The South East of England is gradual tilting downwards, London is sinking at the rate of 300mm (one foot) every 100 years and Scotland is raising. In the Ice Age, land weighed down under 1500m of ice sank by over 100m. Land round the edges (like north France and southern England) rose in compensation - like a see-saw. When the ice melted, the fairly rigid land mass took time to return to its original
levels - so much so, that Kent is still slowly sinking back. This causes long-run worries for sea-flooding. Much of the low-lying coast on either side is protected by seawalls, which can be breached if there's a storm at high tide. Where the land behind is former marshland, it may be 0,5m below mean sealevel.
To counter the flooding risk associated with this tilting and sinking, the Thames Barrier was built across the Thames at Woolwich at a cost of around £535 million in 1983. It was built to protect London in the event of a one in 2000 year flood. The chance of such a flood has already doubled, with climate change and sinking land this will continue to get worse. They are already talking about further flood protection. Some are talking about moving people to higher ground.
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