Carrizo Plain is a vast enclosed grassland in southeastern San Luis Obispo County and the largest single remnant of native grassland in California. Bordered by the Temblor and Caliente ranges and marked along its eastern edge by the San Andreas Fault, it is especially important for the visibility of active geologic features such as Wallace Creek, displaced by repeated fault movement. The plain also contains Soda Lake, Caliente Mountain, and Painted Rock, where Chumash and Yokuts pictographs preserve deep cultural history. Ecologically, it supports California’s greatest concentration of listed endangered species, and protection begun in 1988 expanded with national monument status in 2001.