3.8 Sea Level Change

Question 1

What are the 2 main causes of sea level change?

Answer 1

Eustatic - when the sea level itself rises or falls

Isostatic - when the land rises or falls, relative to the sea

Question 2

Eustatic change is ___________. Whereas isostatic change is _________.

Answer 2

Global

Local.

Question 3

Give an example of when isostatic change occurs.

Answer 3

During glacial periods, the enormous weight of the ice sheets makes the land sink - isostatic subsidence. As the ice begins to melt at the end of a glacial period, the reduced weight of the ice causes the land to readjust and rise - isostatic recovery.

Question 4

How has past tectonic activity had a direct impact on some coasts across the world?

Answer 4

• the uplift of mountain ranges at destructive and collision plate margins that resulted in a relative fall in sea level in some parts of the world.
• local tilting of land at destructive plate margins. Eg some ancient Mediterranean ports have been submerged and others have been stranded above sea level.

Question 5

Outline what an emergent coastline is.

Answer 5

A fall in sea level thang exposed land previously covered by the sea.

Question 6

Outline emergent coastal landforms.

Answer 6

As the land rose as a result of isostatic recovery, former wave cut platforms and their beaches were raised above present sea levels.

Raised beaches also, where the remains of eroded cliff lines can be found behind the raised beach, with wave cut notches and caves as evidence of past erosion.

Question 7

Outline how submergent coastal landforms are formed.

Answer 7

A rise in sea level floods the coats and creates a submergent coastline.

Question 8

Outline submergent coastal landforms.

Answer 8

Rias form when valleys in a dissected upland area are flooded.

Fjords are formed when deep glacial troughs are flooded by a rise in sea level. They’re long and steep sided with a U shaped cross section and hanging valleys.

Dalmatian coasts form in a landscape of ridges and valleys running parallel to the coast. When sea levels rise, the valleys flood. But the top of the ridges remain exposed, forming a series of offshore islands running parallel to the coast.

Question 9

What’s the main cause of sea level rise?

Answer 9

Primarily, the thermal expansion of water due to heating, and the melting of freshwater ice.