Crowder Formation

The Crowder Formation is a geologic formation in the Central and Western Mojave Desert, in northern Los Angeles County and eastern San Bernardino County, in Southern California.[2]

Crowder Formation
Stratigraphic range: Pliocene
TypeGeologic formation
UnderliesHarold Formation, Shoemaker Gravel
OverliesPunchbowl Formation[1]
Location
RegionMojave Desert,
in San Gabriel Mountains and San Bernardino Mountains,
Los Angeles County, San Bernardino County,
California
CountryUnited States

Areas where it is exposed include at the bases of the northern San Gabriel Mountains and northwestern San Bernardino Mountains, and in the Cajon Pass between them.[2][3][4]

Geology

The Crowder Formation was formed during the Pliocene epoch of the Neogene period.[2][3] The formation was deposited by drainages carrying distinctive volcanic and metamorphic clasts from the Victorville area southward.[4]

It overlies the crystalline San Gabriel Basement Complex in its eastern section, and the San Francisquito Formation in its western section in the Antelope Valley/San Gabriels.

Fossils

The formation preserves fossils of insects, reptiles, rodents, birds, and larger mammals. The species date back to the Miocene and Pliocene epochs of the Neogene period.[5] 29 taxa were collected by the San Bernardino County Museum from the Cajon Pass area of the Crowder Formation.[3]

See also

References
  1. Thomas W. Dibblee (1967). "Areal geology of the western Mojave Desert, California" (PDF). Geological Survey Professional Paper. 522: 49. doi:10.3133/PP522. ISSN 0096-0446. Wikidata Q57842316.
  2. Seismo.berkeley.edu: Field Guide to the Punchbowl Fault Zone, at Devil's Punchbowl Los Angeles County Park Archived 2016-03-05 at the Wayback Machine; San Andreas Fault Resources; University of California, Berkeley; by Frederick M. Chester; January 1999.
  3. San Bernardino County Museum: "Miocene Faunas in the Lower Crowder Formation", by R.E. Reynolds, 1984.
  4. Caltech Thesis: "Neotectonics of the north frontal fault system of the San Bernardino Mountains, southern California : Cajon Pass to Lucerne Valley", Meisling, Kristian Erik (1984), Dissertation (Ph.D.), California Institute of Technology.
  5. Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.
  • "The Physical and Magnetic Stratigraphy of the Miocene Crowder Formation, Cajon Pass, Southern California"; by Douglas Scott Winston, University of Southern California; Los Angeles, 1985.


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