Coastal Process Flashcards
Wave fetch
he distance of open water over which a wave has passed. Maximum fetch is the distance from one coastline to the next landmass, it often coincides with prevailing wind direction (South West in the UK).
Wave crest
Highest point of a wave.
Wave trough
Lowest point of a wave.
Wave height
Distance between trough and crest.
Wave length
Distance between one crest/trough and the next.
Swash
Water movement up a beach.
Backwash
Water movement down a beach
Abrasion/corrasion
When waves approach the coastline they are carrying material such as sand, shingle, pebbles and boulders. Abrasion occurs when this material is hurled against cliffs as waves hit them, wearing the cliff away.
Hydraulic pressure
Cliffs and rocks contain many lines of weakness in the form of joints and cracks. A parcel of air can become trapped/compressed in these cracks when water is thrown against it. The increase in pressure leads to a weakening/cracking of the rock.
Corrosion/solution
Seawater contains carbonic acid, which is capable of dissolving limestone. The evaporation of salts in seawater produces crystals and their formation can lead to the disintegration of rocks.
Sub-aerial
Coastal erosional processes that are not linked to the action of the sea. Erosion occurs via rain, weathering by wind and frost. Its impact is often seen in soil creep, slumping and landslides.
Human activity
Much building and recreation occurs at the coast, and this increases pressure on cliff tops, making them more liable to erosion and subsidence. The building of sea defences upsets the dynamic equilibrium of the coastline.
