This is the type area for the Irvingtonian Mammalian age, the best early Middle Pleistocene fauna in the West.

Among the mammals whose fossils have been recovered here are a number of genera still found in the Bay Area such as Citellus (ground squirrels), Thomomys (pocket gophers), Perognathus (deer mouse), Neotoma (packrat), Microtus (vole), Odocoileus (deer), and a coyote, Canis irvingtonensis.

Additionally there are a number of other species which are either extinct or whose descendants are found in other parts of the world. These include a ground sloth, Megalonyx, dire wolf, Canis dirus, sabre-tooth cat, Dinobastis, mammoth, Mammuthus columbi, horse, Equus, several peccaries of the family Tayassuidae, two species of camels, Camelops minidokae and Tanupolama sp., an antilocaprid with four horns, Tetrameryx irvingtonensis, and a musk-ox like animal, Euceratherium.

Integrity: Interstate 680 passes over the known fossil site; however, the fossils have been studied over a number of years and removed before construction. Road cuts have revealed additional sediments similar to the fossil-bearing sediments.

Use: Research only

Ref: Savage, D. B., 1952. Cenozoic Vertebrates of the San Francisco Bay Region. University of California Dept. Geol. Sci. Bull. 28, No. 8.

May 1975

Alameda
Inventory of California Natural Areas
Revision © 2005 Steven Louis Hartman