As of 12/9/04, there are over 502 known caves and other lava tube features within the monument, with a combined length of over 28 miles. Lava Beds has the largest known concentration of lava tube caves in the lower 48 states. Caves in Lava Beds National Monument typically:
~ Were formed during the eruption of basaltic lavas in the late Pleistocene (over 10,000 years ago), a process which has not happened historically in the area, thus they are non-renewable geologic resources;
~ Are segments of several lava tube systems that once carried flowing lava as far as 10 mi (16.7 km) from its source;
~ Contain abundant well-preserved lava features such as levees and gutters, lava cascades, linings, balconies, natural bridges, lava lakes, rafted blocks, blisters, and lava stalactites and stalagmites;
~ Contain small secondary mineral deposits, including calcite, gypsum, and opal speleothems;
~ Contain areas of loose boulders, called breakdown, which formed from the collapse of the ceiling or walls;
~ Contain no streams; water, where present, is found as ice formations, isolated pools, condensation, and seepage;
~ Are home to a variety of wildlife, including many species of cave dwelling invertebrates, and rodents. Some of the caves contain significant seasonal or perennial ice formations. Many caves support bat populations, including one of the northernmost maternity colonies of Brazilian free-tailed bats (Tadarida brasiliensis)and the largest bat hibernaculum on the west coast. A relatively large population of Townsend's big-eared bats (Corynorhinus townsendii), a species of special concern, occupies monument caves throughout the year.
Many caves are culturally significant, both archaeologically and historically. Prehistoric rock art and artifacts in and near the entrances to caves are evidence of early human use of the caves. The caves of Lava Beds were well known and used by native Americans, as evidenced by pictographs and artifacts inside and close to cave entrances. Many cave-related archeological sites are documented in the monument. More recently, the Modocs used caves, collapses, and ledges to strategic advantage in the Modoc War of 1872-73, hiding from and firing on federal troops intent on removing them from the land. The major post-settlement discovery and exploration of the caves took place during the early part of this century, mainly by a local miller named J.D. Howard. His hobby from 1916 to 1936 was finding, exploring and naming caves. Other local settlers and explorers also assisted and lent their names to many caves, for example Heppe, Caldwell, Cox, Hopkins, Cooper brothers, and Kirk White. J.D. Howard, however, considered the Lava Beds his home. When news of his discoveries brought others to the caves, Howard sent a letter to the Forest Service (1923), which was one of many letters instrumental in the creation of the monument. In this particular letter he expressed his concerns about the caves and the need for their protection: "This place must be made a park and the keepers in charge. Indian Well is becoming a trash hole and this cave has the very best water in the Beds. I am sorry I made a road up to the place. Farther I am sorry I left the entrance to Catacombs open after I first entered. (I opened it and later enlarged it, then began to take visitors there, this has been a mistake.) I should have closed it again and left it unknown as the better stalactites are now gone except in the remote crawlers. I cannot put back the beauty of the Catacombs...." During the 1930's the CCC developed many of the caves to make them more accessible to the general public. Cave entrances were enlarged, stairways and ladders installed, and trails constructed. Many of these developments are maintained to this day. Also in the 1930's, a chemical and mining engineer named Walter Glaeser traversed the area identifying cave "prospects", but did not explore them thoroughly since much of the time he had no flashlight. He documented the location and character of 118 prospects, including eight he named and considered significant caves, none of which were ever developed for visitors. In summary, Lava Beds' caves are non-renewable resources, unique in their extent and degree of preservation, and are geologically, biologically, and culturally significant.