Santiago Formation, California

Santiago Formation
Stratigraphic range: Late Eocene-Late Oligocene (Uintan-Duchesnean)
Type	Geological formation
Lithology
Primary	Siltstone, mudstone
Other	Sandstone
Location
Coordinates	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) Show map of the United States Santiago Formation, California (California) Show map of California

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 Walshina esmaraldensis and Diegoaelurus vanvalkenburghae, dating back to the Late Eocene to Late Oligocene periods (Uintan to Duchesnean in the NALMA classification).^[1]