Geology and paleontology of the Tesla Formation, Alameda and San Joaquin counties, central California

The Tesla area, which includes the type section of the Tesla Formation, encompasses about 30 km in the eastern part of the central Diablo Range. The geology of the Tesla area is typical of the Coast Ranges of California. Rock formations ranging in age from Jurassic to upper Miocene are involved in a complex of folds and faults. Three major faults divide the Tesla area into four structural blocks which differ in their style and complexity of structural deformation. All three faults were active during the Neogene, but have shown no Holocene activity. The oldest rocks, the Jurassic and Cretaceous Franciscan assemblage, consist primarily of graywackes, shales, and cherts and are faulted against mudstones and shales of the upper Jurassic Knoxville and Cretaceous Panoche Formations. Overlying and in fault contact with the Knoxville are marine shales, sandstones, and siltstones of the Panoche, which is conformably overlain by marine shales and sandstones of the upper Cretaceous Moreno Formation. Overlying the Moreno are sandstones of the middle Eocene, Paleocene?, and possibly upper Cretaceous Tesla Formation, the focus of this study. The Miocene Cierbo Sandstone unconformably overlies the Tesla and locally the formations are in fault contact. Non-marine sandstones and siltstones of the upper Miocene Neroly Formation overlie the Cierbo.