Topic 3(4)-Sea Level Changes

Question 1

What are the two types of sea level changes

Answer 1

Eustatic, Isostatic

Question 2

Eustatic sea level change definition

Answer 2

Caused by a change in the VOLUME OF WATER in the sea, or by a change in shape of the ocean basins

Question 3

Isostatic sea level change definition

Answer 3

Caused by vertical movements of the land relative to the sea

Any downward movement of land causes sea level to rise locally, while uplift of land causes sea level to fall

Question 4

Which sea level change is local and which one is global

Answer 4

Local- isostatic

Global- eustatic

Question 5

Main causes of eustatic sea level change:

2

Answer 5

1) Changes in climate
- increase in temp. causes ice sheets to melt, increasing sea level. It also causes water to expand, increasing sea level further
- opposite way for a decrease in temp.
2) Tectonic movements, of the Earths crust alter the shape ( and so volume) of ocean basins

Question 6

Main causes of Isostatic sea level change

3

Answer 6

1) Uplift or depression of Earths crust due to melting of ice sheets.
Slow uplift of land can continue over thousands of yrs after weight of retreating glacier has gone
2) Subsidence of land due to shrinkage after abstraction of ground water
3) Tectonic processes ( as one plate is forced beneath another at a plate margin )