Man has interfered so much with the landscape in the English countryside that it is hard to comprehend and measure how natural changes to climate and sea levels have altered the geography. However, recent aerial photographs of the Wash and areas of low lying land in Norfolk and Lincolnshire show an enormous network of criss-crossing natural drainage systems.
The explanation for these is the alternate rise and fall of sea levels during Neolithic and Bronze Age periods. Each time the sea rose and dropped again, a new set of channels to drain the marshes evolved and then silted up. These were invisible below the surface level under several metres of peat, but modern farming methods and fen drainage have caused the land to shrink so much that what were once the beds of ancient rivers now stick up above the surrounding land.
Some ridges are half a mile wide and 2 metres higher than the surrounding peat, making it possible to record and map them. The shrunken peat beds are now on average 2 metres below sea level, while the former riverbeds are 0.3 metres above; so in a flood, they would form a refuge.
The geologists' maps of this area, now potentially at risk from a catastrophic North Sea storm, are scary. They would be classed as alarmist if published in a tabloid paper. King's Lynn, Boston and Wisbech would be under the sea and Peterborough, Lincoln and Cambridge would be coastal towns.
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