Skip to main content
U.S. flag

An official website of the United States government

Cross section thru a six-sided column of basalt, Sheepeaters Cliff

Detailed Description

Columns of the Sheepeaters Cliff represent cooling fractures that commonly develop in thick lava flows. As hot lava cools, it contracts, often forming a regular set of joints perpendicular to the cooling surfaces (top, bottom, and sides). The joints may produce regular polygonal columns, plates, or irregularly shaped fragments. Such cooling features also develop in welded tuffs.


Public Domain.