Waterfalls, plunge pools, and gorges are formed through the natural process of erosion. Waterfalls are typically found in the upper sections of rivers where fast moving water erodes away softer rock. As the waterfall erodes the rock over time, it carves out a deep plunge pool and gradually moves further upstream, leaving a gorge behind it. Victoria Falls on the Zambezi River in Zimbabwe is the largest waterfall in the world, formed as the river erodes cross faults of softer rock surrounded by harder basalt.