depositional landforms

beaches

beach material consists of of sand, pebbles and cobbles coming from 3 main sources: cliff erosion, offshore (from seabed, typically during rising sea levels) and rivers (suspended and bedload through river mouths - about 90% of sediment)
sand creates beaches at a gentle gradient
- small particle size, compact when wet.
- material carried back down to beach as it is light.
shingle (pebble) beaches have a steeper gradientstorm beaches occur when storm waves throw pebbles and cobbles to the back of the beach, creating the steepest gradient.
- swash is stronger than backwash; leaving heavy shingle at the top of the beach, and dragging smaller sediment back to sea.
ridge - hump of sand created by wave action that runs parrallel to beach. berms are smaller ridges that develop at the tide line
beach profiles change over time as wind strength (and therefore wave energy) change.high energy, destructive waves create flatter beach profiles, whilst low energy, constructive waves form steeper profiles
- develop equilibrium - balance between erosion and deposition.

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long, narrow beaches of sand/shingle attached to land at one end and extend across body of water
formed by longshore drift occuring in one dominant direction - carries beach material past beach and into open water
end of spit often becomes curved due to wave refraction, or sometimes an opposing wave/wind direction
behind spit deposition occurs as wave energy is reduced, may lead to the formation of salt marshes - salt tolerant vegetation

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develop if a spit continues to grow across an indentation (meaning inward part of coastline such as bay or cove) and joins to land at other end
creates inland area of low energy water

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form on the inland side of spits, and estuaries
due to low-energy nature of environment, sediment is deposited and builds up
salt tolerant plant species grow too, such as eelgrass and spartina - help trap sediment and increase marsh height
flooded twice a day due to tide rise and fall, however the higher the marsh, less if it is submerged by sea water, meaning less saline conditions
closer to the spit, conditions for life in the marsh is poor and so diversity is low
further inland, the conditions less harsh and so diversity is greater
shallow gradient which slopes seawards
development of the marsh is dependent on how quickly sediment is deposited
rivers loose energy as they enter the sea, causing higher rates of deposition
flocculation - sediment particles group together to form flocs which are then heavy then deposited

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large areas of sediment found at the mouth of many rivers - sediment is deposited by rivers and tidal currents - form when rivers and tidal currents deposit sediment at faster rates then tides and waves can remove it. formed when:
- rivers enter sea carrying large sediment loads
- continental shelf margins (seabed which is much shallower than the rest of the ocean) is pre-existing, provides raised platform for sediment accumulation
- tidal ranges low
structures of delta:
- upper delta plain - furthest inland, composed of river deposits, out of reach to tides
- lower delta plain - in the inter-tidal zone (in the sea), regularly submerged and made from both marine and river deposits
- submerged delta plain - lies below water (submerged) and made from marine deposits
3 most common types of delta:
- cuspate - pointed shape, caused by gentle currents from opposite directions moving sediment
- arcuate - wider, rounded shape. grows seawards due to plent of sediment, wave action keeps edges rounded
- bird's foot - branching pattern formed by distributaries, river sediment supply exceeds waves and currents

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