A waterfall can occur due to, for example, an earthquake or a plate shift. This causes the water to fall off the cliff that is currently being created. A waterfall can also occur gradually. If there are different types of soil in a river, such as hard and soft types of stone, part can be worn out. While the other part of the stone types remains at the same level. This creates height differences. Because the soft bottom wears out, the slope becomes increasingly steeper and steeper. This causes the water to f