Prospect Mountain Quartzite of Cambrian age is thrust over Paleozoic rocks as young as the Ely Limestone of Pennsylvanian age. The quartzite of the allochthonous plate was believed to be Ordovician-Silurian(?) and had been named Morehouse Quartzite. Overlying rocks are volcanics of Tertiary age. The San Francisco thrust is compared with similar thrusts in the Wah Wah Mountains and the Canyon Range and possibly formed in Late Jurassic(?) and Early Cretaceous.