Question
Discuss the processes of erosion by a river and write about two landforms produced by river erosion with diagrams
Answer
The process of erosion by a river involves the wearing away of the earth’s surface by the force of moving water. The river’s water and sediment act as tools of erosion, which gradually cut through and remove soil, rock, and other materials from the riverbed and banks. The process of erosion by a river is classified into three types, including hydraulic action, abrasion, and attrition.
Two common landforms produced by river erosion are U-shaped valleys and hanging valleys.
- U-shaped valleys are formed in the upper course of a river where the erosive power of the river is at its highest. The river erodes downwards and sideways, cutting into the surrounding rock and widening the valley. The shape of the valley is gradually changed from a V-shape to a U-shape. This process is called glacial erosion and is often caused by the movement of glaciers. The result is a valley with steep sides and a flat bottom.
- Hanging valleys are formed when a smaller tributary valley meets the main valley. The tributary valley is typically eroded at a faster rate than the main valley due to differences in volume and velocity of water flow. As a result, the tributary valley is left “hanging” above the main valley. This creates a waterfall or steep drop-off from the higher valley to the lower valley.
