Lava Tubes

Lava tubes are long sinuous caves created during a basalt lava flow. The top of the lava cools first, but underneath, a "river" of lava keeps running, creating the tube. Sometimes multiple flows occur through the same lava tube, and the layers from the successive flows are easily visible on the walls of the lava tube. This is especially visible in Valentine Cave.

Other lava tube pictures from Lava Beds NM: Next: the rest of Lava Beds National Monument.