South Fork of the Boise River, Smith Prairie Basalts

Geology Is Cool: Lava Dams


Idaho is a volcanologist’s paradise. The Columbia River basalts, the Snake River Plain, the Challis Group, and the comparatively minor events from basin and range faulting; you can’t walk very far in Idaho without stumbling over an igneous rock of some kind. Along the South Fork of the Boise River, lava flows have repeatedly dammed the…