A-Level Geography - Physical - Sea Level Change
- Created by: Noah_S
- Created on: 29-10-21 15:43
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- Sea Level Change
- Causes
- Isostatic
- Local land can move vertically in relation to the sea, raising/lowing relative sea levels
- Land may be pushed down by additional weight from ice or sediment, and when removed isostatic rebound occurs
- Glacio-isostatic subsidence is where the crust is depressed by ice sheets, like in Scotland
- Sediment-isostatic subsidence is when sediments accumulate in a large delta, like the Mississippi, depressing the crust
- Eustatic
- Fluctuations in the Earth's atmospheric temperature can change the volume of water in the oceans
- Glaciers & ice sheets melt and retreat, increasing the volume of the oceans
- Seawater also expands thermally, rising 0.8m for every 1*C rise in temperature
- Tectonic
- Techno-Eustatic is if the shape of the ocean basins is altered, their holding capacity will change
- If capacity is reduced, sea level rise will occur
- Orogenic movement (mountain building) episodes causes the uplift of the land, resulting in a lowing of relative sea level
- Occurs at converging plate margins
- Creation of volcanic ocean islands displaces water and increases sea levels
- Techno-Eustatic is if the shape of the ocean basins is altered, their holding capacity will change
- Isostatic
- Emergent Landforms
- Raised Beaches
- Formed when the fall in sea level leaves beaches above the high tide mark
- Over time, beach sediment becomes vegetated and develops into soil
- Relict Cliffs
- Cliffs above raised beaches are no longer eroded, so they get covered by vegetation
- Not uncommon to see wave-cut notches, caves, arches and stacks within relict cliffs
- Degrades over time
- Information
- Formed when the relative sea level drops, raising existing coastal landforms upwards
- Examples can be found in Scotland, as it is being raised due to isostatic rebound
- Raised Beaches
- Submergent Landforms
- Rias
- Formed where river valleys are partially submerged
- Have a gentle long and cross-profile, deepest at their mouth and becomes narrower and shallower inland
- Example is Milford Haven in South Wales
- Fjords
- Formed from submerged glacial valleys
- Are straight and narrow, with steep sides. They have a shallow mouth, called the threshold, formed by deposition of glacial sediment
- Can be very deep, like in Sognefjorden in Norway, which is over 1000m deep in places
- Dalmatian Coastlines
- Formed when parallel valleys to the coastline are flooded
- Have islands parallel to the coastline
- An example is the Dalmatian Coast in Croatia, which the landform is named after
- Rias
- Causes
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