And so, from here back to Lulworth, the path stays within a few metres of the clifftop all the way. The first time I walked this coast, it was the end stretch of a long hike from the Bristol Channel to Old Harry Rocks at Swanage by way of Cheddar Gorge, the cathedral city of Wells, Sherborne Abbey and the Dorset Downs. This section along the chalk cliffs to Lulworth, and on through the Lulworth firing ranges, struck me not only because of its wide seascapes and sculpted rocks, but also because of being jolly hard work. A series of steep chalk valleys have been sliced right across by the sea, for a coastline path that goes steeply up to a bit of teetering along the brink, then steeply down again, all ready for another steeply up.
On a hot August afternoon, this was as tiring as any Scottish mountain; and the massed cars of Lulworth's car park made a sun-gleaming inland sea to match the real sea on the other side.
But now in early springtime, the one or two beach walkers were in padded jackets rather than bikinis. The wind was chilly and fresh, and the summer car park just a battered green field. Normally I end a walk here at the Lulworth Crumple. No, it's not the moment of thankful relaxation as you collapse into the sand with your end-of-walk ice cream dribbling over your sweaty fingers. It comes about ten minutes before that, a splendidly squashed-up bit of sea cliff, pierced below by a mini-Durdle Door.
But this evening, Pete the photographer leads out of a different corner of the car park to his own favourite endpoint: a place called Dungy Head. It's a grass-topped knob of crumbly limestone, looking back along the coastline we've just been walking over.
Around the curve of the bay, sea-cliffs rise one behind the other: Durdle Door, Swyre Head, Bat's Head with the tiny hole through at sea level; and fading against the sky, the slope of White Nothe displaying the exact steepness of the smugglers' path we came up four hours before. The sun makes a golden streak across the slate-blue sea, and the cliffs gradually fade in the salt haze thrown up by the breakers at their foot.
Peter scurries about finding dangerous looking outcrops to take photos from, at the same time making picturesque shapes himself against the darkening sky. And then it's time to just sit on the grass, through what Pete calls the Blue Hour ("cos yes, you can get some good blue-y ones too"). And watch the pastel shades in the sky, and the sea, and a strange lenticular cloud like a smuggler's cloak over the hump of Portland on the other side.
All right, so the Jurassic Coast may not be the thinnest World Heritage Site. Hadrian's Wall beats it that way, and so does the Pontcysyllte Aqueduct. (Come to think of it, those two are pretty good to ramble along as well.) But when it comes to a grand bit of walking, with a feet-on demonstration of hard science thrown into the mix, there's only two words for it.
Fantastic. And Jurassic.