Mulholland Formation
Stratigraphic range: Pliocene epoch
Neogene Period
TypeGeologic formation
UnderliesLeona Rhyolite
OverliesBald Peak Basalt
Lithology
Primarysiltstone,
sandstone,
conglomerates
Location
RegionBerkeley Hills and
San Leandro Hills,
Alameda County and
Contra Costa County,
California
CountryUnited States
Type section
Named forWilliam Mulholland

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.[1] It is found within Alameda County and Contra Costa County.[1]

Geology

It overlies the Bald Peak Basalt formation, and underlies the Pleistocene epoch Leona Rhyolite formation.[1] It is composed of siltstone, sandstone, and conglomerates. It has fluviatile and lacustrine deposits.[1]

Descending under the Bald Peak Basalt formation are the Pliocene epoch units of the Siesta Formation, Moraga Formation, and Orinda Formation.[1] Below the Orinda are the local Miocene epoch units of the Monterey Formation Group: Tice Shale, Oursan Sandstone, Claremont Shale, and Sobrante Sandstone.[1]

Fossils

The Mulholland Formation preserves fossils dating back to the Neogene period.[2]

Other local formations

  • Units of other local formations in the Berkeley and San Leandro Hills, in descending geologic column order from higher/younger to lower/older, include:[1]
  • Redwood Canyon Formation — sandstone, shale, and conglomerate.
  • Shephard Creek Formation — shale and sandstone.
  • Oakland Conglomerate — conglomerate, exposed on Skyline Boulevard.
  • Joaquin Miller Formation — sandstone, shale, and conglomerate.
  • Knoxville Conglomerate

See also

References

  1. 1 2 3 4 5 6 7 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. ↑ Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.


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