Nonconformity separating Mesozoic granitic rocks (foreground) from Pliocene volcanic rocks and mudflows of the Mehrten Formation (background). Photograph taken along Highway 108 in the Stanislaus National Forest, Sierra Nevada, California.

This photograph was published in June 1999 on the back cover of the book "Geologic Field Trips in Northern California," in conjunction with the Centennial Meeting of the Cordilleran Section of the Geological Society of America. This guidebook is available through the California Division of Mines and Geology as Special Publication 119.