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Wave Erosion
geo terms
| Term | Definition |
|---|---|
| Coast | Intermediate zone of contact bewteen land and sea |
| Coastline | Margin of the land. Marks the seaward limit of the permanent exposed coast. |
| shore | area between lowest and highest water levels |
| cliff line | same as coast line but along rocky coast |
| fetch | distance of open water over which the wind blows |
| swash | water thrown up the beach by breaking waves |
| backwash | term for water that drains back down the beach |
| beach | deposition of sand, pebbles, and boulders along the coast |
| constructive waves | swash more powerful than backwash-has force of the breaking wave behind it. When waves break at a rate of ten or less a minute, each breaking wave is able to run its course withour interference form the one behind it, and sand and pebbles are deposited. |
| destructive waves | when waves break more frequently (more than 15/min),backwash of a wave runs into swash of wave behind it. The force of the swash is therefore reduced in comparison with the force of the backwash-destructive waves remove sand and pebbles from a coast. |
| wave erosion 3 parts Part A | 3parts:a)corrosive action(boulders, pebbles, and sand hurled against cliff base causing undercutting and rock breakup |
| wave erosion Part B | b)hydrolic action (water thrown against cliff face by breaking waves causes air in cracks/crevices to become suddenly compressed-when wave retreats, air expands explosively-rock shatters |
| wave erosion Part C | c)attrition (boulders/pebbles dashed against shore, then broken into finer particles |
| notch and cliff | Part 1:notch found along coast w/ smooth sloping land;destructive waves Part 2: wave hits coast; undercuts contact zone, forms low cliff (notch)Part 3: further undercutting at base; collapse of notch roof Part 4: forms higher free face called a sea cliff |
| wave cut platforms | platform is under sea water during high tide; above during low tide; has a flat bare rock surface with a cliff behind. deposition is rare on the platform. |
| Formation Parts 1-4 | Part 1: Destructive waves quickly erode sloping coast Part 2: waves undercut base of slope forming a notch Part 3: whne notch is deeply undercut, upper part no longer being supported Part 4: notch collapses-cliff is formed |
| Formation Part 5-8 | Part 5; further abrasion caused cliff to retreat Part 6: landslides on cliffs are common and help rate of retreat Part 7: materials derived from cliff retreat removed by waves Part 8:bench like surface formed in front of cliff is wave life platform |
| caves | cave grows along line of weakness at cliff base subjected to prolonged wave; cylindrical tunnel extends into cliff, follows line of weakness; diameter decreases from entrance; if joint extends from end of tunnel to cliff top,becomes enlarged; forms blowho |
| arches | roof of cave collapses; long narrow sea inlet forms a geo. caves which develop on either side of headland and eventually join together, give rise to a natural arch. |
| stacks | when arch collapses, the end of headland stands up as a stack( offsore or sea stack) |
| wave transport Parts 1-4 of 8 | 1:LOAD=all material carried by breaking waves 2:Load= mud, sand, shingle 3:when waves break obliquely to the shore, the swash moves obliquely up the shore, but the backwash moves back at right angles to the shore 4: material is carried along beach |
| wave transport Parts 5-8 of 8 | 5: these two actions together constitute long shore drift 6: removal of material by long shore drift can be stopped by building groynes or walls out to sea 7:material also carried offshore into deeper water by undertow 8:erosion dominant on lowland coast |
| Features Produced by wave Deposition a) Beach 1-4 of 7 | 1. Main action of constructive waves is to deposit pebbles, sand and mud. 2. When deposited along coast, they form a gently sloping platform called beach. 3. The material a beach is composed is transported along coast by longshore drift 4. Wave action |
| Features Produced by wave Deposition Beach 5-7 of 7 | 5. Beaches called bay-head beaches develop at the heads of bays. 6. These beaches do not extend to the headlands where wave erosion is dominant. 7. Examples - east coast of Peninsular Malaysia |
| Features Produced by wave Deposition b) Spit 1-3 of 10 | 1. Material which is eroded from a coast may be carried along the coast by longshore drift. 2. Deposited further along the coast as a spit. 3. Likely yo happen along indented coasts broken by river mouths. |
| Features Produced by wave Deposition Spit 4-5 of 10 | 4. A spit is a low, narrow ridge of pebbles or sand joined by the land at one end with the other end terminating in the sea. 5. A spit can sometimes develops at the headland and projects across a bay. |
| Features Produced by wave Deposition Spit 6-8 of 10 | 6. As waves swing into a bay obliquely, the end of spit becomes curved. 7. When longshore drift operates across a rivers mouth a zone of slack water develops between longshore drift and the river. 8. Any material carried by Longshore drift is deposited |
| Features Produced by wave Deposition Spit 9-10 of 10 | 9. The deposited material forms a spit, which may, in time, extend across the mouth of the river. 10. When this happens the river's outlet may be diverted, or the river's mouth may be converted into a lagoon. |
| Bar C) 1-4 of 8 | 1. Similar to spit 2. Common type of bar is that which extends right across a bay. 3. Starts as a spit growing out from a headland. 4. Ultimately stretches across the bay to the next headland - bay bar. |
| Bar C) 1-4 of 8 | 5. Many bay bars have breaks in them. When a bar joins an island to the mainland it is called a tombolo. 7. Chesil Beach, Southern England is a good example of a tombolo. 8. Off-shore bars develop only along very gently sloping coasts. |
| Bar C) 8 of 8 | Off-shore bars develop only along very gently sloping coasts. |
| Mud Flats D) 1-2 of 5 | 1.Tides tend to deposit fin silts along gently shelving coasts, especially in bays and estuaries. 2. The deposition of these slits together with river alluvium, results in the building up of a platform of mud called mud flats. |
| Mud Flats D) 3-5 of 5 | 3. Salt tolerant plants soon begin to colonise the flat. 4. The mud flat in time becomes a swamp or marshland. 5. In tropical regions, mud flats often become mangrove swamps. |
| Ria Coast 1-3 of 5 | 1. When a highland coast is submerged the lower parts of its river valleys become flooded. 2. ias lie at right angles to the coastline. 3. Common in SW Ireland, SW England. |
| Ria Coast 4-5 of 5 | 4. Due to the submergence the coast becomes indented. Tips of headlands may be turned into islands. |
| Longitudinal Coast 1-4 of 4 | 1. Highland coast whose valleys are parallel to coast is submerged. 2. Some of the valleys are flooded. Separated mountain ranges become chains of islands. |
| Longitudinal Coast 1-4 of 4 | 3. These valleys are sometimes called sounds e.g. puget sound in Washington. 4. This type of coast occurs in Yugoslavia. |
| Fjord Coast 1-3 of 7 | 1. Glaciated highland coasts become submergerged. They are at right angles to the coast. 2. The flooded lower parts of the valley are called fjords. 3. During glaciation the river valleys become widened and deepened. |
| Fjord Coast 4-5 of 7 | 4. After the glaciers have disappeared and the sea has risen the steed-sided valleys are drowned. The water inside the fjord os much deeper than it is at the entrance. 5. Fjords have steeper sides and deeper water than rias. |
| Fjord Coast 6-7 of 7 | 6. Small rocky islands, skerries, may occur at entrance. 7. Fjord coasts - South island of New Zealand, Norway, British Columbia. |
| value of Rias and Fjords to man 1-3 of 4 | 1. Provide natural harbours. 2. Difficult to get inland from the head of a fjord because of mountainous country not useful as a port. 3. Easy to get inland from the head of a ria - good port site. |
| value of Rias and Fjords to man 4 of 4 | 4. Fjord settlements occur at the head of the fjord where there is level land. |
| Submerged Lowland Coasts B) 1-3 of 3 | 1. The rise in sea level along a lowland coast causes the sea to penetrate inland along the river valley. 2. The flooded parts of the valley are called estuaries. 3. Baltic coasts of Poland and Germany and the Dutch coast are examples. |
| Emerged highland Coasts C) 1-2 of 4 | 1. An Old sea beach blacked by a sea cliff from 7.5-30 m above sea level often characterises this type of coast. These two features could only have been produced by sea action. |
| Emerged highland Coasts C) 3-4 of 4 | 3. Since the sea no longer reaches them, it is evident that there has been a change in either sea level or the level of land. 4. Raised beaches are common in western Scotland. 4. |
| Emerged Lowland Coasts D) 1-3 of 5 | 1.Forms when a part of the continental shelf emerges from the sea and forms a coastal plain. 2. the coast has no bays or headlands. 3. Deposition takes place in the shallow water off-shore, producing off-shore bars, lagoons, spits and beaches. |
| Emerged Lowland Coasts D) 3-5 of 5 | 4. Examples - S.E. coast of the US, N. coast of the Gulf of Mexico. 5. Development of ports is difficult. |
Created by:
kevintutty
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