1.3. How do coastal landforms evolve over time as climate changes?
3a. Emergent coastal landscapes form as sea level falls - How landforms in emergent landscapes are influenced by
falling sea levels due to a cooling climate
- Raised beaches (Southern Coast of Isle of Portland)
Sea level change: Modification during previous glacial periods:
Raised beaches emerge when there’s a eustatic sea Fluctuations + & - 0 degrees celcius - high rates of freeze thaw during last peri-
level fall glacial period (in between glacial & inter-glacial) on cliff face, resulting in high
Beaches form when sea level used to be much rates of mass movement from the cliff face (Isle of Purbeck)
higher Mostly sub-aerial processes some marine
E.g. raised beach at Portland formed when sea level Repeated freeze thaw weathering results in mixing of the horizontal bedding
was 15m higher than current sea level planes of sandstone at Portland beneath the beach (cryoturbation)
Land has risen from the sea in the past as a result of Marine deposition to create the beach
isostatic processes (earthquake energy) Original landform feature: If drift aligned beach, LSD would have occurred
A marine landform –
Climate: Modification by present/future geomorphic processes:
beach (depositional) /
Formed during warmer interglacial period 125,000 shore platform (erosional) No longer affected by coastal erosion processes - exist outside the marine zone
years ago then emerged during cooler climate created within the tidal Still affected by sub-aerial processes & often weathered biologically, chemically
Since that time as temps have decreased: range of the height of the & via freeze-thaw weathering (fluctuations above & below 0, repetition, in situ)
HWM & LWM Warmer & wetter conditions encourage vegetation to grow – increasing rate of
- Snow falls
Now left at a higher level biological weathering
- Builds up for 1000’s of years
than the present sea level Future warming may induce more chemical weathering, especially carbonation
- Compression of snow turns layers into ice on limestone cliffs
(diagenesis) Future sea level rise of 15m may result in these landforms becoming closer to
- THEREFORE: transfer of water from ocean to the marine zone where they may be subjected to marine processes once again
land – reduction of amount of water in ocean
- Cooling contraction – each water molecule
occupies a smaller volume
3a. Emergent coastal landscapes form as sea level falls - How landforms in emergent landscapes are influenced by
falling sea levels due to a cooling climate
- Raised beaches (Southern Coast of Isle of Portland)
Sea level change: Modification during previous glacial periods:
Raised beaches emerge when there’s a eustatic sea Fluctuations + & - 0 degrees celcius - high rates of freeze thaw during last peri-
level fall glacial period (in between glacial & inter-glacial) on cliff face, resulting in high
Beaches form when sea level used to be much rates of mass movement from the cliff face (Isle of Purbeck)
higher Mostly sub-aerial processes some marine
E.g. raised beach at Portland formed when sea level Repeated freeze thaw weathering results in mixing of the horizontal bedding
was 15m higher than current sea level planes of sandstone at Portland beneath the beach (cryoturbation)
Land has risen from the sea in the past as a result of Marine deposition to create the beach
isostatic processes (earthquake energy) Original landform feature: If drift aligned beach, LSD would have occurred
A marine landform –
Climate: Modification by present/future geomorphic processes:
beach (depositional) /
Formed during warmer interglacial period 125,000 shore platform (erosional) No longer affected by coastal erosion processes - exist outside the marine zone
years ago then emerged during cooler climate created within the tidal Still affected by sub-aerial processes & often weathered biologically, chemically
Since that time as temps have decreased: range of the height of the & via freeze-thaw weathering (fluctuations above & below 0, repetition, in situ)
HWM & LWM Warmer & wetter conditions encourage vegetation to grow – increasing rate of
- Snow falls
Now left at a higher level biological weathering
- Builds up for 1000’s of years
than the present sea level Future warming may induce more chemical weathering, especially carbonation
- Compression of snow turns layers into ice on limestone cliffs
(diagenesis) Future sea level rise of 15m may result in these landforms becoming closer to
- THEREFORE: transfer of water from ocean to the marine zone where they may be subjected to marine processes once again
land – reduction of amount of water in ocean
- Cooling contraction – each water molecule
occupies a smaller volume
