Coastal Terminology Flashcards
Abrasion
Sand grains, and rocks in the waves wearing away the coastal rock.
Anti-clockwise rotation
rotation of wind in hurricane in Northern Hemisphere
Atoll
A coral island consisting of a reef surrounding a lagoon (e.g. Maldives)
Attrition
Rocks on the ocean floor constantly collide with each other and break down in size… eventually becoming sand.
Backwash
When a wave breaks, water is washed up the beach. This is called the swash. Then the water runs back down the beach, which is called the backwash. With a constructive wave, the swash is stronger than the backwash. With a destructive wave, the backwash is stronger than the swash.
Barrier reef
A coral reef that is separated by the mainland by a deep channel or lagoon (e.g. Great Barrier Reef, Australia)
Bays and headlands
Bays are created by wave refraction (bow shape) around a headland and headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock. This leaves a section of land sticking out into the sea called a headland.
Blow hole
Formed as sea caves grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in blasts of water from the top of the blowhole.
Blow out
Blowouts are caused by eddy currents between sand dunes, which can then create a dune slack, typically below the water table so a pond of sorts is formed.
Bomb-fishing
Fishermen bait fish with chum above coral reefs and drop home made bombs in the water stunning and killing fish to capture but also destroying coral reefs
Boulder clay (till)
An unsorted mixture of sand, clay and boulders carried by a glacier and deposited as ground moraine over a large area. It is difficult to build on it and it erodes fast.
Broomhill Burrows
Example of a sand dune (situated in Pembrokeshire, Wales), heavily populated by rabbits who feed on plant shoots, maintaining a state of plagio-climax
Calcium carbonate
The substance most organisms in the ocean make their sheels/skeletons out of (alkaline)
Cliff-regrading
Restructuring the face of a cliff to make the gradient less steep (soft engineering). Sometimes used to decrease cliff-retreating.
Cliff-retreating
When the wave-cut notch gets deeper and deeper and finally the part of the cliff closest to the water collapses and the whole process continues, causing the cliff to retreat
Coastal bar
When a spit builds up so much that it covers the entrance to a bay creating a lagoon. An example of this is Loe beach in Cornwall.
Constructive waves
They have a powerful swash and a weak backwash, and wave length long in relation to wave height. Created in calm conditions (light wind), less powerful than destructive waves and break on the shore, depositing material, building the beach. 9 waves or less per minute
Coral bleaching
A process whereby the coral colonies lose their colour, exposing the calcium carbonate skeleton due to the expulsion of the zooxanthellae under stressful conditions (e.g. when temperature is too high)
Coral reef
Colony of coral typically found 30° N or S of equator, in warm, shallow, tidal and clear waters.
Corrosion
Certain acids in sea water can have a chemical reaction with some rocks. The rock is eaten into creating a ‘honeycombing’ effect.
Crest and trough
The crest is the highest point on the wave above the still-water line. A trough is the opposite of a crest, so the minimum or lowest point below the still-water line. To measure the wave height, you measure the vertical distance between crest and trough.
Cyanide fishing
The process of fishing aquarium fish with cyanide, a chemical poison, to stun them
Deposition
When silt or other material that has been eroded is deposited, sometimes causing a spur head to be formed
Destructive waves
Destructive waves are created in storm conditions. They are created from big, strong waves when the wind is powerful and has been blowing for a long time. They occur when wave energy is high and the wave has travelled over a long fetch. They tend to erode the coast. They have a stronger backwash than swash. Wave height big in relation to wave length. 11 or more per minute.
‘Do nothing’
The easy/cheap option, deal with the effects of flooding and erosion. Do nothing as there are no people living there or the government doesn’t have the money
Dune slack
Dune slacks are low-lying areas within dune systems that are seasonally flooded and where nutrient levels are low.
Dynamite fishing
A fishing method that involves a stick of dynamite; the dynamite stuns the fish, making them float and easy to collect
Easington Gas Works
Very valuable gas company that processes natural resources found in Norwegian seas. Protected by “hold the line” built in 2008, consisting of a rock revetment and regrading at the base of the cliff
Embryo dune
The original and first seral stage of a sand dune, sand builds up on and around obstacle