Lulworth Crumple, Stair Hole, Lulworth Cove and then on to Durdle Door

Following our visit to Corfe Castle and lunch at the Scott Arms we headed off to Lulworth to see the cove and the crumple. Now this sort of thing is just so interesting. It's kind of like having a geology lesson that you can walk through. And it's not just me: more school children come to Lulworth on geography field trips than go to any other corner of the country.

So what's the Lulworth Crumple, you ask?

Well, here it is. This magnificent cliff face with the layers of rock all playing off at jaunty angles to the horizontal is the Lulworth Crumple.

Lulworth Crumple and Stair Hole

The rocks here are sedimentary, and, as you might expect, they once lay in nice, neat, horizontal layers made up of hard limestone alternating with soft mudstone.

The Crumple was produced when the tectonic plates carrying Europe and Africa crashed into one another about 65 million years ago. The force of the impact folded up parts of the land to form the Alps and the Pyrenees after a fashion that was not totally dissimilar to the way in which a car hood - or bonnet, as we like to call them in England - will bend in a head-on collision.

Shock waves spread out across the plates, like ripples in a pond, pushing up smaller hills like the chalk ridges in Purbeck. As the layers of rock at the Crumple were pushed against each other under the impact of those shock waves they bent so that some of the originally horizontal layers are now almost vertical, but the different types of rock performed differently under the huge pressures to which they were subjected. The hard limestone bent and cracked, but remained largely intact. Gravity caused the soft mudstone to slide between the harder layers of limestone to fill any spaces produced where it had bent. In this way the amazing folds that are the Lulworth Crumple were formed.

Lulworth Crumple and Stair Hole

Stair Hole is the big hole in the spine of hard Portland limestone that faces out to sea. It's been formed by sea erosion of a weakness in the rock, which is slowly, slowly producing a circular sea cove behind it that will one day, in the distant future look like Lulworth Cove, just over the other side of the headland. In fact it will probably merge with Lulworth Cove as a result of continued coastal erosion.

Would you like to see the famous Lulworth Cove?

Here it is:

Lulworth Cove, Dorset

It's a perfect, almost fully circular, cove. It was formed where a river, swollen with melt water at the end of the ice age wore its way down through the hard, almost vertical rock strata of Portland limestone, directly in front of the sea. Behind this hard rock were bands of much softer rocks backed by a harder band of chalk (which you can see, rising up from the beach). As a result when the channel, which had been opened up by that old river, was exposed to the ebb and flow of the sea, the soft rocks between the limestone and the chalk were eroded much more rapidly than the hard rocks in front, or the chalk behind. Diffraction of the sea waves as they bunched together to pass through the narrow opening at the mouth of the cove and then spread out afterwards caused the circular erosion. If you look carefully at the photos you can just about see the circular wave forms resulting from this diffraction.

Lulworth Cove, Dorset

And you can still see the remains of that big old river that caused the whole thing to develop in the first place. These days it's more of a fast-flowing stream, but it runs down past the beach café where they sell teas and ice cream to the tourists.

The entrance to Lulworth Cove, Dorset

And then we drove off round the coast a little further to see the wonders that are Durdle Door and the Man O'War Rocks, which are to be found in the cove to the east of Durdle Door.

You can see the Man O'War Rocks in the photo below. A very, very long time ago the cove here looked a lot like Lulworth Cove, but sea erosion eventually wore away the spine of hard limestone that faced out to sea, and the Man O'War Rocks are all that remains of that old limestone spine. Look carefully ... you can still see the large hole in the centre, through which the sea entered and which caused the wave diffraction that produced the circular cove. And if you look even more carefully you can see how the waves are still diffracting through that opening to come out rounded. There's a bit of interference with waves coming through the other openings, but the diffraction is still pretty clear.

Man O'War Rocks, Dorset

Anyway, on over the headland is the famous Durdle Door, formed by sea erosion of a weakness in the limestone spine that faced out to sea.

Isn't it amazing?

When we were there a multitude of people were dressed in wet suits to swim through the arch. Others were climbing up the outer pillar and jumping into the sea. Can you see one of them, brave soul, in the photo below?

Emi thought that was the very coolest thing he'd seen anyone do in ages. And I prayed quietly that he'd forget about it, and not want to repeat the trick himself any time soon ... .

If you'd like to visit I'd advise you to wear strong shoes. You can easily walk down the steps to the Man O'War beach, but you have to climb down the cliff to get to the Durdle Door beach, and it's a bit of a scramble.

Access to Durdle Door Beach, Dorset

All the best,

Bonny x

And if you're down in this neck of the woods why not visit some other cool Dorset delights? There's:

Corfe Castle (just down the road)

The Scott Arms (great tucker and a view to die for)

Or, for something completely different, the Tank Museum, Bovington, which isn't very far away either.