Sea Level Change - Processes And Effects

Question 1

Name the 2 types of sea level change

Answer 1

• Eustatic

- Isostatic

Question 2

Give a brief description of eustatic sea level change

Answer 2

• During cooler glacial periods e.g. Pleistocene (last ice age), more water is store as ice on land
• Sea levels were 100 metres lower than present
• Holocene (current warm period), eustatic sea levels have risen due to rising temperatures melting water sore as ice caps and glaciers
• Present eustatic sea levels are rising by 2 millimetres, due to melting ice and thermal expansion

Question 3

Give 3 facts of eustatic sea level change

Answer 3

• Global impact
• Change in volume of water stored in ice caps and oceans
• Close link to climate change

Question 4

Give a brief description of isostatic sea level change

Answer 4

• During Pleistocene mass of ice sheets caused land to ‘sink’ into mantle
• Caused sea levels to increase isostatically, but counter acted by greater eustatic fall
• Since beginning of Holocene weight of ice has been released and isostatic readjustment has occurred
• E.g. NW Scotland rising up to 7mm per year and SE England sinking (seesaw effect)

Question 5

Name the 3 landforms of submergence

Answer 5

• Rias
• Fjords
• Submerged forest

Question 6

What are rias?

Answer 6

Submerged river valleys

Question 7

How are rias formed?

Answer 7

Lowest part of river’s course and floodplain are drowned, higher land of valley sides and upper middle course remain exposed

Question 8

What is the morphology of rias?

Answer 8

• Shallower water, becoming deeper towards the middle
• Exposed valley sides are gently sloping
• Long profile is even, uniform water depth
• Plan view; winding, reflecting rivers original course

Question 9

Give an example of a ria

Answer 9

Kingsbridge estuary, Devon

Question 10

What are fjords?

Answer 10

Submerged glacial valleys

Question 11

What is the morphology of fjords?

Answer 11

• Steep, cliff like valley sides with uniform deep water (over the 1km depth)
• Cross section; U shaped, reflecting original valley
• Long profile; shallowest water is seaward end
• Plan view; straight due to glacier truncating interlocking spurs

Question 12

Give an example of a fjord

Answer 12

Songe Fjord, Norway - 198km long and 1308m deep

Question 13

Give an example of a submerged forest

Answer 13

Borth, Wales

• Buried under peat bog 5,000-6,000 years ago due to rising sea levels
• Discovered in 2014 when winter storm stripped away covering peat and sand
• Lack of oxygen preserved wood in almost pristine state