Deltas: Depositional Landforms
Depositional Landforms occurs if rocks and cliffs are being repeatedly weathered, eroded and moved then it stands to cause that this will make a lot of substance that will require being deposited (or laid down) somewhere else along the coastline.
Deltas are like alluvial fans but develop at a different location. The load carried by the rivers is dumped and spread into the sea. If this load is not carried away far into the sea or distributed along the coast, it spreads and accumulates as a low cone. When a river reaches a lake or the sea the water slows down and loses the power to carry sediment. The sediment is dropped at the mouth of the river. Some rivers drop so much sediment that waves and tides can’t carry it all away. It builds up in layers forming a delta.
Unlike in alluvial fans, the deposits making up deltas are very well sorted with clear stratification. The coarsest materials settle out first and the finer fractions like silts and clays are carried out into the sea. As the delta grows, the river distributaries continue to increase in length (Figure) and delta continues to build up into the sea.