Isostatic And Eustuatic Changes Flashcards
What is a Eustatic change?
A global change in sea level resulting from a fall or rise in the level of the sea itself
What is a isostatic change?
Local changes in sea level resulting from the land rising and falling, relative to the sea
What are the two major factors when it comes to Eustatic change?
Thermal expansion (where the volume of water increases as it gets warmer)
Ice melt (melting of glaciers and ice sheets)
Thermal expansion is responsible for 70% of sea level rise
What is the trend of rising sea level in the uk (isostatic change)?
The north is rising (around 0.5 mm per year)
Fastest rate of rising is in the west of Scotland (at 1.5 mm per year)
The south of uk is sinking, fastest rate of decline is in the south west (over 1 mm of decline per year)
How is the sea levels measures?
Using GPS trackers
What is the final factor influencing rising and falling of sea levels?
Tectonics - land rising or sinking, when tectonic plates move, they can cause land to rise or sink. If land rises from the sea, water levels drop, wherever if land sinks, sea levels can seem to rise
How do isostatic processes show the coastal system as being open?
As they are linked to the rock system in the coastal system. This is because the structure of the earth allows for the sinking of the land and then the rebounding of the land. Also links to the carbon cycle, as the amount of carbon in the air determines how hot or cold the atmosphere is. We know that carbon is linked with climate change, leading to global warming
How do eustatic processes show the coastal system as being open?
They are linked to the atmospheric system because the temperature of the air determines these changes in the sea levels
What does submergence mean?
When something submerges it sinks or goes below (like a submarine below the sea)
Wha does emergence mean?
When something emerges, it appears or rises up
How are isostatic and eustatic changes involved with the submergence of coastlines?
1) eustatic sea level rise
2) isostatic fall
How are isostatic and eustatic changes involved in the emergence of coastlines?
Isostatic rise
Eustatic fall
How are raised beaches formed?
They form when sea levels rise or fall. During glaciation, sea levels drop, and when ice melts they rise again, causing erosion and sediment deposition along coastlines. If the land is uplifted by tectonic activity, these beaches can become elevated above current sea levels.
Give an example of raised beaches:
Isle of Skye, Scotland
Describe the formation of Rias:
Are formed when rising sea levels flood narrow winding inlets and river valleys. They are deeper at the mouth of the inlet, with the water depth decreasing further inland. This process typically occurs in areas with a softer bedrock, allowing for greater erosion and the development of these characteristic features. They often have a dendritic shape
What is an example of a Ria?
River dart, Dartmouth
Describe the formation of Fjords:
Formed when rising sea levels flood deep glacial valleys to create natural inlets and harbours. They are deeper in the middle section than they are in the mouth, with the shallower section identifying where the glacier left the valley
What is an example of a fjord?
Sognefjord - Norway
How are marine platforms/terraces formed?
A platform is eroded as waves erode a notch at the base of the sea cliff, which causes overhanging rock to fall. As the sea cliffs are attacked, weak rocks are quickly eroded, leaving stronger rocks. With sea level change, platforms may emerge or submerge. Wave cut platforms that have emerged are the marine platforms
What is an example of a marine platform?
Kimmeridge bay, Dorset
Describe the formation of fossil cliffs:
- they are found at the back of raised beaches, a steep slope displaying evidence that they were formed through marine erosion but are now above high tide level. - formed when the land rebounds after an ice age
- isostatic rise
- emergent landforms
What is an example of fossil cliffs?
Infife, Scotland
Describe the formation of Dalmatian coasts:
- a concordant coastline produced by the geological structure of folds parallel to the coast
- formed by tectonic forces and rising sea levels
- eustatic sea level rise
- submergent
- water floods the valleys and leeves behind islands
What is an example of a Dalmatian coastline?
Dalmatian coast, Croatia
