How is a waterfall formed?
Water falls over Hard rock. When it reaches the soft rock, the water starts to wear away the soft rock, this is called erosion. Over hundreds or even thousands of years, the soft rock is slowly eaten away or eroded and the river begins to cut down further into the soft rock. This makes a cliff over which the water can topple. Over time, the cliff becomes steeper as more soft rock is eroded, and deeper as bigger boulders come over the waterfall, and the ground gets beaten with more and more rocks until it creates a plunge pool. Some of the water goes under the waterfall and under cuts the soft rock. More of the hard rock begins to fall away and the waterfall slowly moves upstream.
