A waterfall is a place where water flows over a vertical drop or a series of steep drops in the course of a stream or river. They are typically formed when a river flows over a resistant rock bed that erodes slowly, while the downstream rock is softer and erodes more quickly.

Here are some key characteristics of waterfalls:

• Formation: Waterfalls are often created when a layer of hard rock lies over a layer of softer rock. The softer rock erodes more quickly due to hydraulic action and abrasion, undermining the harder rock, which eventually collapses and creates the waterfall.
• Erosion: The force of the water falling over the edge erodes the plunge pool at the base of the waterfall. This erosion can cause the waterfall to retreat upstream over time.
• Types: Waterfalls come in various forms, including plunge, tiered, horsetail, and cascade waterfalls, each distinguished by the way the water descends.
• Ecological Importance: Waterfalls can create unique habitats for plants and animals.

For more information, you can check out these resources:

• World Waterfall Database - Waterfall Types
• Britannica - Waterfall