Sea Level Change

Question 1

How much lower was the sea level 18,000 years ago?

Answer 1

110meters

Question 2

Which time period has since the greatest amount of sea level change?

Answer 2

Last 500 years risen by 10 meters

Question 3

What is eustatic change? What are its causes?

Answer 3

Ocean level rises reative to the land

1) thermal expansion
2) melting of ice sheets
3) tectonic activity - displacement of water by moving the ocean basin up

Question 4

What is isostatic change?

Answer 4

Level of land changes relative to the sea

1) tectonic activity - fold mountains
2) glaciation - heavy glaciers push the ground into the upper layer of the mantle, upon melting the land rebounds out of the asthenosphere
3) subsidence - ground water abstraction causes collapses

Question 5

Where do coastlines of emergence occur?

Give some features

Answer 5

Where sea level has lowered,
Raised beaches along with relict landforms
Wave cut platforms

Question 6

What are coastlines of submergence ?

What landforms occur?

Answer 6

Coastlines that have seen severe sea level rises
Rias - flooded river valleys with gentle profiles
Fjords - flooded glacial valleys with steep sides
Dalmatian coasts - concordant geology has valleys parallel to the coast which are flooded

Question 7

How fast are sea levels rising currently?

Answer 7

2mm per year

Question 8

Give four impacts that sea level rise has on coasts.

Answer 8

Increased storm frequency due to altered wind patterns etc
More costal flooding = lost agricultural land 0.3 meter rise = 8000Km2 in Bangladesh
Contamination of fresh water sources reduces biodiversity
Faster costal erosion rates