Road Trip Adventure- Volcanic Idaho

Continuing on our road trip, this week’s Nature Minute takes us to Idaho’s Craters of the Moon National Monument and Preserve. Located in south central Idaho, the area was once a hotbed of volcanic activity. Ancient lava flows created a unique landscape and habitat. Enjoy this week’s story from the road.

The lava flows that give Craters of the Moon its signature look and name sprang from the Great Rift between 15,000 and 2,000 years ago. The lava beds cover over 1000 square miles, flowing from 25 vents that spewed in at least 8 volcanic events during that time period. Craters of the Moon is the largest of several lava beds in the Great Rift.

Volcanic landscape of Craters of the Moon

Lava in the midground, sagebrush steppe in the
foreground and background

Geological features of the Monument are spatter cones, cinder cones, fissures, lava tubes, and kipukas. The cones and fissures are volcano types. Lava tubes and kipukas are formed by lava movement.

Spatter cones are formed when thick lava is ejected from a volcano. It remains molten when it hits the ground, but due to high viscosity, the blobs of lava do not flow away. Rather, new molten blobs are ejected and they stick together, forming a cone. Cinder cones form similarly, but the lava blobs cool and harden in mid-air, becoming lava bombs (actual geological term). The size and shape of the bombs is dependent on gas content.

Spatter cone (NPS photo)

Fissures are large volcanic cracks in the ground. A full-length fissure eruption is probably the rarest of all volcanic eruptions. Spatter and cinder cones can form in a fissure if it becomes clogged in any area. 

Lava tubes form when the outside of a lava flow cools, forming a hard rock shell. After the remaining molten lava drains, the hollow tube remains. I have been inside a lava tube, the Ape Cave at Mount Saint Helens in Washington.

Lava tube (Oregon State University photo)

Kipukas are islands of older lava flows surrounded by newer lava flows. Vegetation on kipukas is different from the surrounding lava flow areas. At Craters of the Moon, the kipukas are islands of sage steppe surrounded by black lava rock.

Kipuka (NPS photo)

Despite its barren appearance, Craters of the Moon supports a diverse ecological community. Plants include sagebrush, prickly pear, limber pine, and Indian paintbrush. Animals in the Monument include the pika, sage grouse, pygmy rabbits, northern harrier, and common nighthawk.

Limber pine

While visiting, I observed a northern harrier overhead. I took a nice stroll through the Devil’s Orchard, so named by a 19^th century preacher who failed to see beauty in Creation and declared the place to be a garden fit for the devil. I enjoyed seeing the lichen that are working around the clock to turn rock into soil so larger plants can colonize. The twisted branches of the limber pine, knotted by mistletoe, set against a stark black backdrop made for an eerie sight. I enjoyed my brief visit and would like to return for a more in-depth look around. I chose not to linger because Craters of the Moon was the undercard for the main even, Yellowstone.

Limber pine with "witch's brooms"

Polished lava rock with swirls

Hardened slow-moving lava flow

Information this week comes from the National Park Service about kipukas, including the picture above. Great Rift information comes from a paper by the folks at Idaho State University. Photo credits go to National Park Service (spatter cone) and Oregon State University (lava tube). All others are my own.