Forbes Shale

The Forbes Shale is a geologic formation in the Sacramento Valley of northern California, United States. It is found in the Sutter Buttes area of Sutter County, California. It preserves fossils dating back to the Coniacian stage of the Late Cretaceous period.

Forbes Shale
Stratigraphic range: Coniacian ~
Type	Formation
Unit of	Asuncion Group
Underlies	Kione Sands
Overlies	Funks Shale
Thickness	1,300 ft (400 m)
Lithology
Primary	Shale
Location
Coordinates	38.6°N 122.0°W / 38.6; -122.0
Approximate paleocoordinates	42.8°N 86.5°W / 42.8; -86.5
Region	California
Country	United States
Extent	Sacramento Valley
Forbes Shale (the United States) Forbes Shale (California)

Fossil content

The following fossils were reported from the formation:

Bivalves

• Cladoceramus undulatoplicatus
• Glycymerita veatchii
• Inoceramus subundatus
• I. Inoceramus vancouverensis
• I. aff. chicoensis
• I. aff. klamathensis
• I. aff. whitneyi
• Parallelodon|Parallelodon (Nanonavis) brewerlanus
• Pseudomelania colusaensis

Gastropods

• Bernaya (Protocypraea) kayei
• Biplica obliqua
• Dentalium (Entalis) whiteavesi
• Pseudomelania colusaensis
• Tessarolax distorta
• Volutoderma californica

Ammonites

• Baculites chicoensis
• B. inornatus
• Desmophyllites diphylloides
• Eupachydiscus arbucklensis
• E. willgreeni
• Eutrephoceras campbelli
• Lytoceras (Gaudryceras) alamedense
• Nowakites dobbinsi
• N. rumseyensis
• Oxybeloceras petrolense
• Parapachydiscus cortinaensis
• Puzosia (Holcodiscoides) gorrilli
• Puzosia (Parapuzosia) arenaica
• Baculites sp.
• Canadoceras sp.
• Hauericeras sp.

See also

• Cretaceous California
• List of fossiliferous stratigraphic units in California

References

Bibliography

• Anderson, F. M (1958), "Upper Cretaceous of the Pacific Coast", Geological Society of America Memoir, Geological Society of America Memoirs, 71: 1–378, doi:10.1130/MEM71-p1

Further reading

• Google Books: The Sutter Buttes of California: A Study of Plio-Pleistocene Volcanism; Howel Williams, Garniss H. Curtis.