Case Study Overstrand Landforms Flashcards
Location?
North-east coastline in East Anglia, e.g. Overstrand
Waves?
Powerful and more destructive as they are built up over a large fetch: strong swash and weak backwash
Fetch?
3000km
Prevailing wind direction?
From the NE: waves hit cliff almost straight on- swash align beach and so erode rapidly
What is cliff made of?
Very weak: chalk bedrock is covered by a thick (2-5m) layer of glacial till which is unconsolidated so eroded easily
How do waves erode cliff and what do they create
Waves erode cliff by process of hydraulic action/pressure, abrasion and solution, creating a wave cut notch at the base of the cliff
What happens to cliff after being eroded?
Cliff collapse as unsupported cliff material slumps under its own weight - most common during heavy rains when cliff materials because saturated and very heavy.
What about other types of cliffs are there, what causes them?
Some are not very high or vertical because the unconsolidated glacial till collapses easily so they are instead gentle sloping and ave. 30m high - the underlying chalk is exposed in places
Erosional landform: Cliff retreat?
The cliffs retreat rapidly ave. 1m per year - a single powerful storm can erode hundreds of tonnes of material.
Erosional Landform: Wave cut notch visibility?
Wave-cut notch is only visible in some places because the unconsolidated glacial till collapses frequently, obscuring the notch.
Erosional Landform: wave cut platform (beach) description?
There is a gentle sloping wave cut platform in front of cliffs: left by rapid retreat of cliffs which is covered at high tide but exposed at low tide.
Erosion Landforms: wave cut platform (beach) coverage?
It is covered with a sandy beach: composed of slumped cliff material in process of being removed by longshore drift from the SE to the NW
Depositional landforms: Spit (Blakeney Point) waves?
Waves approach coastline at an angle: approach north-facing coastline from NE, which is the prevailing wind direction (drift align beach)
Depositional Landforms: spit (Blakeney point) longshore drift?
Long shore drift moves material EAST to WEST: waves move up beach at angle but returns at right angles due to gravity - material is moved along beach from east to west in process
Depositional Landform: spit (Blakeney Point) coastline?
Coastline changes direction as the coast bends SW as material being transported by longshore drift is deposited in the sheltered water where the coast changes direction.
Depositional Landforms: spit (Blakeney Point) finger of land, length & shingle?
Longshore drift from east to west provides more and more material deposited leading to finger of land being developed - Blakeney point is apx. 15KM long and shingle bank up to 10CM high
Depositional Landforms: spit (Blakeney point) curved ends?
Occasional storm winds from north and north west, forces the end of the spit to curve around - Blakeney point has at least 3 prominent curved ends
Depositional Landforms: salt marsh (Blakeney Marsh) wave energy?
Sheltered water behind the spit so wave energy is LOW
Depositional Landforms: salt marsh (Blakeney marsh) sediment?
This occurs in rivers such as the Stiffkey Freshes Creek as they empty into this area on the way to the sea - silt and other fine sediment that they are transporting is deposited in sheltered water
Depositional Landforms: salt marsh (Blakeney marsh) developing of salt marsh?
Over time silt builds up and plants able to colonise it e.g. spartina. The plants trap further sediment around their roots and stems and permanent marsh becomes established with +++ range of plants e.g. sea lavender, sea campion, samphire
Importance of Blakeney Marsh?
It has become an important international breeding are for sea bird colonies e.g. arctic terms, oyster catchers
