Paddling with Devon's dinosaurs

The weather conditions were prehistoric. The mud was Triassic, the rain Cretaceous and mobile phone reception generally Neolithic. But then, magnificent places generally reduce mobiles to useless lumps of plastic.

I was on Britain's Jurassic Coast. This 95-mile coastline stretching from Dorset to Devon has been elevated to the status of a global cultural treasure by Unesco, ranking it along with the Grand Canyon and the Taj Mahal ... which was why I found it so disturbing to come upon a poster warning me to go no further on pain of death, illustrated with a pair of smoking hiking boots.

One of the prime sections is occupied by the Ministry of Defence's Lulworth firing ranges, and anyone who wants to walk with the dinosaurs must first check whether the flags are flying, or they might be joining the dinosaurs sooner than expected.

The region's World Heritage significance lies in the seams of rock which break the surface here, yielding huge quantities of information about 185 million years of existence. I would add that the cliffscape can be stunningly beautiful and that, unlike most of the rest of the highly suburbanised south coast, parts of it are remarkably wild. Jurassic, even.

I started my coastal roam chez Kevin Keates, a craftsman-quarryman at Worth Matravers above Swanage. I'd met Keates years before when he'd discovered 104 diplodocus footprints in his quarry. I wanted to ask him what difference he thought World Heritage status would mean.

He wasn't holding out great hopes. Not that he thought the World Heritage status was undeserved. "This coast is like reading a wonderful history book, but you have to understand the language," he said. A tourist would need a guide. Were there any? Keates shook his head; not as far as he knew.

The loveliest stretch is between Swanage and Weymouth, with geological highlights that even muggins can understand, such as Durdle Door, where great tramlines of rock rear up out of the sea, Lulworth Cove, and Lulworth's Fossil Forest. But this is also the most inaccessible part and not only because of the MoD ranges. A combination of swirling hills and feudal farming estates has kept roads and development well away from the shoreline, and the only way to appreciate it is to leg it along the Southwest Coast Path.

As you approach Weymouth there's an unfortunate tendency to fill scenic spots with caravan sites. Then there's Chesil Beach, undoubtedly a landscape wonder but it's very hard to walk ankle deep in small stones. The Jurassic Coast is most accessible at Lyme Regis, part smuggler's port, part elegant Georgian spa and part tacky seaside resort. This is the place to lay your hands on hard evidence of what the World Heritage designation is all about.

Several locals lead fossil walks from Lyme, and the pounding surf creates potential new discoveries at every tide. At least if you pick something up on the beach here it won't blow you up, as it might do at Lulworth. If you're in the right place at the right moment, it might well blow you away.

For further details go to www.jurassiccoast.com or call the visitor manager on 01305 225091.