Enquiry Question 3: How do erosion and sea level change alter physical characteristics of coastlines?

Question 1

Eustatic change

Answer 1

Global sea level change associated with ice-age activity (e.g. formation of ice, melting of ice sheets).

Question 2

Isostatic change

Answer 2

Local changes in land height relative to sea level. This can be attributed to tectonics activity, subsidence and and post-glacial rebound.

Question 3

Tectonic activity

Answer 3

Movement of tectonic plates (e.g. thrust fault) can lift or lower land in relation to sea level.

Question 4

Post-glacial adjustment

Answer 4

After the melting of ice sheets, the land slowly rebounds over thousands of years. This process can slowly lift land out of the sea.

Question 5

Subsidence

Answer 5

The sinking of the land - causes coastal land to be submerged. This can be caused by the over-abstraction of groundwater supplies, mining and erosion (e.g. erosion of deposited sediment on deltas).

Question 6

Accretion

Answer 6

Deposition of coastal sediment leads to ‘crustal sag’ under the weight of the sediment (slow process).

Question 7

Emergent coastline

Answer 7

Sea level drops relative to land, exposing former sea bed.

Question 8

Submergent coastline

Answer 8

Land is flooded and the coastline is ‘drowned’..

Question 9

Coastal recession

Answer 9

The erosion of coastlines at a rapid rate, resulting in loss of land, homes and businesses.

Question 10

Dredging

Answer 10

Scooping/sucking sediment from the sea/river bed. This deepens the sea/river bed to allow larger boats to pass.

Question 11

Coastal Management

Answer 11

Using hard engineering/soft engineering to modify, or adapt to, coastal processes.

Question 12

Vegetation removal

Answer 12

Deforestation of plants/trees, such as mangrove forests, removes a natural coastal defence system. This can increase the likelihood, and severity, of coastal erosion and flooding.

Question 13

Storm surge

Answer 13

The rising of the sea as a result of wind and atmospheric pressure changes associated with a storm. This results in higher than normal tides, and tsunami-like flooding.

Question 14

Depressions/cyclones

Answer 14

Areas of low air pressure are associated with strong winds, high rainfall and storm surges.

Question 15

Flooding

Answer 15

Cover or submerge an area with water

Question 16

What causes a EUSTATIC fall in sea level?

Answer 16

Glacial periods (every 90,000 years) cause the earth’s climate to cool. More precipitation falls as snow and is stored as snow and ice (glaciers and ice sheets). Less water flows through the water cycle, so sea levels fall (reduced volume of sea water).

Question 17

What causes a EUSTATIC rise in sea level?

Answer 17

Interglacial periods cause a warming of the climate which melts snow and glaciers and more precipitation falls as rain. Rain and snow/ice melt runs off in to the oceans, causing a rise in sea level (increased volume of sea water). Thermal expansion also contributes to rising sea levels.

Question 18

Thermal Expansion

Answer 18

As oceans become warmer due to global warming, sea water expands slightly, contributing to rising sea levels.

Question 19

What causes ISOSTATIC rise in sea level?

Answer 19

Post-glacial adjustment, accretion and tectonics.

Question 20

What causes ISOSTATIC fall in sea level ?

Answer 20

Post-glacial adjustment, subsidence and tectonics.

Question 21

What is Isostatic Subsidence?

Answer 21

During ice ages the weight of the ice sheets makes the land sink.

Question 22

What is Isostatic Recovery/Rebound?

Answer 22

As the ice begins to melt at the end of a glacial period, reduced weight of the ice sheets causes the land to readjust and rise.