Exploring West Sussex geology
with David Bone
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The structure of the Wealden anticline can be seen from many viewpoints along the South Downs. The slope of the hills to the south reflect the surface of the beds as they gently arch up and over towards the central Weald before descending again to form the North Downs. The centre of the Weald has been deeply eroded as the uplift was taking place. If not, the hills may have reached a height of 900 metres (3000 feet).

It may be difficult to believe how much erosion has taken place but you have to remember that we are talking about millions of years. Also, in more recent geological time, the severe climatic fluctuations of the Quaternary (the ‘ice age’) would have accelerated the rate of erosion.

Evidence of instability introduced by rapid erosion during the ‘ice ages’ is seen at places like Older Hill, where much of the hillside is a massive landslip. The landscape is still slowly readjusting itself to new conditions.

Occasionally, nature ignores the more recent attempts of mankind to make its mark on the landscape. The Chichester floods in 1993 and 2000 resulted from the River Lavant taking to its former route to the sea via Pagham Harbour. The photograph is of the A27, just east of Chichester. The route that the River Lavant currently follows to Chichester Harbour is undoubtedly a Roman or medieval diversion to take water to the city and waste from it.