How have Chines formed?
Chines are formed by the rapid erosion of soft clays and sands caused by water flowing out to sea. Imagine standing on the cliff top anywhere along the ‘Back of the Wight’ and looking out to sea. Standing on the same spot thousands of years ago, you would have been looking out across dry land, with the coastline somewhere out on the horizon. There would have been a series of river valleys starting from the high points of the downs behind you, probably flowing into a much longer Western Yar, then into the Solent River and on to the sea.
Over time, sea levels have risen and the coastline has been continually eroding and retreating backwards through the soft rock, leaving a line of cliffs along the coast and cutting short the rivers. With a short distance from source to sea the force of the water cuts deep into the soft cliffs producing the steep-sided narrow gullies which we know as chines. This process of stream erosion can be quite fast moving. Shepherds Chine eroded down 15 metres in 150 years – that’s about the width of this book eroding down every year.
Why are chines where they are?
Chines have formed in the parts of the Island where water emerging high above sea level has only a short distance to go over soft rocks before it meets the sea coupled with a rapid rate of coastal erosion caused by high energy waves and wild Atlantic storms.
The position and angle of some of the Isle of Wight Chines, especially Shippards, Brook and Shepherd’s Chines suggest they are cutting down into lines of ancient weaknesses caused by deep faults in the geology below.