Question

Why is the erosive action of the rivers greater in the mountain than in plains?

Answer 1

Mountains are more like an inclined plane. When a water drop falls on the very top of the inclined plane it eventually starts to flow downwards. In the same manner, a river flows downwards from the mountain with a great force. On its way it also erodes the soil and transport it. But in case of plains the water does flow but not in a great force like in case of mountains. So, the erosive action of rivers is greater in the mountains than in the plains.