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Geography - Coastal Landforms - Coggle Diagram
Geography - Coastal Landforms
Coastlines
Concordant
alternating bands of hard and soft rock parallel to coast
Discordant
alternating bands of hard a soft rock perpendicular to coast
Geological Structure
Hard rocks
granite
long time to erode
Soft rock
clay
erode quicker
Erosional Landforms
Headlands and Bays
Discordant
weaker rock eroded faster
bay with gentle slope
resistant rock erodes slower
forms headlands with steep sides
Bays are sheltered
deposition takes place
beaches
Caves, Arches, Stacks and Stumps
Caves
Headland rocks have cracks (faults)
waves widen cracks
repeated erosion
cave
hydraulic power and abrasion
weaknesses
Arch
continued erosion deepens cave
breaks through headland
arch
Stack
arch collapses
stack
weathering
gravity
too heavy
Stump
continued erosion
stump
Wave-cut Platforms
Destructive waves erode foot of cliff
hydraulic action and abrasion
up to high-tide mark
Formation of a
wave-cut notch
erosion undercuts cliff
Cliff collapse
notch deepens
cliff becomes unstable and collapses
gravity and weathering
Cliff retreat
collapsed material is washed away
cliff line to retreat inland
Wave-cut platform
repeated cycles
gently sloping rocky surface at base of cliff
Depositional Landforms
Beaches
deposits of sand and shingle
sandy beaches
sheltered bays
low-energy waves
long, gentle slope
shingle beaches
wash away finer sands
leave larger pebbles
high-energy waves
steep slope
Swanage Bay
Spits
significant longshore drift
coastline bend sharply
sediment is deposited out to sea
forms extension from land
spit grows further out to sea
strong winds and waves
recurved end
sheltered water behind spit
2 more items...
Dawlish Warren, Devon
Bars
spit joins two headlands
bay cut off from sea
lagoon behind bar
Slapton Sands, Devon
Offshore Bars
form out to sea
gently sloping coast
waves deposit sediment offshore
friction with seabed
not connected to coast
Hordle Sand Bar, Hampshire
Sand Dunes
sand moved up beach by wind
obstacles decrease wind speed
sand deposited
Embryo Dunes
colonised by plants
roots stabilise sand
Foredunes
rotting vegetation adds organic matter
fertile
Mature dunes
Dune slacks
wind forms depressions in sand
ponds
Dawlish Warren