Craters of the Moon National Monument and Preserve, Idaho
This 618-square-mile (1,600-square-kilometer) region bears an eerie resemblance to the meteor-battered lunar surface. Actually, though, its scarred landscape is the result of the stretching movement of Earth's crust over the past 30 million years. As the crust stretches, it releases pressure on to the hot rocks below, causing them to melt. The hot magma then flows along weaknesses in the surface and results in multiple periods of volcanic activity, the most recent one about 2,000 years ago.
During that eruption, lava burst from the Great Rift, a series of deep cracks that stretch for 52 miles (84 kilometers). The Craters of the Moon continues to be volatile, and scientists predict that it will experience future eruptions that will alter its surface [source: National Parks Service].