coasts revision cards Flashcards
what are the three stages in a sediment cycle?
Inputs (where sediment comes from)
transfers (the processes)
outputs eg spits and beaches
name the four parts of the littoral zone in order
backshore
foreshore
nearshore
offshore
what are the short term factors effecting the Littoral zone?
tides and storm surges
what are the long term factors affecting the Littoral zone?
changes in sea level
climate change
what are the three tides
low
high
spring tides
what is abrasion
sediment moving along the shoreline causing it to be worn down over time
what is attrition?
wave action causes rocks and pebbles to hit against each other, causing rocks to be smaller and more round. Attrition does not cause coastal erosion
what is hydraulic action?
A wave crashing into a rock or cliff face forcing air into the cracks, the high air pressure causes the cracks to force apart and widen
when are erosion rates highest?
when waves are high and have a long fetch.
waves are perpendicular to the cliff.
heavy rainfall occurs.
Winter waves are more destructive.
rate of erosion by rock type
sedimentary highest
metamorphic second
igneous slowest
describe longshore drift.
waves hit at an angle determined by the direction of the prevailing wind. The waves push sediment in the direction of the wind in the swash. Due to gravity, the wave then carries sediment back down the beach in the backwash. This moves sediment along the beach over time.
what is traction?
large, heavy sediment rolls along the sea bed, being pushed by currents.
what is saltation?
smaller sediment bounces along the sea bed, being pushed by currents
what is suspension?
small sediment is carried within the water column (a body of water)
what is solution?
Dissolved material is carried within the water
what is a swash aligned beach?
waves break with no angle so no LSD
what is drift aligned?
waves break at an angle so there is LSD
what is deposition?
deposition occurs when a wave loses energy meaning the sediment becomes too heavy to carry, deposition is gradual.
what is gravity settling?
the waves energy becomes very low and so heavy rocks and boulders are deposited followed by the next heaviest sediment
what is Flocculation?
clay particles clamp together due to chemical attraction and then sink due to their high density
name 6 depositional landforms
Tombolo cuspate forelands offshore bars spits bars sand dunes
name the processes of transportation
traction
saltation
suspension
solution
name two depositional processes
Flocculation
gravity settling
how is a tombolo formed?
formed due to wave refraction off the coastal islands reducing wave velocity
how are cuspate forelands formed?
only occurs with triangular shaped headlands. Longshore drift along each side of the headland will create beaches, which where they meet, will form a cuspate foreland
how are offshore bars formed?
They can be formed as the wave breaks early, scouring the sea bed and instantly depositing its sediment as a loose-sediment offshore bar
how are sand dunes formed?
sand dunes occur when prevailing winds blow sediment to the back of the beach and therefore the formation of dunes requires large quantities of sand and a large tidal range
name the steps of how sand dunes are formed in order?
embryo dunes yellow dunes grey dunes dune slack heath and woodland
what happens at the embryo phase?
sand starts to accumulate around a small obstacle
what happens at the yellow dune phase?
more sand accumulates. vegetation may develop which stabilises the dune
what happens at the grey dune phase?
sand develops into soil with lots of moisture and nutrients, as vegetation dies, enabling more varied plant growth
what happens at the dune slack phase?
the water table rises closer to the surface, or water is trapped between hollows between dunes during storms, allowing the development of moisture- loving plants
what happens at the heath and woodland phase?
greater nutrients develop allowing less brackish plants to thrive. Trees grow and act as a natural windbreak
name 3 weathering processes
freeze thaw
salt Crystallisation
wetting and drying
what is freeze thaw?
water enters the cracks in the rocks and when it freezes it expands which increases the pressure acting on the rock causing it to eventually break
what is salt Crystallisation?
as sea water evaporates, salt is left behind. Salt crystals expand overtime causing more pressure on the rocks, which forces cracks to widen
what is wetting and drying?
some rocks expand when wet and contract when dry. This causes rocks to break
examples of chemical weathering?
carbonation
oxidation
solution
examples of biological weathering
plant roots
birds
rock boring
what does the type of mass movement depend on?
The angle of the slope/cliff
The rocks lithology/geology
The vegetation cover on the cliff face
The saturation of the ground/previous weather patterns
What is soil creep?
The slowest but continuous form of mass movement involving the movement of soil particles downhill
What is rock fall?
Rocks falling
What is slumping?
Occur when soil is saturated with water, causing a rotation movement of soft materials (such as clay and sand) forming rotational scars and terraced cliff profiles
What is rock slide?
Water between joints and bedding planes (which are parallel to the surface) can reduce friction and lead to more sliding
What is a concordant coast?
Rock strata runs parallel to the coast. Concordant coasts can lead to the formation of the Dalmatian coas.
How are Dalmatian coasts formed?
Formed where the geology creates valleys parallel to the coast so that when sea levels rise, a series of elongated islands remain offshore
What is a discordant coast?
This is when the rock strata runs perpendicular to the sea