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EROSION AND LAND LOSS
Erosion through weathering and overuse has become a serious and expensive problem. The story started some 25 million years ago with the formation of a chalk ridge which linked the Isle of Purbeck with the Isle of Wight. This ridge 'protected the soft sedimentary rocks to the north in the Hampshire Basin. 12,000 years ago during the most recent ice age the ridge was breached by active river systems. Rising sea levels flooded the area we now call Poole Bay and Hengistbury Head (which was previously a hill inland) came under wave attack.
The coastline has changed dramatically over the past 150 hundred years. An early drawing of the coast (Grose 1779) appears to show the Double Dykes intact with a curve at both ends. Presumably the stability of the headland had been maintained since Iron Age times by the accumulation of the ironstone doggers at the cliff base. Unfortunately, iron ore mining from 1850 depleted the foreshore of its ironstone, allowing the sea to attack the soft cliff sediments. This mining led to the loss of some 120 metres of coast. Land Loss between 1910 and 1990 continued (see photos of Warren Hill). Inadvertent removal of some doggers in 1980 led to serious erosion on the eastern shore - some 35 metres of coast were lost in a period of 2 years. For more information: Publications 'Hengistbury Head - The Coast
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Erosion pattern in 2010. Click on the photo to see the bigger picture.
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