How did mount diablo form?

Mount Diablo formed primarily as a result of tectonic activity associated with the San Andreas Fault system. It is a part of the Diablo Range, which emerged due to the uplift of the Earth's crust from the collision and interaction of tectonic plates. This geological activity, along with erosion and sedimentation over millions of years, shaped the mountain into its current form. The unique geology of the area also includes a mix of sedimentary and igneous rocks, contributing to Mount Diablo's distinctive features.