Erosion by Streams - II

Streams that start in the mountains rush down steep slopes, carrying rocks and sediment. The powerful water erodes the streambed, carving deep into the land and creating a narrow, V-shaped valley.

When a stream flows from an area of harder to softer rock, it erodes the softer rock more quickly. This makes the riverbed drop suddenly, like a step, creating a waterfall. As the water continues to flow, the waterfall gradually moves upstream.

As streams leave the mountains and reach flatter land, they slow down. Instead of cutting deep into the land, the water erodes the outside of curves where the speed of the water is high. It also deposits the eroded material on the inside, forming large, looping curves called meanders.

When meanders erode from side to side, they create a floodplain, a flat area around a stream where water flows when the stream floods.

Sometimes, a meander becomes so curved that it is cut off from the river, forming an oxbow lake.