Craters of the Moon, national monument, Idaho. National Park. 'The strangest 75 miles on the North American Continent " claimed an early traveler. Great basaltic lava fields from when the earth opened in a great fissure erupting approx 15,000 years ago with eruptions up until last 2,000 years. There is no one volcano, rather a series of volcanic cones and lava flows forming part of the Great Rift zone. A surreal place to walk about with dark jagged rocks of peculiar shapes and sizes. Oct 2002.