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Deltas
Question | Answer |
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Define a delta | A delta is a group of triangular tracts of land found at the mouth of a river when it begins to deposit its load. |
What is a bottom set bed | horizantal layers of very fine clay and silt These sediments are very fine and are transported far out to sea before settling |
explain flocculation | when river water mixes with sea water the reaction between the silt and the salt causes the particles to stick together and coagulate which causes them to sink to the bottom |
foreset beds | Thick layers of coarser material which settles on the bottom set beds closer to the mouth of the river |
topset beds | mixture of material deposited ontop of the foreset beds close to the land, this builds up above the high-water level |
distributaries | RIver nouth becomes choked so the river is forced to break up the alluvial deposits with smaller chanels forming the delta. |
Arcuate delta | deltas that form in areas with strong currents and that have a large number of distrubutaries |
Birds Foot Delta | Thin deltas extending far into the sea with not many distributaries, shaped like a birds foot |
Estuarine Delta | A delta that has not yet extended past the coastline where sediments have been deposited along the shallow parts of the coastline |
Where do deltas form | Old age stage of the river is it enter the sea where the process of deposition is stronger than the process of erosion of the body of water is is entering |
Why do deltas form | When rivers carry a large bedload - eroded material carried along by a river - and it loses velocity as it enters the sea, it no longer has the enrgy to carry the load and it is deposisted |
Types of SEAS | Seas like the Mediterranean have a small tidal range and clamer water allowing for the growth pf deltas |
Example of an arcuate delta | EG) The Nile Delta |
EG of an estuarine delta | The Mouth of the river RHine |
EG of an estuarine Delta | The Mississippi Delta |