Waterfall Makers

Here the Yellowstone River plunges 308 feet over the Lower Falls. Hot springs have weakened the rock jut downstream, where several geysers may be seen spouting into the river. As falling water pounds the thermally softened rock, it continues to undercut the falls and deepen the gorge. In this geologically active landscape, the park’s riverbeds drop abruptly in more than a hundred locations. A half-mile upstream, the Upper Falls formed at a junction of a lava flow and glacial lake sediments, one dense and hard, the other brittle and easily eroded.

Wyoming · United States