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.USGS.gov: "Upper Cretaceous and Lower Tertiary Rocks Berkeley and San Leandro Hills, California"
by J. E. Case, GEOLOGICAL SURVEY BULLETIN 1251-J, 1968. The basaltic lava flow formation is found within Alameda County and

Contra Costa County ) of the San Francisco Bay , subdivision_type = Country , subdivision_name = United States , subdivision_type1 = State , subdivision_name1 = California , subdivision_type2 ...

. 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 The Siesta Formation is a geologic formation in California. It preserves fossils dating back to the Neogene period. See also * List of fossiliferous stratigraphic units in California This article contains a list of fossil-bearing stratigraphic ...

of Great Valley Group. ;Fossils It preserves freshwater

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

dating back to the Pliocene epoch of the

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

period.

References

External links

East Bay Regional Parks.org: official Robert Sibley Volcanic Regional Preserve websiteEBparks.org: Volcanism at Sibley Volcanic Preserve
Berkeley Hills Pliocene California Geologic formations of California Geology of Alameda County, California Geology of Contra Costa County, California Natural history of the California Coast Ranges Natural history of the San Francisco Bay Area Volcanism of California Pliocene Series of North America Pliocene volcanism {{Neogene-stub