(This is part one of my vacation review. My wife and I stayed at a resort near Klamath Falls. From there we traveled to some amazing places in southern Oregon and northern California.)
About one million years ago during the Pleistocene Epoch the massive Medicine Lake Volcano began forming. Characterized by lava flows, rather than more explosive eruptions like at Mount St. Helens, this shield volcano has erupted on and off again throughout its history, with the most recent occurring about 1,000 years ago. Medicine Lake is the largest volcano by volume in the Cascade Range, having formed slowly with layer upon layer of lava flows.
Lava Beds National Monument in northern California is a fascinating example of some of these eruptions, and is located on the northeast flank of Medicine Lake Volcano. Surface lava flows and cinder cones dot the landscape, but the most impressive features are the monument’s extensive network of lava tube caves. Over 700 caves have been discovered here, making it the highest concentration of caves in the contiguous United States. Eruptions at Mammoth Crater 30,000 years ago sent expansive flows of lava as far as ten miles downhill. Lava tubes were formed when the edges of highly fluid, 1,800-degree Fahrenheit flows of lava started to cool. Eventually a roof forms that insulates the liquid lava inside. When the eruption stops and the hot lava drains out, a lava tube (the outer shell) is left. When portions of a tube’s ceilings collapse, they give access to the caves below.