A stream or river that plunges down a naturally sheer rock face.

A waterfall spilling over a ledge of hard rock, British Columbia.

Some waterfalls have been produced by hard bands of horizontal rock, others by the scouring action of glaciers, and yet others by rapid uplift of the land.

The highest waterfall is the Angel Falls in Venezuela. It is 980m/3300ft high.

In a mountain environment, most waterfalls spill from hanging valleys into the bottom of deeper U-shaped glacial valleys. The ones shown here are in Yosemite National Park, California.

Nevada Falls.

Yosemite Falls.