country United States Underlies San Pablo Formation | |
Region Contra Costa County,
California | ||
The Briones Formation is an Late/Upper Miocene epoch geologic formation of the East Bay region in the San Francisco Bay Area, California.
It is found in western Contra Costa County.
It preserves fossils dating back to the Late/Upper Miocene epoch of the Neogene period.
References
Briones Formation Wikipedia(Text) CC BY-SA