coastal systems -sea level change (isostatic and eustatic)

Question 1

what is sea level used for?

Answer 1

.used to identify the boundary between the land and sea

Question 2

how many years are the glacial period cycles?

Answer 2

.every 100,000

Question 3

when was the last glacial maximum?

Answer 3

.18,000 years ago

Question 4

what were sea levels on average at the last glacial maximum?

Answer 4

.110m below their current level

Question 5

what have sea levels risen to since the last glacial maximum?

Answer 5

.sea levels have risen close to 140m
.averaging 10mm rise every year

Question 6

what are the 2 types of change regarding sea level?

Answer 6

.eustatic
.isostatic

Question 7

what is eustatic change?

Answer 7

.change in the relative level of land and sea due to rises and falls in the global sea level

Question 8

what is isostatic change?

Answer 8

.the rise or fall of land in relation to the sea level -this is localised

Question 9

what are the 2 possible causes of eustatic change?

Answer 9

.thermal expansion of water
.changes in ice sheet extent

Question 10

how might thermal expansion be a cause of eustatic sea level change?

Answer 10

.as water is heated it expands so even if the mass of the ocean stays the same warmer water has a larger volume so takes up more space and sea level therefore rises

Question 11

how might changes in ice sheet extent cause eustatic sea level change?

Answer 11

.where ice forms on land during a glacial period it removes water from other stores eg -hydrosphere, so sea levels fall so when ice on land melts there is less water locked in the cryosphere so more water is available to other stores eg-ocean (hydrosphere) and therefore sea levels rise

Question 12

what are the 2 causes of isostatic change?

Answer 12

.glaciation
.post-glacial readjustment

Question 13

how might glaciation cause isostatic sea level change?

Answer 13

.during an ice age glaciers
and eventually ice sheets form over the land in areas cold enough -this causes the land surface to become pressed into the upper layer of the mantle (the asthenosphere) and therefore relative sea level rises

Question 14

how might post-glacial readjustment cause isostatic sea level change?

Answer 14

.following the melting of ice sheets and glaciers on land the land is able to rise back up as the asthenosphere rebounds

Question 15

what is isostatic rebound responsible for?

Answer 15

.falling sea levels in Scotland today as during the last ice age Scotland was the part of the UK covered with the thickest ice and it melted last

Question 16

what evidence is there of eustatic fall over the last 18,000 years?

Answer 16

.at the end of the last ice age, sea levels were at their lowest as less ice could reach the oceans as it was frozen on land

Question 17

what evidence is there of eustatic rise over the last 18,000 years?

Answer 17

.10,000 years ago, the ice began to melt so sea levels rose

Question 18

what is the evidence of isostatic rise over the last 18,000 years?

Answer 18

.the weight of the ice on the land increased so large land masses sunk under the pressure

Question 19

what evidence is there of isostatic fall over the last 18,000 years?

Answer 19

.as the ice melted, the weight of the ice on land masses decreased so they began to uplift