Coastal Landscapes
3a. Emergent coastal landscape form as sea level falls
Eustatic change: Global change in volume of sea water resulting from rise/fall in level of sea itself e.g.
caused by retreat of ice following glacial period. Influenced by variations in mean global temp.
Isostatic change: Local change in sea level resulting from land rising/falling relative to sea e.g. tectonic
movements.
Cooling climate and emergent landscapes:
Climate change and sea level fall:
- Fall in global temp → more precipitation in form of snow → snow turns to ice → more water
stored on land as solid ice rather than liquid water which is returned to ocean
Influence of sea level fall on geomorphic processes and landforms:
- Landforms shaped by wave processes when sea level was higher exposed when sea level falls –
may be found inland from present coastlines
Raised beaches, marine terraces and abandoned cliffs:
- Raised beaches: Areas of former shore platforms left at higher level than present sea level. Often
found distance inland from present coastline.
- Beaches and cliff lines elevated above sea level and exposed following deglaciation and unloading
of ice sheets from N Britain.
- Marine terraces formed where expanse of gently sloping, formerly submerged land has been
exposed by uplift/lowering of sea levels. Much larger scale landscape features than raised
beaches
- e.g. on Southern tip of Isle of Portland nr Weymouth, Dorset, raised beach present, height of 15m
above present day sea level. Thought to have formed around 125,000 yrs. ago during Tyrrhenian
inter-glacial period - sea levels much higher. Portland limestone eroded by hydraulic action –
exploitation of bedding plane weaknesses.
Modification by present and future climates and sea level change:
- As now exposed and above waterline, emergent landforms now affected by weathering + mass
movement processes e.g. freeze-thaw.
- In post-glacial periods when climate is wetter and warmer = vegetation forms.
- Warming is predicted in future = chemical and biological weathering more influential
- If rise in temps is enough for sea level to rise, emergent features may become closer to coastline
and wave processes will be an influential factor
3a. Emergent coastal landscape form as sea level falls
Eustatic change: Global change in volume of sea water resulting from rise/fall in level of sea itself e.g.
caused by retreat of ice following glacial period. Influenced by variations in mean global temp.
Isostatic change: Local change in sea level resulting from land rising/falling relative to sea e.g. tectonic
movements.
Cooling climate and emergent landscapes:
Climate change and sea level fall:
- Fall in global temp → more precipitation in form of snow → snow turns to ice → more water
stored on land as solid ice rather than liquid water which is returned to ocean
Influence of sea level fall on geomorphic processes and landforms:
- Landforms shaped by wave processes when sea level was higher exposed when sea level falls –
may be found inland from present coastlines
Raised beaches, marine terraces and abandoned cliffs:
- Raised beaches: Areas of former shore platforms left at higher level than present sea level. Often
found distance inland from present coastline.
- Beaches and cliff lines elevated above sea level and exposed following deglaciation and unloading
of ice sheets from N Britain.
- Marine terraces formed where expanse of gently sloping, formerly submerged land has been
exposed by uplift/lowering of sea levels. Much larger scale landscape features than raised
beaches
- e.g. on Southern tip of Isle of Portland nr Weymouth, Dorset, raised beach present, height of 15m
above present day sea level. Thought to have formed around 125,000 yrs. ago during Tyrrhenian
inter-glacial period - sea levels much higher. Portland limestone eroded by hydraulic action –
exploitation of bedding plane weaknesses.
Modification by present and future climates and sea level change:
- As now exposed and above waterline, emergent landforms now affected by weathering + mass
movement processes e.g. freeze-thaw.
- In post-glacial periods when climate is wetter and warmer = vegetation forms.
- Warming is predicted in future = chemical and biological weathering more influential
- If rise in temps is enough for sea level to rise, emergent features may become closer to coastline
and wave processes will be an influential factor
