Sea level change


Eustatic Change:

How the levels of water in the sea changes. During the Ice Age, sea level was at least 120m lower than it is today. Much of the water was stored as ice, either over land areas or extending over the sea. At the end of the Ice Age, temperatures rose and the ice melted, raising sea levels. More recently, global warming has led to sea level rise. This is due to glaciers/ice sheets melting but also because of thermal expansion. 

Isostatic Change:

Land raising or falling in relation to the sea. During the Ice Age, much of the British Isles was covered with ice, but anything south of London and Bristol wasn't. This extra weight in the north pushed the northern Britsh Isle downwards and the south rose slightly. But now, the ice has melted so the isles tilt the other way. The North and Scotland are rising so have features of emergence and the South is sinking so the coastlines will be of submergence. 


Ria= Drowned river valley, flooded from rising sea levels, leaving only the high land visable. In S-W England they are large and the slopes are steep as the rivers flow of the resistant rock granite. This rock means there is little material deposited in the channel so it creates a natural deep habour. In S-E England they have been filled with 15m of alluvium (loose sediment), so this creates shallow esturaies which expose mud banks at low tide. 

Fjord= This is a drowned glacial valley, which sees U-shaped valleys submerged as sea levels rise and flood the valleys glaciers have left. They have very steep sides and are fairly straight and narrow. They have hanging valleys over each side. The mouth has a shallower section called a threshold, which is thought to be where glacial erosion was reduced as the glacier came into contact with the sea. These are confined to higher latitude regions which were once glaciated (Norway, Southern Chile, Alaska, Britsh Columbia, South Island of New Zealand). Fjords (in Norway) interestingly have some of the largest coral reefs found at the…


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