Eocene anauxite clays and sands containing andalusite occur at Tesla, Brentwood, and the Potrero Hills in the Coast Range as well as under the Great Valley at Rio Vista and McDonald Island. The fossil evidence suggests that these sediments were deposited in Meganos D, Capay, and Domengine stages of the Eocene. The type Capay in the Coast Range contains no anauxite or andalusite. Therefore, it is proposed herein that the anauxite sands and clays of the Coast Range were deposited by Eocene streams flowing across the area which is now the Great Valley and deriving sediment from the same source in the Sierra Nevada that furnished the anauxite sands of the Ione formation of Capay stage. The anauxite sediments of the Coast Range and Great Valley areas were mixed with sediments derived from a Coast Range source.
- Received 18 September 1940.
- © 1941 Geological Society of America