A stretch of the English shoreline where fossil-hunting first began is set to be recognised internationally as one of the richest prehistoric sites in the world.

The 95 miles of coastline between Swanage in Dorset and Exmouth in Devon, whose crumbling cliffs contain countless fossils spanning hundreds of millions of years, is likely to be named a World Heritage Site by the United Nations next week, putting it on a par with the Grand Canyon and the Great Barrier Reef.

If the bid to Unesco, the UN's cultural organisation, is successful – and all the signs are that it will be – the Jurassic Coast, as the two county councils plan to rebrand it, will become one of the world's principal geological tourist attractions.

It will be the first landscape area in mainland Britain to be a World Heritage Site, joining a plethora of man-made edifices such as Stonehenge, Hadrian's Wall, the Tower of London and Canterbury Cathedral.

The only two natural sites in the UK currently in the Unesco list, which confers instant international attention and prestige, are the Giant's Causeway in County Antrim in Northern Ireland and St Kilda, the remote and beautiful Scottish island that lies beyond the Hebrides.

The Jurassic Coast, particularly the area of tall cliffs at its centre, around Lyme Regis and Charmouth, is a unique record of 180 million years of geological time in its rock formations, and of the different life-forms that existed during each era in its fossils, which are frequently revealed by cliff falls and erosion.

"If you walk along the Dorset and East Devon coast you can walk continuously through the whole of the Mesozoic Era, which includes the Triassic, the Jurassic and the Cretaceous Periods," said Professor Denys Brunsden, a retired professor of geomorphology at King's College London. Professor Brunsden, whois chairman of the Dorset Coast Forum, has spent seven years organising the Unesco bid. "Because the rocks are sloping downwards, if you walk horizontally along the beach you can walk through time for 180 million years. It's the only place on earth where you can do that," he said.

The fossils, Professor Brunsden said, range from the time when the dominant animals were fish, through the reptiles, through the dinosaurs, through the birds and into the age of mammals.

"You can walk along and record the entire history of the environment and the species of the different periods," he said. "This is easily the richest short stretch of coastline in the world for fossils."

Serious fossil-collecting first began at Lyme and Charmouth with Mary Anning (1799-1847), who found the first specimen of Ichthyosaurus, the large fish-like lizard, the first nearly complete example of the Plesiosaurus and the first British Pterodactyl (the early proto-bird).

The daughter of a cabinet- maker who died leaving his family destitute, Ms Anning ranged along the unstable cliffs looking for fossils to sell to gentleman-collectors, and eventually became an expert on fossils herself as well as a national celebrity.

The bid for World Heritage Status for the Jurassic Coast has the backing of the Government.

Unesco's 17-strong World Heritage Committee will rule on the application in Helsinki, Finland, next week.