The Needles: Isle of Wight Coast

On this restless coastline, everything's on the move, even the land.

The Isle of Wight seems so permanent and immoveable, and yet it's on a monumental journey.

Nick Crane's crossing the Solent, in search of where the island's been,

and what's happened to it

along the way.

Sailing around the Isle of Wight you get some sense of its size.

At 23 miles across, it's England's largest island.

It seems like a lost world.

In fact, it's a time capsule containing

clues to a journey the whole of the British Isles has been on.

On a lost world you'd hope to find dinosaurs, and you wouldn't be disappointed.

This is a dinosaur footprint,

the beach is absolutely littered with them,

they've fallen out of the cliff above me as the sea has eroded.

It belongs to a four- or five-tonne Iguanodon.

Look, you can see one articulated toe here, here's another one,

the third toe has been snapped off, and here is the heel.

These massive beasts tramped along this beach 130 million years ago,

except that back then this land wasn't even here.

And that's because the Isle of Wight has been on the move for ages, geological ages.

And the evidence of its epic voyage is everywhere.

This chalk is created from the remains of plankton which died

78 million years ago in a very warm, very clear tropical sea.

There certainly aren't tropical seas here now, so where was the Isle of Wight when the chalk was laid down?

Well, a lot further south, and at the time it wasn't

even an island.

10,000 years ago it was part of the landmass of Britain.

Step back 10,000 more and Britain was attached to the European mainland,

but rewind a colossal 135 million years to the time of the dinosaurs

when the continents were a lot closer together, Europe was 1,000 miles further south than now.

The Isle of Wight has seen a lot of action on its journey north,

and not surprisingly has picked up a few knocks along the way.

You can see the bruises from those knocks in the landscape.

Overlooking the multi-coloured cliffs at Alum Bay,

geologist Alasdair Bruce is helping me get my eye in.

What we're looking at it the huge fold in the Earth's crust.

So if I elaborate by showing you this, that is essentially what we're looking at end-on.

So this bit of the book is that peninsula sticking out in the sea?

Yeah, those horizontal beds in the distance,

and as you come further into the bay and into the Alum Sands themselves, they've now been tilted vertically.

-And that's the vertical part.

-That's the centre.

-This bit here?

-Indeed.

-OK. So what caused the fault?

Well, millions of years ago when Africa thundered into Europe to create the Alps.

These are the plates covering the planet that shift around.

Constantly moving. And as a result of that collision

we all had to make way, geologically speaking, and our contribution

in Britain was this large fold, and this essentially forms the backbone of the Isle of Wight.

Switzerland got the Alps, the Isle of Wight got the fold.

The chalk ridge running the length of the Isle of Wight, is in fact the last ripple of a colossal shockwave,

the result of a continental car crash between Africa and Europe 65 million years ago.

But even that didn't dislodge the Isle of Wight from the mainland of Britain,

and you can still see the evidence of where it was connected, at The Needles.

Alasdair, can you describe exactly what we'd have seen 10,000 years ago

if we'd looked from here towards what is now Dorset?

We'd have seen a line of white chalk cliffs, and behind that you'd have had cliff tops

covered in primitive grasses, and as you walked away from that sort of coastal environment,

you'd have walked into ancient woodlands and slowly down to shores of the estuary of the River Solent.

-Sounds like a paradise.

-Indeed.

So how did that woodland paradise become an island?

20,000 years ago, Northern Europe and most of Britain

was covered with a layer of glacial ice over a mile thick.

It started to warm up, the ice melted and water levels rose,

but that wasn't the only thing that helped create the Isle of Wight.

The other process is best illustrated by two men with an inflatable bed.

OK, this is a primitive United Kingdom, we're going to have Scotland at one end,

-and the Isle of Wight on the other end.

-This is the North?

It is, and it's very malleable as you can see.

-So you're saying that the surface of the planet is this bendy in places?

-Yes, geologically speaking.

20,000 years ago, Scotland was covered with two kilometres thick of ice,

-an enormous amount of weight, and I want you to be that weight, so in you go.

-I'm Scotland, covered in ice.

If I bring in the Isle of Wight, put that in place,

then we wind the clock forward to about 12,000 years ago,

the glaciers are melting away from Scotland really rapidly, so off you get.

This drops, sinks down a bit, that is called "isostatic rebound".

But what's happened to the Isle of Wight is, not only have we got sea levels attacking it,

sea levels rise from all the glacial water going into the sea,

but you've got the isostatic rebound happening, so the sea is now going to come churning around this particular

lump of rock and turn it into the Isle of Wight that we see today.

So it's being hit by a double-whammy.

It was this combination of rising sea levels and the sinking landscape

that would eventually separate the Isle of Wight from the mainland.

The sea was rising, biting away at this chalk cliff,

and at the same time the River Solent doing its thing at the back,

so there would come a point where it would become a very narrow knife-edge blade

going out across the sea, and then finally one stormy night it was breached, and the sea

basically flooded into this area, and got rid of what was the River Solent.

It took a few thousand years before the Isle of Wight was totally cut off as we see it today,

but that's a blink of the eye compared to its multi-million-year trek,

and this restless traveller is still moving, still evolving,

part of the epic journey that the whole of the British Isles is on.

'I'm also off out to The Needles.

'It's not great conditions for studying rocks, but it is good for MY passion.

'This is after all the sort of weather lighthouses were made for,

'and I enjoy a good lighthouse, me!'

So I couldn't resist a visit to this one, on The Needles,

especially when I found out they're about to clean the lens.

Everything about a lighthouse reminds us that we are connected to other shores.

'Even the specialist lens used in lighthouses is an invention from across the Channel from France.'

-How often does the lens get cleaned, then?

-Just once a year.

It's going to take about that long.

I'd hate to be responsible for a smear.

This really does feel like the edge of Britain,

but of course the light from here continues on, travelling far beyond our shores and actually

crossing the beam of the Gatteville lighthouse on the French coast.

Even the light wants to bridge the gap.

It kind of makes you want to reach out yourself and meet the neighbours.

Subtitles by Red Bee Media Ltd