Moraga Formation

Moraga Formation
(Moraga Volcanics)
Stratigraphic range: Pliocene epoch
Type Geologic formation
Underlies Siesta Formation
of Great Valley Group
Overlies Orinda Formation
Thickness 1,200 feet (370 m)
Lithology
Primary Basaltic lava, with
andesite, basalt, rhyolite tuff
Other Clay, conglomerate, limestone
Location
Region Berkeley Hills,
Alameda County and
Contra Costa County,
California
Country United States
Type section
Named for Moraga Valley

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. [1]

The basaltic lava flow formation is found within Alameda County and Contra Costa County. [2][1] It can be seen in the Robert Sibley Volcanic Regional Preserve and Caldecott Tunnel area of the Berkeley Hills. [3] 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. [4]

Fossils

It preserves freshwater fossils dating back to the Pliocene epoch of the Neogene period. [5]

See also

References

  1. 1 2 USGS.gov: "Upper Cretaceous and Lower Tertiary Rocks Berkeley and San Leandro Hills, California", by J. E. Case, GEOLOGICAL SURVEY BULLETIN 1251-J, 1968.
  2. ↑ Oakland Geology Blog: "Grizzly Peak and Moraga basalt"
  3. ↑ Geology.about.com: "California Transect - Stop 30, Orinda Formation and Moraga Volcanics"
  4. ↑ Lawrence Berkeley Lab.gov: "Berkeley Lab Geologist Studies the Ground Beneath His Feet"
  5. ↑ Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.



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