Coastal

• Constructive waves


  Powerful wave with a strong swash that powers up the beach;deposit
• Destructive waves


  A wave caused by storm, crashes on a beach,strong backwash;destroy
• Transportation

  Suspension-Fine material; clay and sediment

  Solution-Dissolved minerals carried by sea

  Traction-Large boulders and pebbles rolled on sea bed

  Saltation- small stones and pebbles that bounces along sea bed
• Erosion; Hydraulic action


  The force of waves pushes air into cracks at massive pressures

  The pressure upon the crock is at greatest at stormy conditions

  Compressed air under the great pressures force out parts of cliff face
• Erosion; Wave pounding

  Shock waves bash against the rock face breaking off pieces off rock

  Assists in the weakening of rock faces and create openings for hydraulic action to take place

  It also provides rock debris for Abrasion
• Erosion; Abrasion


  Takes place at base of cliff

  When sand and rocks are thrown against the cliff face by waves

  They scrape away rocks over time and undercut base of cliff
• Erosion; Solution

  Soluble minerals in rocks are dissolved in water; used to chemically weather rock face

  Solution can take place above high water line as when the water hits the cliff the spray reaches higher heights

  Carbon dioxide in the atmosphere gets dissolved in seawater making carbonic acid which erodes rock EG. White cliffs of dover
• Erosion; Attrition


  When rocks have broken off the rock face due to [HA, WP]

  These rocks collides with rock face making them smaller and rounder

  Small rocks mean waves can more easily carry material=further erosion

  It aids the process of abrasion
• Longshore drift


  Waves move towards coast at an angle[The angle of prevailing wind]

  Swash reaches coast at angle and the backwash leaves perpendicular

  The material deposited on the beach follows a zig-zag motion until it reaches end of the beach

  It deposits material in the water until enough material is deposited and breaks the waters surface

  This is how LD grows a non-static and non-permanent beach a non-static and non-permanent beach

  Other features such as sand spit, sandbars and tombolos come from LD
• Sandspit; EG. Mouth of Tay river


  LD- Prevailing wind carries material by longshore drift. Material builds up/outwards forming spit. Occasionally wind blows at different direction=some material pushed inland=end spit to curve. Coastline change direction, sand/shingle deposited in water sheltered by headland.Wind returns to usual direction=spit continues grow outwards. Further curved ends formed as wind direction change. Spit cannot grow across estuary due to speed of river carrying material to sea. This line marks OG position of coastline. Salt marsh form in the sheltered water behind the spit
• Sandbar


  Prevailing wind carries material by longshore drift. Material builds up and outwards forming a spit.

  When a sanspit joins one headland to another a sandbar Is formed

  This barrier of sand/shingles which stretches across a sheltered bay

  This can form a lagoon or marsh to the landward side

  EG. Slapton sands
• Tombolo

  Prevailing wind carries material by longshore drift. Material builds up and outwards forming a spit.

  When LD continues to deposit material past the coastline and turning point it can reach another piece of land

  When a sandspit joins a headland to an island=tombolo
• Headlands and Bays

  Destructive waves=high energy+short fetch formed in storm conditions

  They attack weakest point of coastline; crack

  H+B formed along concordant and discordant coastlines, most common on discordant where alternate bands of hard/soft rock are found at right angle to coast.

  Formed by differential erosion, where less resistant rocks erode more quickly than harder rocks
• Headlands and Bays Pt.2

  HA; Waves compress trapped air in rocks, creating explosive blast which weakens/loosens rock fragments

  Abrasion; rock fragments thrown against headland creating sandpaper action

  Solution carbonic acid in sea water weather limestone and chalk

  Attrition can occur here, rock fragments slowly ground down by friction from wave action into small/round pieces to form sand

  A headland is an area od hard rock which juts out into the sea and a bay is a sheltered are of soft rock between the headlands EG.Sinclair Bay
• Cliff and wave cut platform


  Weathering happens at top of cliff breaking rock parts away

  Between high and low water mark processes of HA, Abrasion, solution erode the base of the cliff

  HA;Waves compress trapped air in rocks creating explosive blast which weakens/loosens rock fragments

  Abrasion;Rock fragments thrown against cliff creating sandpaper action

  Solution;Carbonic acid in seawater weathers limestone and chalk
• Cliff and wave cut platform Pt.2

  Due to processes of erosion,cliff becomes undercut and protruding cliff is unstable

  Due to gravity/continued erosion cliff will eventually collapse into sea

  The process repeats and the cliff retreats inland

  A wave-cut platform is left behind, at the low tide level; as there is less erosion at that point

  EG. East Caithness Cliffs
• Arches, Stacks, and stumps

  Due to erosion of headland cracks open up

  The erosional processes of HA, Abrasion and solution the cracks are eroded deeper into the headland forming a sea cave.

  With repeated erosion on both sides of the headland the sea cave breaks through forming a natural arch, it can also be due to wave refraction around headland.
• Arches, Stacks, and Stumps Pt.2

  HA;Waves compress trapped air in rocks creating explosive blast which weakens/loosens rock fragments

  Abrasion;rock fragments thrown against headland creating sandpaper action.

  Solution;Carbonic acid in seawater weathers limestone and chalk.

  Rock material at top of arch is weathered/eroded further by solution weakening structure
• Arches, Stacks, and Stumps Pt.3

  Due to erosion/gravity arch roof collapses leaving tall isolated stack.

  Continued undercutting of stack will cause it collapse into sea=stump.Stumps eroded due to wave pounding, eventually disappear.

  Wave pounding; waves smash into rock face breaking pieces off

  EG. The whales mouth, moray
• Longshore drift diagram

  A) Prevailing wind

  B) Non Static beach

  
• Cliffs and wave cut platform

  A) Gravity

  B) Unstable

  C) Undercut

  D) Retreat inland

  E) HA, Solution,Abrasion

  F) erosion

  
• Headlands and Bays

  A) Discordant

  B) chalk

  C) clay

  D) Differential erosion