Crowder Formation

Crowder Formation
Stratigraphic range: Pliocene
Type	Geologic formation
Underlies	Harold Formation, Shoemaker Gravel
Overlies	Punchbowl Formation [1]
Location
Region	Mojave Desert, in San Gabriel Mountains and San Bernardino Mountains, Los Angeles County, San Bernardino County, California
Country	United States

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]

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.^{[ citation needed ]}

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

• California portal

• Neogene geologic formations in California
• List of fossiliferous stratigraphic units in California
• Paleontology in California

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.