Isostatic Rebound
During the last ice age vast quantities of ice lay across the United Kingdom with the thickest, and thereby the heaviest, laying across Scotland and northern England. The huge weight of this ice mass slowly pushed the land downwards into the earth’s mantel which, much like a see-saw, forced the lower half of England to rise up. After the ice retreated, and the weight was lifted from the northern lands, the see-saw began to move back in the other direction with Scotland slowly rising and southern England slowly sinking back down to it’s former level.
This process continues to this day with the rate of adjustment currently estimated to be 1 - 1.5mm per year along the Essex coastline (1). This isostatic rebound or readjustment is compounding the problems of sea level rise due to global warming and is partly responsible for the levels of coastal erosion around the Essex coast.
Evidence of how Essex was lifted up out of the sea can be seen in the cliffs at Walton-on-the-Naze. For years fossils hunters of all ages have scoured the area at the bottom of the Naze cliffs for fossil sharks teeth that have been exposed by erosion of the cliffs. It should come as no surprise then that if the cliffs are full of marine fossils then this area was once beneath the sea. Isostatic rebound will, over the next few thousand years, replace many of these uplifted sea beds back beneath the waves with sea level rises only helping to speed the inevitable.
References
(1) Hughes R G, Paramor O A L, 2002, The Effects of Biological and Physical Processes on Saltmarsh Erosion and Restoration in SE England, http://www.tyndall.ac.uk/research/theme4/workshop1/chapter_5.pdf.
