Coasts Flashcards
(41 cards)
mass movement
the movement of material down a slope due to gravity
sliding
large volumes of material moves downhill very rapidly, in a straight line, along a joint in the rock
slumping
saturated soil or rock, collapses in a rotational movement, down a curved slope
factors that affect mass movement
Slope angle
Vegetation cover
Water content
Rock type
Human activity
Climate
types of erosion
abrasion
hydraulic action
attrition
solution
hydraulic action
the sheer power of the waves as they smash against the cliff. air becomes trapped in the cracks in the rock and causes the rock to break apart from the pressure.
attrition
rocks in the water knock against each other. they break apart to become smaller and rounder
abrasion
pebbles grind along a rock platform, like sandpaper. over time, the rock becomes smooth
solution (erosion)
sea water dissolves certain types of rocks and breaks down some rock. in the UK, chalk and limestone cliffs are prone to this.
how are headlands and bays formed on a discordant coastline?
On a discordant coastline, Alternating bands of hard and soft rocks run perpendicular to oncoming waves The soft rock (e.g. clay) is eroded backward, forming an inlet As the inlet continues to erode it curves inward, and a bay is formed, usually with a beach The hard rock (e.g. limestone) is left protruding out to sea as a headland.
concordant coastline
coastline with bands of more and less resistant rocks that run parallel to the coastline e.g. Lulworth Cove
discordant coastline
coastline with bands of more and less resistant rock running perpendicular to the coastline. headlands and bays form here e.g. Swanage Bays
features formed on a discordant coastline
alternating bands of hard and soft rock form headlands and bays
how do concordant coastlines affect coastal landforms
how do discordant coastlines affect coastal landforms
deposition
a physical process where rocks and material are dropped by the waves that carry them
how does deposition work
when the sea loses energy, the waves drop the material it has been carrying. it can occur on coastlines that have
constructive waves
factors leading to deposition
waves starting to slow down and lose energy
shallow water
sheltered areas, eg bays
little or no wind
spit
a ridge of sand or shingle deposited by the sea. it’s attached to the land at one end, the other extended into the sea
bar
a ridge of sand or shingle deposited by the sea, across the entrance of a bay or river mouth
tombolo
a spit connecting an island to the mainland
bay
an area of sea, curved in shape which has been eroded between two headlands
saltmarsh
coastal wetlands that are flooded and drained by salt water brought in by the tides
headland
a steep sided cliff area of more resistant rock jutting out into the sea