Deposition
Waves are a part of the reason that beaches have sand. Ocean waves drop sand on a beach. Sand is sediment made from rocks and shells that have been ground into fine grains. This dropping of sediment is called deposition. Deposition is the dropping, or releasing, of sediments that have moved from one place to another. Both erosion and deposition happen slowly, over time. Erosion is a destructive force. This means that it wears down the land. Deposition is a constructive force. This means it builds up the land.
Deposition helps form a number of surface features. Several of these features form as part of river systems. A river usually begins at a high point on Earth's surface. At first the water flows quickly downhill and carries sediment with it. At the mouth, or end of the river, the water usually empties into a large body of water, such as a lake or ocean.
Waves are a part of the reason that beaches have sand. Ocean waves drop sand on a beach. Sand is sediment made from rocks and shells that have been ground into fine grains. This dropping of sediment is called deposition. Deposition is the dropping, or releasing, of sediments that have moved from one place to another. Both erosion and deposition happen slowly, over time. Erosion is a destructive force. This means that it wears down the land. Deposition is a constructive force. This means it builds up the land.
Deposition helps form a number of surface features. Several of these features form as part of river systems. A river usually begins at a high point on Earth's surface. At first the water flows quickly downhill and carries sediment with it. At the mouth, or end of the river, the water usually empties into a large body of water, such as a lake or ocean.
Near the mouth, the land is flatter. Water flows more slowly over flat land. The sediment drops out of the water. A delta is a low plain that forms where a river enters an ocean.
Sometimes a river rushes down a steep slope, then slows over a flat plain.There, a fan-shaped deposit called an alluvial fan forms.
Sometimes a river rushes down a steep slope, then slows over a flat plain.There, a fan-shaped deposit called an alluvial fan forms.