Santiago Formation, California

Santiago Formation Stratigraphic range: Late Eocene-Late Oligocene (Uintan-Duchesnean)
Type	Formation
Lithology
Primary	Siltstone, mudstone
Other	Sandstone
Location
Coordinates	33°06′N 117°18′W / 33.1°N 117.3°W / 33.1; -117.3Coordinates: 33°06′N 117°18′W / 33.1°N 117.3°W / 33.1; -117.3
Approximate paleocoordinates	33°18′N 104°06′W / 33.3°N 104.1°W / 33.3; -104.1
Region	Orange & NW San Diego County, California
Country	United States
Santiago Formation, California (the United States) Santiago Formation, California (California) Show map of the United StatesShow map of CaliforniaShow all

The Santiago Formation is a geologic formation in Orange and northwestern San Diego County, California. The siltstones, mudstones and sandstones of the formation preserve fossils of , dating back to the Late Eocene to Late Oligocene periods (Uintan to Duchesnean in the NALMA classification).^[1]

Depositional environment[]

The only paleoenvironmental interpretation based exclusively on specimens from the Santiago Formation is a study of land snails from SDSNH locality 3276 (Member C, ), which found the distribution of shell sizes and shapes to be consistent with interpretations of subtropical to tropical conditions and paleotemperatures in excess of 25 °C (77 °F).^[2]

See also[]

• List of fossiliferous stratigraphic units in California
• Paleontology in California

References[]

Bibliography[]

• López Torres, S.; M.T. Silcox, and P.A. Holroyd. 2018. New omomyoids (Euprimates, Mammalia) from the late Uintan of southern California, USA, and the question of the extinction of the Paromomyidae (Plesiadapiformes, Primates). Palaeontologia Electronica 21. 1–28. Accessed 2020-03-15.

Further reading[]

• Prothero, D.R. 2001. Magnetic stratigraphy of the middle-upper Eocene Santiago Formation, Orange and San Diego Counties, California. Guidebook, Pacific Section, Society of Economic Paleontologists and Mineralogists, 91:107-118