Sea Level Change - Processes And Effects Flashcards
1
Q
Name the 2 types of sea level change
A
- Eustatic
- Isostatic
2
Q
Give a brief description of eustatic sea level change
A
- 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
3
Q
Give 3 facts of eustatic sea level change
A
- Global impact
- Change in volume of water stored in ice caps and oceans
- Close link to climate change
4
Q
Give a brief description of isostatic sea level change
A
- 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)
5
Q
Name the 3 landforms of submergence
A
- Rias
- Fjords
- Submerged forest
6
Q
What are rias?
A
Submerged river valleys
7
Q
How are rias formed?
A
Lowest part of river’s course and floodplain are drowned, higher land of valley sides and upper middle course remain exposed
8
Q
What is the morphology of rias?
A
- 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
9
Q
Give an example of a ria
A
Kingsbridge estuary, Devon
10
Q
What are fjords?
A
Submerged glacial valleys
11
Q
What is the morphology of fjords?
A
- 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
12
Q
Give an example of a fjord
A
Songe Fjord, Norway - 198km long and 1308m deep
13
Q
Give an example of a submerged forest
A
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
