A waterfall is a place in a river where water suddenly drops down a big cliff or a rocky ledge. Here are some fun facts: The tallest waterfall in the world is Angel Falls in Venezuela, which is so high that some of the water turns into mist before it even hits the bottom! Waterfalls form because some rocks are "softer" than others. As the river flows, it wears away the soft rock faster than the hard rock, eventually creating a ledge for the water to spill over. This process is called erosion. There are different types of waterfalls: a "Block" waterfall is wide like a big wall (like Niagara Falls), while a "Horsetail" waterfall stays in contact with the rock as it slides down. Under the waterfall, the crashing water often digs out a deep "plunge pool." Some waterfalls are even "temporary," appearing only when the snow melts in the mountains. They aren't just pretty; they also help keep the water full of oxygen, which is great for the fish and plants living in the river!