Environmentalists have warned that plans to extract a rare stone will leave a heavily-protected stretch of coastline like a "lunar landscape".
Permission to quarry the valuable Portland stone on the Isle of Portland, Dorset, was issued in 1951 before the area was declared a Unesco World Heritage Site, a Site of Special Scientific Interest, a European Special Area of Conservation and a Regionally Important Geological Site.
The stone was needed to rebuild bomb-shattered buildings during the Second World War but the coastal strip site has not yet been excavated.
The planning permission remains valid until 2042 and Stone Firms Ltd, the company that owns the site, now plans to extract 140,000 cubic metres of stone, worth an est imated pounds 77million over the next 30 years, from a strip of land about 10ft away from the cliff face.
The firm said it has just six months' supply of stone left in its other Portland quarries.
It will take 30 years to dig about 40 ft down across the 50-acre site, and the work will guarantee 80 jobs.
But more than 2,000 people have signed a petition against the work and others have written to the National Trust to persuade the charity to buy the land and safeguard it for future generations.