Topic 4 Flashcards
What is the rock type on a concordant coastline?
Only hard rock such limestone
Features of a concordant coastline are…
Cliffs and coves
Rock type on a discordant coastline is…
Repeating strips (strata) of hard then soft rock. At a right angle to the sea
Features of a discordant coastline
Headlands (hard rock) and bays (soft rock), arch stack stumps
Example of concordant coastline
Dorset Durlston head-kimmeridge
Example of discordant coastline
Dorset poole harbour-durlston head
What are joints and faults and how do they effect erosion
They’re weak points in the rock such as a crack and can speed up erosion through processes such as hydraulic action
Example of soft rock
Clay, sandstone, chalk
Examples of hard rock
Slate, granite, marble
Characteristics of headlands
Cliffy, rocky, no beach- waves crash into cliffs. Higher waves
Characteristics of bays
Lower energy waves, beaches, set further back than headland
Explain formation of headlands and bays
Strata of soft rock and hard rock parallel to sea waves. Waves continuously crashing in. Soft rock erodes back quicker than hard rock through processes such as abrasion, hydraulic action etc. Headland is formed when soft rock either side eroded backwards. Sediments fall from headland and end up on bay forming a beach
Characteristics of wave cut platforms
…
How are wave cut platforms formed
Intertidal area is eroded the most. Cliff becomes unsupported after rock below being eroded and overhangs the wave cut notch. Cliff then falls, retreats and the process begins again
Characteristics of arch stack stumps
Rocky,steep, high
How are arch stack stumps formed
Large weakness forms in rock. base of the crack erodes through hydraulic action. This gets larger and forms a cave. The cave forms an arch when it erodes through the headland. The arch keeps getting eroded until the roof is no longer supported. This forms a stack. This stack is eroded by waves until it tips over and firms a stump
3 factors that effect wave energy
Fetch, wind speed, gradient of seabed.
Where in the UK has the biggest wave
East coast and north coast of scotland because of very large fetch
Compare constructive and destructive for wavelength and frequency
Constructive have longer wave length and lower frequency than destructive
Compare con and destructive waves for swash and backwash
Constructive has more swash to transport sediments onto the beach and destructive has more backwash to take sediments away. Destructive have more erosional power
Explain rotational slumping
When the force of gravity is greater than the force holding it up the cliff collapses. Usually when lubricated by rainfall. A slump is when the cliff collapses through a rotational turn
Compare biological, freeze thaw and chemical weathering
Biological is naturally such as a plant putting its roots in a crack and expanding. Freeze thaw is the process of water entering cracks, expanding in cold temperatures as it freezes then melting and contracting again and chemical weathering is when rain is made slightly acidic which reacts with calcium in chalk and causes it to erode
Abrasion
When sediments get thrown against the cliff by waves constantly. Eventually chipping bits away
Hydraulic action
When salt water enters the cracks and the salt in the water expands and pushes the crack wider and wider multiple times until it cracks off
Attrition
Sediments in the waves crash into each other and become smaller and smoother
Solution
When sea water dissolves certain types of rock such as chalk
What is traction
Boulders rolling along the sea bed because they’re too heavy to be lifted by the waves
What is saltation
Small pebbles ‘bouncing’ along the sea bed
Suspension
Small pebbles essentially floating in the water being moved along by the wave energy
Solution
Really small sediments essentially float through the water without being seen
Explain LSD
Waves travel in the prevailing wind direction. These transport sediment which hit the coast at an angle through swash. They then return at a 90° angle through backwash. This is repeated
How are spits formed
They form at sharp curves in the coastline LSD transport sediments past the coast onto the sea. The sheltered area behind the spit are protected from waves
How does coastal management (building groynes for example) affect coastlines down drift?
It creates mass erosion to other beaches (bays) as the rock is deposited there
- How does agriculture affect the coastline
It could softer the land therefore is easier to erode/erodes easier
- How does industry affect the coastline?
Most of the sand is used to give height to industries therefore bays are much steeper, meaning waves are more destructive
- How does coastal management affect the coastline?
Groynes cause faster erosion and are very expensive. Which are also hard to maintain and they dig the sand from under the sea making the waves more powerful and destructive
