Craters of the Moon National Monument

Visited: April 2014

Nearby town: Arco, ID

This seemingly alien, lunar landscape in central Idaho is one of the best preserved flood basalt areas in the continental United States. A flood basalt is a result of a gigantic series of volcanic eruptions that covers a vast area of land with basalt lava. The eruptions that created Craters of the Moon National Monument occurred as recently as 2,000 years ago, but most of the lava flows in the park occurred around 15,000 years ago. There are more than 25 volcanic cones in the park. A 53 mile long weakness in the Earth's crust, known as the Great Rift Zone which is part of the larger Snake River Plain volcanic zone, makes for the best examples of volcanic geology in the US (outside of Hawaii).

The National Monument, created in 1924 and later expanded in 2000, is very unique and is well worth a detour. Most visitors stay a couple of hours to do the Loop Drive and some short hikes that highlight the main features of the park (basaltic lava, lava tubes, and caves).

Start your adventure at the Visitor Center along Highway 20/26/93. Then take the loop road. Our first stop was North Crater Flow Trail. This short walk is very enjoyable and a good preview of the park. If you only have time to do one trail/nature walk, make it this one.

These large cinder crags were very unique and impressive

The next stop are some excellent examples of spatter cones, a low, steep-sided hill consisting of welded lava fragments. 

spatter cones

Next up is Broken Top loop hike.

Another major highlight along the Loop Drive is the Indian Tunnel, a great lava tube to explore. A lava tube is created when flowing lava moves beneath the hardened surface of a lava flow, leaving a hollow, cylindrical cave. There are also some other caves you can go into, Boy Scout, Beauty, and Dewdrop Cave. We went briefly into Boy Scout cave.

Boy Scout cave was very icy inside

Craters of the Moon is an easy park to explore in half a day to a full day. There are not too many places in the US to see such examples of volcanic geology. More info here: https://www.nps.gov/crmo/index.htm