Auden's precious limestone faces a final break-up

"Mark these rounded slopes

With their surface fragrance of thyme and beneath

A secret system of caves and conduits; hear these springs

That spurt out everywhere with a chuckle

Each filling a private pool for its fish and carving

Its own little ravine whose cliffs entertain

The butterfly and the lizard"

In Praise of Limestone,

WH Auden May 1948

When he wrote those lines, Auden had in mind one of Britain's rarest habitats - a natural formation called limestone pavement, created by the action of prehistoric glaciers on gigantic areas of rock. But as the ink was drying on his poem, the county planners for Cumbria, Yorkshire and Lancashire took a decision that almost eradicated the unique and irreplaceable rock formations.

They handed out permission for it to be quarried for building materials and garden rockeries. Forty years later, only 3 per cent of the country's limestone pavement is untouched.

A national campaign has been launched to try to protect the rock, which sells for up to pounds 120 per tonne, from commercial pressures by encouraging gardeners and landscape designers to use other varieties.

But the idea is criticised by the only men in Britain still allowed to quarry the rock. They say the scheme, co-ordinated by the Cumbria Wildlife Trust and supported by the Nature Conservancy Council and English Nature, has come five years too late - and will encourage people to use the rock, further reducing a limited resource.

Only 2,500 hectares of limestone pavement remains in Britain. Crevices gouged in the rock by prehistoric ice provide living space for a variety of plants and animals that do not thrive elsewhere.

Almost all of it is now covered by Limestone Pavement Preservation Orders, which prohibit its disturbance - except where permission has been granted to quarry it. Only two people may now do so: Lord Lonsdale, owner of the Lowther Estate, which includes Orton Scar, 15 miles north-east of Kendal; and Alec Robinson, a Yorkshire Dales farmer, whose farm includes 14 hectares of limestone pavement.

Penny Knowles, of the Cumbria Wildlife Trust, said: "People come along at night with camouflaged JCBs and dig it up illegally. What we aim to do with this campaign is to get help from the public to find out who is taking it out and where they are selling it .... It's easily recognisable by the huge clefts, which are ideal for putting plants in."

But John Brailsford, who until recently had a contract to extract the rock at Orton Scar, says campaigners are "closing the stable door long after the horse has gone".

Mr Robinson is locked in a dispute with the Yorkshire Dales National Park, which would like to buy his area of limestone pavement in order to preserve it. His current licence to extract the rock runs until 2042. Park officials say he wants about pounds 500,000 for the land plus compensation for loss of income; they claim the commercial rate would be about pounds 150,000. The parties are at an impasse.

Meanwhile, Mr Robinson is still selling his stone. "I think this campaign will have an effect," he says.

"It will increase sales of the stone. I think it makes people more aware of it. In the past 12 months sales of stone have gone up by about 50 per cent."