Enquiry Questions 1 and 2: Processes and Landforms Flashcards
beach system
input - sediment from longshore drift. Throughput/transfer - longshore drift.
Output - longshore drift and destructive waves.
Cliff System
Input - sub-aerial weathering.
Throughput/transfer - mass movement and slumping.
Output - removal of material at base of cliff.
Mass movement
The movement of surface material, or a cliff, caused by gravity, but assisted by sub-aerial processes.
Sediment Cell
Areas of coast usually defined by headlands within which marine processes are largely confined with limited transfer of sediment from one cell to another.
Dynamic Equilibrium
The constantly changing nature of the relationship between erosion and deposition. The coastal system is designed so that (in theory) erosion is equal to the amount of deposition occurring.
Destructive Waves
Higher energy. Backwash is more powerful than swash, leading to removal of beach material. Break with great force over a short distance. Short wavelength. Higher wave height. Higher frequency 13-15 waves per minute.
Constructive Waves
Lower energy. Swash is more powerful than backwash, leading to deposition. Break gently over a longer distance. Long wavelength. Low in height. Low frequency 6-8 waves per minute.
Abrasion
The processes of scraping or wearing something away.
Corrosion
The process of materiel being dissolved/corroded by weak acids in the water.
Attrition
Material is eroded and made rounder by hitting against each other.
Hydraulic Action
Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.
Sub-aerial weathering
Physical, biological and chemical processes that work to break down rock material.
Freeze Thaw
Freeze thaw weathering involves water entering cracks in rocks and freezing. When the water freezes it expands, fracturing the rock.
Biological weathering
The action of tree roots spreading or rabbits burrowing through the soil in cliffs weakens the structure of the cliffs, leaving it vulnerable to be broken down by other processes.
Hydrolysis
A form of chemical weathering where elements/minerals react with water and weaken the structure of rock over time.
Solution
A form of chemical weathering where rock material is dissolved by weak acids in the water.
Carbonation
Similar to solution, but limestone is weathered by rainwater containing dissolved CO2 (carbonic acid).
Cliff
A vertical rock exposure. They are formed as erosional landforms due to the processes of erosion and sub-aerial weathering.
Wave Cut Platform
The flat area found at the base of a sea cliff that was created by the erosion of waves (wave cut notch and undercutting of overhanging cliff material). They are most obvious at low tide.
Cave
Formed when marine processes (such as hydraulic pressure) attack cracks or joints in the rock. These cracks become larger over time, and continual erosion creates this landform.
Arch
When continual erosion of a cave erodes through the cliff/headland, leaving rock material above.
Stack
When sub-aerial processes attack the overarching rock material over an arch. Once this material has been weakened it will collapse, leaving this landform.
Stump
When sub-aerial and marine processes attack the structure of a stack and erode it down to leave this landform.
Flandrian transgression
The period of warming and rising sea levels after the last glacial period (from 10,000 to 5,000 years ago).
Ria
An inlet of the sea formed by submergence of a river valley.
Fjord
A long, narrow, deep inlet of the sea between high cliffs formed by submergence of a glaciated U-shaped valley.
Estuary
A partly enclosed coastal body of water with one or more rivers flowing into it, which also connects to the sea.
Longshore Drift
Material is transported along the coast by the swash of waves up the beach and backwash out to sea. The direction of this process is influenced by the prevailing wind. Groynes are used to reduce the effect of this process.
Spit
An extended stretch of beach material that projects out to sea and is joined to the mainland at one end.
Tombolo
A spit that connects an island to the mainland.
Barrier Beach
where a beach or spit extends across a bay to join two headlands
Bay Head Beach
Areas of deposition that form due to refracted waves around headland and bays. Eroded material from headlands contributes towards creating this landform.
Cuspate Foreland
A triangular shaped landform created through longshore drift occurring in opposite directions.
Eustatic Sea level Rise
Global increase in sea levels due to melting of glaciers and ice caps.
Isostatic change
Localised changes in height of land due to post-glacial rebound or tectonic activity. This occurs at a faster rate compared to the increase in sea level.
Igneous Rocks
Rocks created through volcanic processes.
Sedimentary Rocks
Rocks created through deposition and sedimentation.
Metamorphic Rocks
Rocks created through the transformation of other rock types by heat and pressure.
Discordant Coastline
Rocks layered at right angles to the shoreline. This gives rise to differential rates of erosion and the formation of headlands and bays.
Concordant Coastline
Rocks layered parallel to the shoreline.
Bay
an area of weaker rock that has been eroded between headlands of more-resistant rock. When waves enter a bay,their energy is dissipated leading to deposition and the formation of a beach
Cliff Profile
the shape and characteristics of a cliff, often viewed as a cross-section
Constructive Wave
a low, surging wave with a strong swash that surges up a beach usually forming a berm
Drift-aligned
where sediment is transferred along the coast by longshore drift
Anticline
a ridge or fold of stratified rock in which the strata slope downwards from the crest.
Syncline
a trough or fold of stratified rock in which the strata slope upwards from the axis.
Raised Beach
the result of isostatic recovery which raises wave-cut platforms and their beaches above the present sea level
Slumping
when clay slides downslope under gravity as a result of rains entering the cracked clay causing it to become lubricated and much heavier
Relict Cliff
the result of isostatic recovery which raises cliffs and the backshore above the present sea level
Double spit
Formed from a breach of a pre-existing spit or bar, usually by a river or storm
Recurved spit
As spits build out into deep water they require increasing volumes of sediment to build above the high mark. The tip or distal turns towards the land where it’s shallower. If it built out in deep water it would be eroded.
Mechanical Weathering
The physical breaking down of rock in to smaller pieces (by water, air, temperature, wind).
Chemical Weathering
The erosion/disintegration of rocks through chemical reactions.
Blockfall
Also known as rockfalls, are a rapid form of mass movement. Blocks of rock can be dislodged by mechanical wearing or hydraulic action. Undercutting of cliffs to create wave cut notches can lead to large blockfalls.
Rotational slumping
Occurs along a curved failure surface
Landslide
Rocks that are jointed, or have bedding planes parallel to the slope/cliff are susceptible. High levels of water reduces friction, causing rock to slide (along a slide/slip plane).
Sediment cell
The movement of sediment along the coast and between the beach, cliffs and sea through the process of erosion, transportation and deposition. Action taken in one place can disrupt the flow of sediment to another. Each cell is defined by physical barriers (e.g. headland). They are also categorised as systems - possessing sources, transfers and sinks (stores) of sediment.
