Deposition
Have you seen waves gently lapping at a sandy beach? Waves are part of the reason that beaches have sand. Ocean waves and current drop sand on a beach in a process called deposition.
Deposition is the dropping, or releasing, of sediments that have been moved from one place to another. Sand is sediment made from rocks or shells that have been ground into fine grains. |
Both erosion and deposition are gradual process. However, erosion is a destructive force, meaning that it wears down the land. Deposition is a constructive force, meaning it build up the land.
Deposition helps create a variety of surface features. Several of them occur as part of river systems. When a river moves across wide, flat regions, the river begins to wind in smooth curves called meanders. Meanders increase in size as water erodes the outside of each curve and deposits sediment on the inside.
Flooding of rivers on lowlands also deposits sediment. This sediment builds up on the flood plains.
When the flow of river water decreases quickly, special kinds of deposits are formed. An alluvial fan is a fan-shaped land mass that forms after a river rushes down a steep slope, then slows over a flat plain.
A delta is a low plain that forms where a river enters an ocean. If the river is large, the delta will be large, too.
Deposition helps create a variety of surface features. Several of them occur as part of river systems. When a river moves across wide, flat regions, the river begins to wind in smooth curves called meanders. Meanders increase in size as water erodes the outside of each curve and deposits sediment on the inside.
Flooding of rivers on lowlands also deposits sediment. This sediment builds up on the flood plains.
When the flow of river water decreases quickly, special kinds of deposits are formed. An alluvial fan is a fan-shaped land mass that forms after a river rushes down a steep slope, then slows over a flat plain.
A delta is a low plain that forms where a river enters an ocean. If the river is large, the delta will be large, too.