coastal landforms Flashcards
headlands and bays
they form on a discordant coastline.
destructive waves erode the coast through abrasion
differential erosion occurs, so soft rock erodes faster creating bays
hard rock erodes slower and remains jutting out, creating headlands
wave cut platforms
destructive waves erode the cliff through abrasion
over time, this erosion creates a wave cut notch
this notch gradually gets larger and the cliff above it is unsupported
mass movement occurs as a result of gravity and the cliff retreats
wave cut platform is uneroded section of the original cliff at the base
process starts to repeat with new notch forming
caves, arches and stacks
destructive waves erode the headland through processes such as abrasion
faults and joints in the resistant rock are more vulnerable to erosion. Hydraulic action and abrasion will widen these
eventually abrasion and hydraulic enlarge the cracks into a cave
waves continue to abrade the cave, making it deeper
caves on both sides of the headland will eventually erode though the headland creating an arch
this arch is enlarged by waves at the base and weathering at the top
at the top of the arch is unsupported, and it suffers from weathering, eventually it will collapse due to gravity
this leaves an isolated pillar of rock called a stack
beach formation
a beach can form on a low lying coast is loose material such as gravel or sand is available
this could be carried onto the shoreline by the swash of waves
as waves slow down their energy drops and this material is deposited
the backwash of waves can extend the beach by longshore drift
spit formation
prevailing wind pushes waves at an angle towards shore
these waves pick up sediments and swash pushes it up the beach at an angle
when the waves retreat down the beach at a right angle, it drags sediment back with it as backwash
longshore drift moves sediment across the beach
where a river enters the sea, it slows down the waves and causes deposition of sediment to occur
deposited sediment builds up to form a spit, with a curved end because of waves pushing sediment inland
bar formation
a bar is a ridge of sand or shingle across the entrance to a bay or river mouth
the formation of a bar begins in the same way as a spit
material is transported along the coast by longshore drift and deposited where there is a bend in the coastline
deposition then continues in a line across the entrance to the bay or river mouth, trapping fresh water behind
