Crowder Formation

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Crowder Formation
Stratigraphic range: Pliocene epoch of Neogene Period
Type Geologic formation
Underlies Harold Formation, Shoemaker Gravel
Overlies San Francisquito Formation (western area), San Gabriel Basement Complex
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.[1]

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.[1][2][3]

Geology[edit]

The Crowder Formation was formed during the Pliocene epoch of the Neogene period.[1][2] The formation was deposited by drainages carrying distinctive volcanic and metamorphic clasts from the Victorville area southward.[3]

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[edit]

The formation preserves fossils of prehistoric insects, reptiles, rodents, birds, and larger mammals. The species date back to the Miocene and Pliocene epochs of the Neogene period.[4] 29 taxa were collected by the San Bernardino County Museum from the Cajon Pass area of the Crowder Formation.[2]

See also[edit]

References[edit]

  1. ^ a b c Seismo.berkeley.edu: Field Guide to the Punchbowl Fault Zone, at Devil's Punchbowl Los Angeles County Park; San Andreas Fault Resources; University of California, Berkeley; by Frederick M. Chester; January 1999.
  2. ^ a b c San Bernardino County Museum: "Miocene Faunas in the Lower Crowder Formation", by R.E. Reynolds, 1984.
  3. ^ 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.
  4. ^ Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014. 
  • "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.
Neogene Period
Miocene Pliocene
Aquitanian | Burdigalian
Langhian | Serravallian
Tortonian | Messinian
Zanclean | Piacenzian