Coasts Flashcards
Define coastline
The point at which the land meets the sea
Define weathering
The breakdown of rocks at the earth’s surface, by the action of rainwater, extreme temperature and biological activity
Name the four causes of weather
- Biological
- Wind, rain and waves
- Freeze thaw
- Chemical weathering
Define fetch
The distance over which a wave forms
At what angle does the backwash go at
Right angles to the sea
At what angle does the swash go at
The angle of the wind
Define attrition
Material carried by the waves bump into each other and so are smoothed and broken down into smaller particles
Define hydraulic action
This process involves the force of the water against the coast. The waves enter cracks (faults) in the coastline and compress the air within the crack. When the waves retreats, the air in the crack expands quickly causing a minor explosion. This process is repeated continuously.
Define corrosion / solution
The chemical action of sea water. The acids in the salt slowly dissolve rocks on the coast.
Define abrasion / corrasion
The process where the coast is worn down by material carried by the waves. The waves throw the rocks / particles at the coast line.
List 5 reasons why some cliffs erode faster than others
Plant cover Rock type Weather conditions Wave energy (fetch, direction, prevailing wind) Wave type Wind speed Direction of wind Shape of coastline (sheltering) Chemical structure Freeze thaw
Define headland
Areas of resistant rock which protrude (stick out) from the coastline
Define bay
Areas of less resistant rock (soft) between two headlands which is quickly eroded
Define long shore drift (aka LSD)
The transportation of sediment along a stretch of coastline caused by waves approaching the beach at an angle
Define the solution transportation
Dissolved chemicals in sea water, carried along in solution
Define the suspension transportation
Small pebbles are carried in water
Define the saltation transportation
Loads bouncing and hopping along the sea bed
Define the traction transportation
Pebbles and larger sediment are rolled along the sea bed
When does deposition occur in the sea?
When the water has low energy and deposits the material it’s carrying
When is deposition likely to occur? (List 2-3)
When…
- waves enter shallow water eg bays
- waves enter a sheltered area where low energy means constructive waves are dominant
- there is little wind
- there is a wide expanse of flat beach so swash spreads out, weakening the wave so backwash is weak
- there is a good supply of material from updrift erosion
