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sea level change - Coggle Diagram
sea level change
eustatic change- a global change in sea level resulting from an actual fall or rise in the level of sea.
However, since the Pleistocene the ice has melted and returned to the hydrosphere meaning that our sea levels have risen again.
thermal expansion is due to global warming. As the global temperatures increase so does the temperature of the sea. As the sea warms up it also expands resulting in the sea level rising.
During the Pleistocene 10,000 years ago much of the water froze. Snow and ice act as a store for water so the hydrological cycle slows down. As a consequence, sea levels fall over the whole planet- eustatic fall. During the pleistocene the sea level was 120meters lower than today.
Submergent features
fjord
As a glacier comes down a valley it carves out a U shaped valley. When the glaciers melt and the sea levels rise water goes up and flood the valley. They often have hanging valleys too where rivers have been disrupted and now create waterfalls. Fjords are straight with no tributaries. There is often a shallower section at the end called a threshold where the glacier lost its energy. For example Sorgne fiord is Norway which is 4 miles wide.
rias
Drowned river valleys. As sea level rises it can flood the river valleys, leaving to only the high land visible e.g. Falmouth. The rias in the South East of England are shallower as the land is made out of clay. This means that due to flocculation the sediment builds up, creating shallower rias. examples include Falmouth in Cornwall which has now been utilised as a port.
dalmatian coast
Forming on concordant coastlines when the sea erodes through a small section of the hard rock creating a cave. Over time this will continue to be eroded until it reaches the soft rock. The soft rock is much quicker to erode and the sea will flood it. However, the elongated stacks of hard rock still remain. Such as the coast of Croatia.
Isostatics change- local changes in sea level resulting from the land rising or falling relative to the sea
During the Pleistocene the ice laden north sunk under the weight of the ice (isostatic subsidence) while the south rose up (isostatic rebound). However, now as the ice has melted the opposite is happening with the south sinking and the north rising. e.g. Land in northern Scotland is rising by 2mm/yr.
Tectonic movement such as the creation of large volcanos can also lead to the sea rising as the water is displaced.
Emergent features
relict cliffs
Caves, stacks and stumps that have been created by erosion but since have experience isostatic emergence and no longer near the sea meaning they have become extinct.
raised beaches
Raised beaches are areas of former wave cut platforms and their beaches. As the land has risen the beaches rise with it meaning the sea can no longer reach it. There are many in Scotland which can reach hights of 10 meters.