Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc Counties. The Monument lies on the northeastern flank of the Medicine Lake Volcano, with the largest total area covered by a volcano in the Cascade Range. Lava Beds National Monument is a land of turmoil, both geological and historical. Over the last half-million years, volcanic eruptions on the Medicine Lake shield volcano have created a rugged landscape dotted with diverse volcanic features.
The region in and around Lava Beds Monument is unique because it lies on the junction of the Sierra-Klamath, Cascade, and the Great Basin physiographic provinces. The Monument was established as a United States National Monument on November 21, 1925, including over 46,000 acres. Humans have inhabited the Lava Beds area for at least 10,000 years. Cultural sites ranging from 6,000 year old pictographs and petroglyphs, to Modoc War sites from 1872-73, to artifacts left by early cave explorers in the 1920s can be found throughout the park.
Lava Beds National Monument has the largest concentration of lava tube caves in North America. One has electrical lighting, the others are illuminated by ceiling collapse portals or require flashlights, available to loan.
The high elevation, semi-arid desert environment of Lava Beds Monument receives an average of 14.8 inches of annual precipitation, including 44 inches of snowfall. The climate is characterized by warm, dry summers and cold, moderately snowy winters. A series of small earthquakes in late 1988 has been attributed to subsidence in the caldera. N-NE trending ground cracks, as well as N-NE trending vent series show relationships between tectonism and volcanism. One very prevalent ground crack exists along the northeastern boundary of the monument, The Big Crack. The only expansion in the modern era occurred in 2011 when the monument expanded by roughly 132 acres. An administrative transfer brought two parcels of land which were previously managed by the Bureau of Reclamation and the Bureau of Land Management into National Park Service management. These two parcels adjoin the Petroglyph Point Unit of the monument.
During the Modoc War of 1872-1873, the Modoc Indians used these tortuous lava flows of their homeland to defend their territory. Under the leadership of Native American Captain Jack, the Modoc's took refuge in Captain Jack's Stronghold, a natural lava fortress. From this base a group of 53 fighting men and their families held off US Army forces, that numbered up to ten times the Modocs' population, for five months. General E.R.S. Canby was killed here in April 1873 by Captain Jack at a meeting attempting to negotiate peace terms.