Explain the formation of a waterfall

A waterfall is formed when a river flows over an area of land that has different levels of resistance to erosion. Typically, a river will flow over a layer of hard rock or other resistant material, which will slow down erosion. However, beneath this layer is a softer layer of rock that is more easily eroded. As the river flows over the hard layer, it cuts down into the soft layer, forming a deep channel.

Over time, the water erodes the soft rock layer more and more, causing the hard rock layer to hang over the channel. Eventually, the hard rock layer becomes too heavy and collapses, causing the waterfall to form. As the water falls over the edge, it creates a plunge pool at the base of the waterfall. The force of the falling water also causes the soft rock layer to erode further, which can cause the waterfall to retreat upstream over time.

The formation of a waterfall requires the right combination of geological factors, including different levels of rock resistance, a steep enough gradient to create a fast-flowing river, and enough water to maintain the flow. The process can take thousands or even millions of years, depending on the geology of the area and the strength of the water flow.