Mount Hannah is a 3,692-foot peak in Lake County, California, within the Cobb Mountain area of the Mayacamas Mountains, where volcanic peaks and small valleys shape the rugged uplands. Though overshadowed nearby by Cobb Mountain, it stands out for its distinct rise above surrounding terrain, with 1,338 feet of prominence and 7.94 kilometres of isolation. Geologically, it formed rapidly in the early Pleistocene during a polarity transition through a series of closely spaced eruptions. Three dacite units date to between 0.90 and 0.92 million years ago, and evidence of a deep magma chamber beneath it links Mount Hannah to the region’s long volcanic history.