Coastal Transportation and Deposition Flashcards
Longshore drift
Waves follow the direction of prevailing wind. They hit the coast at some angle. The swash carries material up the beach in the same direction as the waves. The backwash then carries material down the beach at right angle.
Traction
Large particles like boulders are pushed along the sea bed by the force of water.
Suspension
Small particles like silt and clay are carried along in the water.
Saltation
Pebble-sized particles are bounced along the sea bed by the force of the water.
Solution
Soluble materials dissolve in the water and are carried along.
Constructive waves
- low wave in proportion to length
- strong swash and weak backwash
- deposit sediment on the beach
Destructive waves
- high wave in proportion to length
- a tall breaker it breaks downwards with great force
- weak swash
- strong backwash
Sand beaches
Flat and wide-sand particles are small and the weak backwash can move them back down the beach, creating a long, gentle slope.
Shingle beaches
Steep and narrow-shingle particles are large and the weak backwash cannot move them back down the beach. They has a steep slope.
Spits
- form at sharp bends in the coastline
- longshore drift transports sand deposit it in the sea
- strong winds or waves can curve the end of the spit
- the sheltered area behind the spit is protected from waves-lots of deposition takes place there(formation of mud flat or salt marsh)
Bars
- formed when a spit joins two headlands together
- the bar cuts off the bay
- lagoon can form behind the bar
Sand dunes
- formed when sand on the beach is moved by the wind
- obstacles cause wind speed decrease so sand is deposited
- this sand is colonized by plants and grass. The vegetation stabilize the sand and encourages more sand to be deposited
