Craters of the Moon National Monument-Arco, ID

Craters of the Moon National Monument and Preserve protects the deepest-known split in the Earth—Idaho’s Great Rift—where the continental crust is thinning and breaking apart and allowing lava to spill onto the surface. The National Park Service (NPS) site contains over 1,000 square miles of flood basalts and other volcanic features such as lava tubes, spatter cones, and tree molds—the impressions left over in rock after hot lava incinerates forests.