There'll be bluebirds over the yellowing cliffs of Dover

SCIENTISTS SUSPECT that the White Cliffs of Dover, one of England's proudest symbols, are turning yellow - but they think the only way to find out for sure is to ask people.

Over the next year, people living along the "Heritage Coast" stretching four-and-a- half miles from Folkestone to Dover will be asked whether they think that in the past few decades the 130ft chalk cliffs, which inspired returning soldiers, pilots and Dame Vera Lynn, have become discoloured. Some observers have suggested that the cliffs look increasingly dirty. The finger is being pointed at a variety of sources - including pollution from sulphur-burning power plants in the former East Germany, diesel-powered ships or even debris from construction of the Channel Tunnel.

Clive Gilbert, environmental policy officer at Kent County Council, is less sure, however. "My favourite explanation is that the cliffs have always been a mucky, cream-greeny-grey colour. But recently there have been a number of fairly large cliff falls, exposing areas of pure white chalk. It's the juxtaposition of that with the older area which makes what was always mucky look even greyer."

Cliff collapses on the South Coast have increased lately, with the most dramatic at Beachy Head, East Sussex, last month, when thousands of tons of rock fell into the sea.

The greying of older rock is caused by algae that live on its surface, feeding on micro- organisms inside it. But yellowing might be caused by chemical reactions, especially with sulphurous compounds, at the rock's surface. Now, a council survey will ask people if they think the cliffs are indeed changing colour. Older residents' recollections will be particularly important. The survey will also ask what "value" people put on the cliffs, as part of an attempt to put some sort of price tag on their "cultural and environmental capital".