Region, northern California, U.S. It features recent lava flows and related volcanic formations, including deep chasms, chimneys, and cinder cones that rise to 300 ft (90 m) in height.
The main battle sites of the Modoc Indian war (187273) are located within the monument, which occupies an area of 72 sq mi (186 sq km). It was dedicated as a national monument in 1925.