Waterfall

Notes (a) River flows over an area where there are bands of softer and harder rocks, (b) softer rock is more quickly eroded, (c) the river undercuts the harder rock leaving an overhang, (d) the river forms a plunge pool below the waterfall, (e) overhanging rock is unsupported and falls into the plunge pool, (f) the waterfall is moved upstream, (g) as this process continues a gorge is cut back into the hillside.