Coastal Revision Notes


1. Arch:-
When caves, which have developed on either side of a headland, join together they form a natural arch.
2. Attrition:-
The process whereby rock particles wear down through collisions with other rock particles. This often occurs when pebbles are thrown against cliffs, boulders or other pebbles, causing them to shatter and break.
3. Backwash:-
Water moves up a beach as a wave breaks. This is called the swash. The return movement of the water, back down the beach, is called the backwash.
4. Bar:-
A bar is very similar to a spit. It is a ridge of sand or shingle which forms across the mouth of a river, the entrance to a bay or harbour. It is usually parallel to the coast.
5. Bay:-
A wide indentation into the land by the sea, protected on each side by a headland. The water in a bay is usually relatively shallow; the wave action less strong than at the headlands.
6. Bay-bar:-
A bar across the entrance of a bay.
7. Bay-head beach:-
Bay head beaches develop at the head, or inner most part, of a bay. In this area wave action is usually not very strong and deposition occurs. The beach will not extend to the headlands since erosion from waves increases strongly towards the headlands and deeper water.
8. Beach:-
A gently sloping deposit of sand, pebbles or mud, deposited along the coast.
9. Blow hole:-
A blow hole is formed when a joint between a sea cave and the land surface above the cave becomes enlarged and air can pass through it. As water flows into the cave, air is expelled through the pipe like joint, sometimes producing an impressive blast of air or spray which appears to emanate from the ground.
10. Cave:-
A weakness, such as a joint, is enlarged by wave action, finally creating a cylindrical tunnel which follows the line of weakness. Caves developing back to back may give rise to arches and stacks.
11. Cliff:-
A steep, and usually high, rock face found at the edge of the land where it meets the sea. Cliffs can be formed from most rocks, height generally increasing with hardness of rock.
12. Cliff Line:-
The margin of the land. The cliff line is identical to the coastline, but consists of cliffs rather than lower features such as dunes and beaches.
13. Coastline:-
The margin of the land. Where the margin consists of cliffs, it is known as the Cliff line
14. Constructive wave:-
When waves break at a rate of ten or less per minute each wave is able to run up the beach and drain back again before the next wave arrives. The swash is more powerful than the backwash so deposition can occur.
15. Corrasive action:-
This is a form of wave erosion. Pebbles, boulders and rocks are thrown against the cliff face by breaking waves. This causes undercutting of the cliff and leads to the breakup of both the cliff and the objects being thrown against it.
16. Destructive wave:-
When waves break at a rate of more than ten per minute each wave is able to run up the beach but unable to drain back again before the next wave arrives. Thus the backwash of the previous wave interferes with the swash, reducing it’s efficiency. Such waves remove material from a beach and are destructive.
17. Emerged coast:-
Coastal areas which have become raised above current sea level. The cause is believed to be isostatic adjustment.
18. Estuary:-
The mouth of a river where fresh water and sea water mix, and tides have an effect. Estuaries are often to be found on submerged coastlines, where a river valley has been flooded by the sea. See ria.
19. Fetch:-
This distance of open water over which the wind can blow and form waves.
20. Fiord Coast:-
When a glaciated coast, with deep valleys, becomes flooded by the sea, the valleys are known as fiords. These inlets are typically steep sided and deep.
21. Headland:-
Areas of harder rocks tend to resist the erosive powers of the sea. The resulting area of land, jutting out into the sea, is a headland. Bays are to be found between headlands.
22. Hydraulic action:-
When a wave breaks against a cliff it causes air ,trapped within cracks, to suddenly become compressed. As the water retreats the air is allowed to expand, often explosively. Repeated expansion and contraction of the cracks leads to the break up of the surrounding rock.
23. Lagoon:-
When a spit extends across the mouth of a river, to the extent that it causes the river to become diverted along the coast, an area of water is created separated from the sea by a narrow strip of land. This is a lagoon.
24. Load:-
Solid matter carried by water, including material in solution, material suspended in the water, and larger material moved along the water / ground interface.
25. Longitudinal Coast:-
These occur when valleys parallel to the coast become flooded by the sea. As the land becomes submerged, the ridges of land between the valleys become chains of islands parallel to the new coast. The area of water between the island chains are sometimes referred to as sounds.
26. Longshore Drift:-
When waves break on to a beach at an angle, material is pushed up the beach at an angle by the swash, but pulled back down the beach by the backwash at ninety degrees to the coast. In consequence, material is slowly moved along the coast, in the direction of the waves.
27. Mud Flats:-
Gently sloping coasts where fine sediments can settle, perhaps together with river sediments, can allow the build up of mud as a sheet known as a mudflat. Plants able to withstand salt water will often colonise the area. In tropical areas this may lead to the formation of mangrove swamps.
28. Ria:-
When a non-glaciated highland coast becomes submerged, the valleys fill with sea water. As the area becomes flooded the coast becomes indented and higher parts of the surrounding land may become islands. Plymouth Sound and Southampton Water are examples of rias in the United Kingdom.
29. Sound:-
Valleys flooded due to submergence under the sea along a longitudinal coast are sometimes called Sounds.
30. Spit:-
Longshore Drift transports material along the coast. When the mouth of a river, or an indented area, is encountered material starts to be deposited. The deposition begins where the coast changes direction and extends down coast in the direction of longshore drift. The result is a narrow ridge of material ( sand or pebbles ) attached to the mainland at one end and terminating in the sea. The spit may extend sufficiently to form a lagoon.
31. Stack:-
When a natural arch collapses, the remaining upright sections form stacks, isolated rocks sticking up out of the sea.
32. Storm beach:-
A ridge of material to the landward side of the normal beach. During storm conditions the waves may have sufficient power to throw material beyond the usual range ( between high and low water marks ). Such material will remain in place for a considerable time, being added to by subsequent violent storms.
33. Submerged coast:-
Coastal areas which have become lowered below current sea level. The cause is almost always a rise in sea level in consequence of ice melting since the last ice age.
34. Swash:-
The movement of water in a breaking wave as it moves up the beach.
35. Tides:-
The daily movements of the sea as it covers and exposes the area between February 24, 2006 ult of lunar activity, and to a much lesser degree, winds and atmospheric pressure.
36. Tombolo:-
A bar linking an island to the mainland.
Undertow
A current taking water away from the beach and out into deeper water. The undertow prevents the build up of water from breaking waves along the coast.
37. Wave-cut Platform
As cliffs become eroded down to beach level they appear to migrate inland. The remains of the former cliffs form a flat rock platform. This is known as a wave cut platform.
***Mission Geography***

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