How does moving water reshape the land?

Moving water can carry pieces of the landscape with it. Sunlight supplies energy for water to evaporate, and cooling lets water vapor condense into cloud droplets. Gravity brings rain toward the ground and draws runoff downhill. These changes supply streams with water that can pick up loose soil and sand.

The loose material carried by a river is called sediment. Flowing water pushes against grains and can move them from their resting places. Where flow no longer keeps them moving, some settle onto the bed. A river therefore transports material while also changing the ground along its route.

At many bends, erosion removes material from the outer bank while deposition adds it near the inner bank. Over time, this unequal removal and addition can shift the channel. A bank that looks fixed in one photograph may be part of a slowly changing landscape.

A mesh screen interrupts the journey of grains too large for its openings, while water and smaller particles can continue. Dissolved substances behave differently: their tiny dispersed particles can pass through an ordinary screen with the water. Following the material explains both how a river reshapes land and why separating a mixture depends on what is actually being carried.