| Chico Formation | |
| Type: | Geological formation |
| Age: | Campanian Age, Cretaceous Period |
| Period: | Campanian |
| Prilithology: | sandstone |
| Namedfor: | Chico, California |
| Region: | California, Oregon |
| Country: | United States |
| Underlies: | Martinez Formation (regionally), Tejon Formation (regionally) |
| Overlies: | Vaqueros Formation |
The Chico Formation is a geologic formation of the Campanian Age during the Cretaceous Period, found in California and southern Oregon.
The MesozoicEra formation can regionally overlie the Vaqueros Formation, and can regionally underlie the Martinez Formation or Tejon Formation.
The Chico Formation is exposed in the Southern California Coast Ranges, western San Joaquin Valley, north of Mount Diablo, and in the Chico area of the northeastern Sacramento Valley.[1]
It is also found in the eastern Simi Hills in Bell Canyon and Dayton Canyon, located in Los Angeles and Ventura Counties, near the community of West Hills.[1]
Dinosaur remains are among the fossils that have been recovered from the formation, from the Late Cretaceous of the Mesozoic Era.[1] [2]
The lizard and bird species listed in the table below date from the Late Cretaceous Epoch.[1] [3] [4]
| Vertebrates of the Chico Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | Images |
| Clidastes[5] | ||||||
| Hesperornis[6] | ||||||
| Ichthyornis | ||||||
| indet. Pteranodontidae[7] | ||||||