Mono Basin and Hot Creek Area

Panum Crater at the edge of Mono Lake is one of a series of volcanoes. Late in the Ice Age when the volcanoes began to form, the basin was covered by ancient Lake Russel that was 5 times the size of Mono Lake. Pumice, blasted out and carried by the winds, covers many square miles of ancient lake sediments and glacial debris to a depth of several feet.