On the flanks of Medicine Lake Volcano in remote Northern California is Lava Beds National Monument. In its higher altitudes, the park is covered in large ponderosa pines and firs. As it descends, the landscape gives way to sagebrush and bunch grasses. And beneath that is a sprawling network of some 800 lava tubes, caves carved out by flows of molten rock that date to between 65,000 and just 1,100 years ago. Some are just a few feet across, others some 60 feet around. The lava tube caves are home…
