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 | |
| 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 |
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 edit
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 edit
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 edit
References edit
- ^ 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.
- ^ a b c 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.
- ^ a b c San Bernardino County Museum: "Miocene Faunas in the Lower Crowder Formation", by R.E. Reynolds, 1984.
- ^ a b 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.
- ^ 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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