Amboy Crater and Lava Field is an extinct North American cinder cone type of volcano that rises above a 70-square-kilometer (27 sq mi) lava field in southern California's Mojave Desert. Estimated at 6,000 years old, with last eruption as recently as 500 years ago. Crater about 250 ft (76m) high. Designated "Amboy Crater National Natural Landmark" in May, 1973.