page_title: Lava Beds National Monument
section_title: Lava tubes
hierarchical_section_title: Lava Beds National Monument / Geologic formations / Lava tubes
caption_attribution_description: Illuminated lava tube at en:Lava_Beds_National_Monument ,California
context_page_description: Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc counties. The monument lies on the northeastern flank of Medicine Lake Volcano and has the largest total area covered by a volcano in the Cascade Range.
  The region in and around Lava Beds National Monument lies at the junction of the Sierra-Klamath, Cascade, and Great Basin physiographic provinces. The monument was established as a national monument on November 21, 1925, and includes more than 46,000 acres.
  Lava Beds National Monument has numerous lava tubes, with 25 having marked entrances and developed trails for public access and exploration. The monument also offers trails through the high Great Basin xeric shrubland desert landscape and the volcanic field. In 1872 and 1873, the area was the site of the Modoc War, involving a band led by Kintpuash. The area of Captain Jack's Stronghold was named in his honor.
context_section_description: Lava flows dated to about 30,000–40,000 years ago formed most of the lava tubes in the monument. As the hot basaltic lava flowed downhill, the top cooled and crusted over, insulating the rest of the lava and forming lava tubes. Lavacicles on the ceiling of a lava tube were produced as the level of lava in the tube retreated and the viscous lava on the ceiling dripped as it cooled.
  Dripstone was created when lava splashed on the inside walls of the tubes. The leaching of minerals from pumice gravel, soils, and overlying rock provides for deposition of secondary speleothems in lava tubes.
  Lava Beds National Monument has the largest concentration of lava tubes in North America. One has electrical lighting, the others are illuminated by ceiling collapse portals or require flashlights, available on loan.
caption: An illuminated lava tube
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