Almost looks like two summits but the tuff is at the saddle and the summit is made up of volcanic rock from ancient lava flows. Geologists theorize that the tuff on Brown’s Mountain was deposited during volcanic activity occurring in the Superstition area around 15 to 25 million years ago. The black basalt rock visible at the top of Brown’s Mountain is quickly-cooled lava that was deposited on the mountain during the same epoch.