3.2 Coastal Landforms Flashcards
What factors do affect waves?
They are energy that flow through water factors such as:
- Wind strength (stronger fetch)
- Wind duration (longer fetch)
- Water depth
- Fetch
What is a fetch?
Uninterrupted distance across water that wind blows.
What is a swash?
Flow of water up beach as wave breaks.
What is a backswash?
Flow of water down beach.
What are constructive waves?
- Depositional waves
- Low frequency
- Strong swash, weak backswash
- Low energy, low frequency
What are destructive waves?
- Erosional waves
- Larger fetch
- Weak swash, stronger backswash
- High energy, high frequency
What are subaeral processes?
Land-processes which can alter the coastline such weathering.
What is weathering?
The breakdown of rocks, with no movement.
What is mechanical weathering? (freeze-thaw)
Exertion of physical force of breaking material.
What is chemical weathering?
Chemical reaction with products that break down material. (acid rain)
What is biological weathering?
Plant/bacteria/animal action eg plant roots or overgrazing.
What is mass movement?
The sudden movement of large amounts of material typically rock and soil.
What is longshore drift?
Waves hit coast at prevailing wind angle, swash carries material up beach angle, backswash carries material down beach at 90 degrees.
What is a spit?
Longshore drift desposits sediment across a bay.
What is a Bar/Barrier beach?
Spit extends across bay, forms lagoon behind it.
What is a tombolo?
Bar connecting coast to offshore island.
What is a bayhead beach?
Sediment deposited into bay forming a beach.
What is a salt marsh?
Flat muddy coastal wetland on low energy coast.
What is an Offshore bar?
Destructive waves erode sediment which washes back into sea, forming bar parallel to coast.
What is a cupsate foreland?
Longshore drift occurs in opposite directions forming a triangular shape.
What is a sandy beach?
Flat stretch far inland, constructive waves, sand dunes.
What is a pebble beach?
Steep, short, far inland, destructive waves, large pebbles at back.
What is gravity settling?
When water energy is too low to transport sediment anymore.
What is flocculation?
Where small charged particles (eg clay) clump together + sink in the water.
What are the 4 types of sediment transportation?
- Traction: large boulders and pebbles are rolled alog the river bed.
- Saltation: small stones, pebble and slit bounces along the river bed.
- Suspension: Fine material such as clay and sediment us carried by the water.
- Solution: Dissolved minerals carried by the river.
What are the 4 erosional processes?
- Abrasion: rocks collide with cliff and wear it away.
- Attrition: peices of bedload collide with each other and get smaller
- Corrosion: *acids/chemicals dissolve certain rocks eg chalk, limestone
- Hydraulic Action: water is compressed into cracks in cliff which wears away.
What is a wave-cut notch?
Hydraulic action + abrasion erods the base of the cliff, creating a dent.
What is headlands and bays?
- Less resistant strat erode away - bays
- More resistant strata jut out - headlands
How does a wave-cut platform form?
Erosion of the wave cut notch will make the cliff collaose cliff retreats over time backswash carries the collapsed rocks away, forming a platform.
How does a coastal stump formed?
- Abrasion & Hydraulic action widen faults in headland which creates a cave.
- Over time, 2 back to back caves may break theough a headland creating an arch.
- The roof of the arch eventually collapses as it is unstable creating a stack.
- Stack erodes away turning into a stump.
