Coastal Processes Flashcards
Abrasion
The process by which the coast is worn down by material carried by the waves. Waves throw these particles against the rock, sometimes at high velocity.
Attrition
Material carried by the waves bump into each other and so are smoothed and broken down into smaller particles.
Backwash
The motion of receding waves (water runs back down the beach).
Corrosion
Chemical action of sea water. Acids in salt water slowly dissolve rocks on the coast. Limestone and chalk are particularly prone to this process.
Hydraulic Action
This process involves the force of water against the coast. Waves enter cracks (faults) in the coastline and compress air within the crack. When the wave retreats, the air in the crack expands quickly causing a minor explosion (cavitation). This process is repeated continuously.
Longshore Drift
Net effect of movement of sediment up and down the beach to the shore. Waves approach the beach at an angle in the same direction as prevailing winds and, as the waves advance, material is carried up the beach at an angle. Backwash pulls material down the beach at right angles to the shore under gravity. The process repeats along the shore.
Saltation
The transport of hard particles over an uneven surface in a turbulent flow of air or water (bouncing across the seabed).
Suspension
Fine light material is carried along in the water.
Swash
When water is washed up the beach after an incoming wave has broken.
Traction
Large boulders and rocks are rolled along the river bed.
Coastal Recession
Another term for coastal erosion (the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage, or high winds)
Dynamic Equilibrium (sediment cells)
State of balance between continuing processes, inputs, and outputs.
Eustatic change
Sea level change due to an alteration in the volume of water in the ocean or a change in the geometry of the ocean basins which alters the volume of water they can hold. It is always a global effect.
Isostatic change
Sea level change due to an alteration in the level of land, due to tectonic activity or the removal of great weight from the land (e.g. melting ice cap). It is a local effect.
Plant succession
The changing of plant communities over time (the process of one plant community gradually or rapidly replacing another).