San Francisquito Formation

The San Francisquito Formation is a geologic formation in northern Los Angeles County, California.[1][2]

San Francisquito Formation
Stratigraphic range: Maastrichtian-Danian
~70–62 Ma
TypeGeologic formation
UnderliesCastaic & Punchbowl Formations
OverliesSan Gabriel Basement Complex
Thickness4 km (13,000 ft)
Lithology
PrimarySandy shale
Location
Coordinates34.6°N 118.6°W / 34.6; -118.6
Approximate paleocoordinates39.5°N 96.5°W / 39.5; -96.5
RegionLos Angeles County, California
Country United States
ExtentSan Gabriel Mountains & Sierra Pelona Mountains
San Francisquito Formation (the United States)
San Francisquito Formation (California)

Areas where it is exposed include: San Francisquito Canyon of the Sierra Pelona Mountains, and the northwestern side of the Devil's Punchbowl gorge in the San Gabriel Mountains.[1][2]

Geology

The San Francisquito Formation is from marine deposits of the Late Cretaceous period of the Mesozoic Era, and the Early Paleocene epoch in the Paleogene period of the Cenozoic Era.[1][2] It is overlain by the Punchbowl Formation (east) and Castaic Formation (west), both of the Miocene and Pliocene epochs.[1] It overlies the crystalline San Gabriel Basement Complex.[1]

It is found between the San Andreas Fault on its north, and the Devil's Punchbowl Fault on its south.[1][2] The Pliocene epoch Crowder Formation is to the northeast.[1]

Fossil content

It preserves fossils dating back to the Paleogene period.[3]

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See also

References
  1. 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. AAPG Datapages/Archives: "Stratigraphy and Sedimentology of the Type San Francisquito Formation, Southern California"; Department of Earth Sciences, University of California, Riverside; 1982.
  3. Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.


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