As a river flows, the force of its moving water washes away loose soil and pieces of rock. In this way the river cuts its own channel in the ground. The process of wearing away rocks is called erosion.
Erosion involves the wearing away of rock and soil found along the river bed and banks. Fast-moving rivers cause more erosion than slow-moving rivers. The Thames is a slow moving river.
Erosion shapes the land in different ways as the river moves from its source to its mouth.
Near the source of a river, in the upper course, erosion is vertical (downward). This is because the water is being pulled downwards by gravity. This forms deep V-shaped valleys.
The source of the Thames is not very high up and the land slopes away gently. It does not form deep V-shaped valleys but it does still cut through the land.
The photograph shows where, in the past, the river has formed a V-shape across the field near the source. The channel of the river starts in the bottom left hand corner and
Near the mouth of a river, in the lower course, erosion is lateral (horizontal or sideways). This forms a wide river channel.
Types of Erosion l Man and Erosion
Preventing Erosion l Evidence of Erosion
Start of Voyage down the Thames