View Photo - Waterfall Informational Sign - Photo

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Waterfall Makers

Here the Yellowstone River plunges 308 feet over the Lower Falls. Hot springs have weakened the rock just downstream, where you might see several geysers 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.

[Lower image caption]
A waterfall is a clue that you are standing at a geologic crossroads.

[Caption for upper right image]
A small geyser vent beside the Yellowstone River.