Coastal Landscapes and Change Flashcards
Define Coast
Where the land means the sea
Define dynamic
Changing
Define Littoral zone
The wider coastal zone including adjacent land areas and shallow parts of the sea just offshore
Define estuary
Where a river widens as it meets the sea
Define Rocky (Cliffed) coastline
It has cliffs varying in height from a few metres to hundreds.
How are rocky coastlines formed?
Varied resistant rock
Define coastal plains
The land gradually slopes towards the sea across an area of deposits sediment
What are the most common coastal plains?
Sand dunes and mudflats
What is another name for coastal plain?
Alluvial coast
Define Cliff
A steep rock face, especially at the edge of the sea
Define beach
A pebbly or sandy shore, especially by the sea between high and low marks
Define backshore
A zone of the shore or beach above the high water line, acted upon only by severe storms or exceptionally high tides
Define foreshore
The ground between the water’s edge and broken up land; land along the edge of the body of water
Define nearshore
The region of the sea or seabed relatively close to the shore
Define offshore
Situated at sea some distance from the shore
Name 3 characteristics of cliffs
Made up of variations in rock
Formed from rock
Varying in height
What is the backshore affected by?
Waves during high tides and major storms
What is another name for major storms?
Spring tides
What are 2 characteristics of the nearshore?
Sediment is transferred
Intense human activity e.g. fishing
How can coastal plains be formed
Falling sea level
Deposition of sediment by rivers
Define delta
Where a river splits into many channels as it meets the sea
Define accretion
The deposition of sediment at the coast and the seaward growth of the coastline, creating new land. It often involves sediment deposition being stabilised by vegetation
Define dynamic equilibrium
The balanced stated of a system where inputs equal outputs over time
Define cliff profile
The height and angle of a cliff face as well as its features
Name 3 characteristics of Marine cliff profile
Marine erosion by wave action dominates
Cliffs are steep and un-vegetated
Little rock debris at the base of the cliff as it is quickly transported away by the waves
Name 3 characteristics of sub aerial cliff profile
Shallower curved profiles and lower relief
Slowly moves rock sediment down slope
Limited amount of marine wave erosion means its not removed
Define morphology
The shape of the land
Define geology
Rock type
Define strata
Different layers of rock
Define discordant coastline
Rock strata intersect the coast at right angles so geology varies along the coast
Define concordant coastline
Rock strata run parallel to the coastline. Also known as pacific coasts
Define bedding planes
Natural breaks in the rock strata caused by gap in time during periods of rock formation
Define joints
Vertical cracks
Define folds in rock
Formed by pressure during tectonic activity which makes rock buckle and crumble
Define fault
Formed where the stress or pressure to which a rock is subjected exceeds it’s internal strength. It fractures and slips along a fault plane
Define dip in rock
The angle at which the rock strata lie
Define Anticline
A upward fold in the rock strata
Define syncline
A downward fold in the rock strata
What are 5 factors leading to erosion
Vertical joints- opened by weathering Vertical bedding planes High wave energy Less resistance rock Seaward dip
Define differential erosion
Being eroded at different rates
Define recession rate
How fast a coastline is moving inland
What do recessive rates depend on?
Lithology
Angle of dip (bedding planes- angles)
Weathering
Wave energy
Define composite cliffs
If a cliff is made of different rock layers
Define permeable rocks
Allows water to flow through them
Define impermeable rock
Don’t allow groundwater to flow through them
Define weathering
The breakdown of rock in situ by physical and chemical processes due to the presence of water, plants and animals. Rates vary due to temperature, rock type and time.
Define mass movement
The downslope movement from rock, earth or water
Define Halosere (salt marsh)
Change in a habitat in a saline environment
Define climax community
The stage in community succession where the community has become relatively stable through successful adjustment to its environment.
Define Pore water pressure
The pressure water experiences at a particular point below the water table due to the weight of water above it
Define alluvial coast
Coast made of a variety of materials, including fine particles of sand, silt and clay
Define surface run off
Water from rain,snowmelt etc that flows over the land
Define fissure
A long, narrow crack
Define Haff coast
A shallow fresh-water coastal lagoon formed by the growth of a sand spit
Define Psammosere (sand dunes)
A seral community (stage before climax community), an ecological succession that begun life on newly exposed coastal sand.
How do sand dunes stabilise sandy coastlines?
Plant roots bind the sediment together and stabilise the area. Vegetation causes friction at the ground surface, reducing wind speed and allowing more sand to be deposited
Define plant succession
The changing structure of a plant community over time as an area of initially bare sediment is colonised by plants
Define plant species
The first plants to colonise an area of bare sediment
What does wave size depend on?
The strength of the wind
The duration the wind has blown over open water for
Water depth
Fetch
Define Fetch
The uninterrupted distance across water over which a wind blows, and therefore the distance the waves have to grow in size.
Define Swash
The flow of water up a beach as a wave breaks
Define Backwash
When water runs back down the beach to meet the next incoming wave
Define Beach morphology
The shape of a beach, including its width and slope (the beach profile) and features such as berms, ridges and runnels. It also includes the type of sediment (shingle, sand, mud) found at different locations on the beach.1
Name the 4 types of erosion
Hydraulic action, attrition, abrasion, solution
How does lithology in terms of abrasion influence erosion?
When the waves advance, they pick up sand and pebbles from the seabed. Then, when they break at the base of the cliff, the transported material is hurdled at the cliff foot.
What determines how much erosion is present?
The size and amount of sediment picked up
How does lithology in terms of hydraulic action influence erosion?
When the waves advance, air can be trapped and compressed (either in joints or between the breaking wave and cliff). This continuous process can weaken joints and cracks in the cliff- causing rock to break off.
What influences the amount of hydraulic action?
The force of the waves
How does lithology in terms of solution influence erosion?
When cliffs are formed from alkali rock (e.g. chalk), or an alkali cement bonds the rocks together, solution by weak acids in seawater can dissolve them.
How does lithology in terms of attrition influence erosion?
Gradual wearing away of rock particles by impact and abrasion, as the pieces of rock are moved by waves, tides and currents. This gradually reduces the particles size and makes stones rounder and smoother.
Name different types of erosional landforms
Wave cut notch, wave cut platforms, cave, arch, stacks, stumps, cliffs.
Name 4 types of transportation
Traction, saltation, suspension, solution
What does transportation depend on?
Wave energy
Describe the steps of longshore drift
Most waves approach a beach at an angle- generally from the same direction at the prevailing wind. Material is carried up the beach at an angle. The backwash then pulls material down at 90°.
What is lateral shift?
The effect of movement of sediment up and down the beach.
What creates significant and sustained longshore drift?
Strong prevailing winds and large waves
Define currents
Flows of sea water in a particular direction driven by winds or differences in water density, salinity or temperature. They may have continual global currents or more localised sporadic rip tides
Define tidal range
The difference between the high and low tides
What does high tidal ranges create?
Relatively high tidal currents
What are the 8 different coastal depositional landforms?
Spits, recurved spits, beach, Offshore bars, barrier beaches, barrier island, tombolo, cuspate foreland
Define spit
A long, narrow feature made of sand and shingle, which extends from the land into the sea (or part of the way across an estuary)
What can spits form?
Drift aligned beaches
Define recurved spit
When the end of the spit will begin to curve round, as wave refraction carries material round into the more sheltered water behind the spit
