The two dark horizontal bands in the cliff on the left near Tower Junction in NE Yellowstone are lava flows that display prominent columnar jointing. The base of the cliff exposes volcanic materials of the Absaroka Formation. The light-colored rocks between the basaltic lava flows are stream-gravel sediments. The top of the hill consists of lake sediments.

Photo by Dan Dzurisin, 1983 (U.S. Geological Survey).

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Yellowstone