Unit 1- Coastline Flashcards
How is a wave formed?
-Circular orbit
- Friction from rising seabed cuases eliptical orbit
- Top of wave breaks over
What is a constructive wave?
-Less energy
-Larger swash —-> deposits material
-Low frequency ( >10 per min)
-Large wavelength + short
Where are constructive waves found?
-Bays
-Lower depth
-More friction from ocean floor
What is a destructive wave?
-High energy
-Larger backwash —->erodes
-High frequency (10-14 per min)
-Tall but short wavelength
How are destructive waves formed?
- Long fetches (distance)
- Storms
- Deep sea (headlands)
x3
Weathering?
- Mechanical
- Chemcial
- Biological
What is mechanicle weathering + example?
-Physical erosion (by biotic things)
-Freeze-thaw:
Day temp warmer, water gets in rock crack
Night temp colder, water freezes + expands
—–> crack increased + repeat on larger scale
What is chemical weathering + example?
- Erosion by chemical changes
-Carbonation:
Acid rain erodes limestone
What is biological weathering + example?
- Living organsims erode
-Plants grow and expand in cracks of rock
What is longshore drift?
- Prevailing wind at an angle to coast
- Waves income at an engle
- Waves deposite material and remove material at that incoming angle
- Backwash is 90 degrees
-Cuases sediment movement in a zig zag motion
Cuases mass movement of sedimentation
What are the two types of coastline?
-Concordant
-Disconcordant
What is concordant coastline?
- Layers of hard and soft rock parallel to coast
-coast against one type of rock
What is disconcordant coastline?
- Layers of hard and soft rock perpendicular to coast
-coast against two types of rock
How is a bay and headlands formed?
- Normally disconcordant coastline
- water erodes soft rock, whilst hard rock on either side remain large
Famouse bay on a concordant coastline?
where is it
Lulwoth cove
dorset
How was lulworth cove formed?
-Water eroded narrow part of hard rock
- Quickly eroded soft rocks behind it
- Cuased almost circular bay
How are caves formed?
Hydraulic action and abrasion eroded a dent in rock
How are arches formed?
Cave in headland eroded all the way through
How are stacks formed?
- Arch rock collapses without support
How are stumps formed?
- Stack rock weathered down
Famouse arch?
where
-Durdle door
-Dorset
How is a wavecutt platoform formed?
- Water erodes rock at sea level
- Rock above collapses
- Land retreats
bedding planes how soft and hard rock layered in cliff
What is a beach
Buffer between land and sea
How is a spit formed?
-Narrow land of sand and shingle
-Deposited material behind headland (estuary)
-Secondary wind cuases light curve
-Longshore drift continues as coastline changes direction
-Shallow cuases lots of deposition
