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GCSE Geography course: Coastal landforms (Coastal Landforms (Soft rock:…
GCSE Geography course: Coastal landforms
Coastal terminology
Fetch:
The distance to the closest piece of land.
Long Shore Drift:
The process where material is moved along the beach when the prevailing wind hits the beach at an angle.
Destructive waves:
Strong backwash, waves close together with a steep front and a breaking wave that plunges downward.
Constructive waves:
Strong swash that adds to the beach, waves up to 1 meter high depositing material allowing transportation.
Weathering processes
Attrition:
rocks forced together smoothing; smaller and rounder.
Hydralic action:
waves trap air in cracks that widen them, weakening.
Solution:
rocks dissolve in salt: chalk + limestone
Mechanical weathering:
water gets trapped in rocks, freezing expanding and thawing breaking the rocks.
Salt weathering:
salt spray gets into the rock: - Some evaporates - Some will crystallise, breaking down the rock.
Chemical weathering:
When rainwater hits rocks it reacts. also includes Carbonation and Hydrolysis.
Mass movement:
heavy rainfall moves large amounts of soil or mud downslope, the scale is determined by the extent of weathering.
Slumping:
large areas of rock move down a slope on clay cliffs.
Coastal Landforms
Soft rock:
clay, sandstone.
Hard rock:
granite, slate.
Cordant:
Same type of rock along length. Rarely forms bays and headlands
Discordant:
The geology alternates between strata of Hard and soft rock.
The headland is worn away from a
Crack to a Cave, Arch, Stack, Stump
Sand dunes: Offshore bar, Beach berm, Incipient dune, fore dune, Hind dune
Depositional features:
beaches and sand dunes.
Deposition:
when the swash is stronger than the backwash
Spit:
a landform created of sand when the coastline changes direction aided by the process of LSD
CS: Lyme Regis Coastal Protection Scheme
It is built on some of the most unstable ground in the U.K. so a costal protection scheme was devised in 1990s to protect the town.
Phase 1: A new sea wall and promenade east of the river Lim. It was finished in 1995.
Phase 2: this will protect the foreshore and stabilise the land behind it. Work started in 2005 and costs £17m.
Phase 3: Never happened due to high cost.
Phase 4: Stabilised the homes, roads and infrastructure in 2015 at a cost of £19.5 million.
Coastal management types
Hard engineering
Sea wall: sends the wave back to sea.
Rock armour: reduce wave engergy
Gabions: absorb wave power to stop the waves from hitting the cliff
Groynes protect against the process of LSD
Soft engineering
Bach nourishment: extra sand is added to absorb wave energy
Dune regeneration: A natural barrier against the waves stabilization is cheap.
Managed retreat: natural processes are let allowed to happen as the land is cheap
For more visit:
https://www.bbc.com/education/clips/z397mp3