Rivers & Deltas
Sediment in rivers gets deposited as the river slows down. Larger, heavier particles like pebbles and sand are deposited first, whilst the lighter silt and clay only settle if the water is almost still.
The flow of water is strongest on the outside of river bends, eroding the bank, but is slowest on the inside of the bends, allowing deposition of sand and gravel.
When a river “bursts its banks” after heavy rain, flood water spreads out across the floodplain and, because this water hardly moves, finer silt and clay are deposited – often making good farmland!
The flow of water is strongest on the outside of river bends, eroding the bank, but is slowest on the inside of the bends, allowing deposition of sand and gravel.
When a river “bursts its banks” after heavy rain, flood water spreads out across the floodplain and, because this water hardly moves, finer silt and clay are deposited – often making good farmland!
L Immoor: www.geoteach.com
© NASA - NSSDC
When a river reaches a lake or the sea, it quickly deposits much of its sediment. This may choke up the river channel, which then divides up into distributaries, between which swamps are formed.Over time, sediment deposition may build up a delta like those of the river Nile in Africa (see satellite picture) or the Mississippi (USA).
