0:00:02 > 0:00:07A good map will show us where we are and help us on our journeys.
0:00:07 > 0:00:12A better map will transform the way we see the landscape around us.
0:00:12 > 0:00:16But in 1815, a map was published which did much more than that.
0:00:16 > 0:00:19It gave us a new means of understanding Mother Earth.
0:00:21 > 0:00:26The geological map of England and Wales peeled back the soil
0:00:26 > 0:00:30and, for the very first time, showed what lay beneath.
0:00:30 > 0:00:35The map was all the work of one man - William Smith.
0:00:35 > 0:00:40And the end result of that work was cataclysmic.
0:00:40 > 0:00:44The truth about the formation of the Earth began at last to emerge.
0:00:44 > 0:00:51I'm going to take a journey from the Bristol Channel, across the West Country, to the English Channel.
0:00:51 > 0:00:55My quest is to discover exactly how Smith's map
0:00:55 > 0:01:01transformed the way the British people thought about their own island.
0:01:28 > 0:01:32In 1815, as the Napoleonic Wars drew to a close,
0:01:32 > 0:01:37William Smith published his geological map of England and Wales.
0:01:37 > 0:01:43For the first time anywhere in the world, Smith's map revealed the geology of a whole country.
0:01:43 > 0:01:48But it wasn't the work of an academic geologist.
0:01:48 > 0:01:52William Smith was a working man - a West Country surveyor -
0:01:52 > 0:01:56and he struggled for more than 25 years to have his ideas accepted.
0:01:56 > 0:02:02Smith's map was the product of practical observations as he went about his business,
0:02:02 > 0:02:07but making it entailed an enormous paradox - to understand the map on the horizontal axis,
0:02:07 > 0:02:12you have to understand what's going on deep under the ground.
0:02:12 > 0:02:17So a geologist like Smith doesn't see what the rest of us see.
0:02:17 > 0:02:21He feels the world through the soles of his feet.
0:02:21 > 0:02:24To a man like Smith, walking along, his eyes cast down,
0:02:24 > 0:02:28none of this beautiful surface geography would exist.
0:02:28 > 0:02:32It's all been peeled away. It's just a decorative veneer.
0:02:32 > 0:02:34He'd be looking for these - stones -
0:02:34 > 0:02:37because every stone tells a story.
0:02:37 > 0:02:39These were the voices Smith heard
0:02:39 > 0:02:42from his subterranean world.
0:02:45 > 0:02:51My journey begins in a place Smith knew well - the Forest of Dean in Gloucestershire.
0:02:51 > 0:02:58On his map, its carboniferous rocks are marked in black. In his day, the forest was booming.
0:02:58 > 0:03:04There was a fortune in the trees, as they were harvested for Nelson's navy.
0:03:04 > 0:03:08But it was booming for another reason. As the 18th century ended,
0:03:08 > 0:03:13England was undergoing an economic transformation - the Industrial Revolution -
0:03:13 > 0:03:17and that depended on minerals and the rocks beneath the earth.
0:03:17 > 0:03:21- I'll see you down by the entrance. - Yeah. I won't be a moment.
0:03:21 > 0:03:27The early 1800s were a time of intense intellectual and economic ferment.
0:03:27 > 0:03:32The part played by Smith was to apply science to the furtive business of mineral prospecting.
0:03:32 > 0:03:37In the world of prospecting, there was one cash-rich rock above all.
0:03:37 > 0:03:43It was black, it was dirty, it burned brightly, and it came from holes like this.
0:03:43 > 0:03:49- God, it's wet and cramped down here. - Not to worry. - How do you get used to this?
0:03:49 > 0:03:55Not the sort of place to be if you don't like filth, mud, running water and pitch dark, is it?
0:03:55 > 0:04:01'This coal mine in the Forest of Dean was started in the 1820s on the advice of Smith himself.
0:04:01 > 0:04:07'But how did he know where the coal was? Nick Evans still works this mine with five colleagues,
0:04:07 > 0:04:12'and although the technology's a bit different, conditions here haven't changed much since then.'
0:04:12 > 0:04:17The style of working and the supports will be as it was in Smith's time.
0:04:17 > 0:04:21All this on the side is what we call marl.
0:04:21 > 0:04:27And the marl's a dangerous stuff, which is why you've got to have these supports holding it all up.
0:04:27 > 0:04:31- It's a fairly unstable material, yes. We'd better make our way back up.- OK.
0:04:31 > 0:04:37'Even then, when labour was cheap, searching for coal was enormously expensive,
0:04:37 > 0:04:41'and if you didn't find coal, you could lose a fortune.
0:04:41 > 0:04:46'So everyone wanted to find a way of knowing where the coal was, and that's where Smith came in.'
0:04:46 > 0:04:49This is the coalface.
0:04:49 > 0:04:54'The coal is concealed in several layers of different rocks.'
0:04:54 > 0:04:58- Oh, yeah.- Here, right at the very top, we've got the sandstone.
0:04:58 > 0:05:01- That's this layer here? - That's this here.
0:05:01 > 0:05:05Then, underneath that, you've got the marl.
0:05:05 > 0:05:09- So that's the junction between the sandstone and the marl there?- Mm-hm.
0:05:09 > 0:05:12And then here, the coal.
0:05:12 > 0:05:18- Underneath the coal, there's this clay.- That's this gungy, sticky stuff?- Yes.
0:05:18 > 0:05:21So there are four layers all within about a metre here.
0:05:21 > 0:05:28'In 1791, when he was just 22, Smith was asked to survey some coal mines just like this,
0:05:28 > 0:05:34'in Somerset. There, the young man made his first revolutionary discovery.
0:05:34 > 0:05:38'He noticed that the layers of rock above and below the seams of coal
0:05:38 > 0:05:43'always occurred in exactly the same order wherever you were.'
0:05:43 > 0:05:49- The black layer, the coal, that's always going to be lying underneath the marl. Is that right?- Yes.
0:05:49 > 0:05:52So wherever you've got marl, go down a layer, you'll find coal?
0:05:52 > 0:05:56- Correct.- Which is what William Smith must have known.
0:05:56 > 0:06:02He didn't have to go underground to know where the coal was. He'd look for outcrops of marl.
0:06:02 > 0:06:07'But it was confusing. Many rocks looked similar to each other.
0:06:07 > 0:06:11'How could you be sure that a rock really was what you thought it was?'
0:06:11 > 0:06:14Occasionally, we come across these.
0:06:15 > 0:06:20That is the root of one of the giant tree ferns that formed the coal.
0:06:20 > 0:06:26'This root has been preserved and turned to stone by time and the pressure of the rock.
0:06:26 > 0:06:28'It's a fossil.'
0:06:28 > 0:06:32- The long-lost forest comes to light again.- Oh, yes.
0:06:32 > 0:06:37'It's very difficult for us today to realise how ignorant people were in Smith's day about fossils.
0:06:37 > 0:06:43'With their bizarre, often symmetrical patterns and strange shapes,
0:06:43 > 0:06:46'these were regarded as wonderful, curious stones.
0:06:46 > 0:06:52'They were given exotic names, like thunderbolt, devil's toenails, snake stones,
0:06:52 > 0:06:58'and they were all put there, of course, on the third day of Creation by God himself.
0:06:58 > 0:07:03'So they weren't extinct animals at all. They were religious relics.'
0:07:04 > 0:07:10But these extraordinary stones held the key to mapping underground Britain.
0:07:14 > 0:07:17As he tramped the country for his employers,
0:07:17 > 0:07:23Smith noticed that you found one kind of fossil in one rock layer and another in a different layer.
0:07:23 > 0:07:27But why? How did that connection work?
0:07:27 > 0:07:33To find out, I'm going to follow Smith back towards his native Oxfordshire, into the Cotswolds.
0:07:43 > 0:07:48On this side of the Severn, the Cotswold hills
0:07:48 > 0:07:52come crashing down in a steep escarpment to the plain below.
0:07:52 > 0:07:57It's the perfect place to investigate one of Smith's most important discoveries.
0:07:57 > 0:08:02Smith was the first man to recognise the value of fossils
0:08:02 > 0:08:06as a means of identifying particular layers of rock.
0:08:07 > 0:08:12It may seem hard to believe today, but once, millions of years ago,
0:08:12 > 0:08:16the entire height of this escarpment was under the sea.
0:08:16 > 0:08:21In fact, the whole of it is made of rocks
0:08:21 > 0:08:26created by the steady accumulation of material on the sea floor.
0:08:26 > 0:08:30Rocks like this are known as sedimentary rocks,
0:08:30 > 0:08:36and they were laid down at different times as evolution progressed and species evolved.
0:08:36 > 0:08:38So if there are fossils in them,
0:08:38 > 0:08:43the species of fossil present will identify the rock exactly.
0:08:43 > 0:08:46No matter how far apart two outcrops of the same rock were,
0:08:46 > 0:08:50the fossil groups in them should be similar.
0:08:50 > 0:08:54Now I'm going to put Smith's big idea to the test.
0:08:58 > 0:09:03This is the rock that was laid down 170 million years ago,
0:09:03 > 0:09:07when this part of England was covered by a shallow, warm ocean.
0:09:07 > 0:09:13And on the bed of that ocean, all sorts of things like coral and scallops were growing.
0:09:13 > 0:09:15So where shall I start?
0:09:15 > 0:09:21All I'm looking for are oysters, in particular, cos there should be lots of those around here.
0:09:21 > 0:09:27There we are. Here's a broken oyster shell, and here's another one. If I can get those out intact...
0:09:28 > 0:09:33..which I can't. Oh, there it is. That's pretty good.
0:09:33 > 0:09:36There's another. I'll get that one out.
0:09:36 > 0:09:38There we go.
0:09:40 > 0:09:46Both those have got a bit shattered, but let's try this one here.
0:09:46 > 0:09:48We'll get a better example.
0:09:48 > 0:09:50Eureka!
0:09:50 > 0:09:51Fantastic!
0:09:51 > 0:09:54Incredible.
0:09:54 > 0:09:56Look at this.
0:09:56 > 0:10:01This is a really good oyster. 170 million years old.
0:10:01 > 0:10:05That's three times as old as the dinosaurs. Now, according to Smith,
0:10:05 > 0:10:12I should find this family of fossils all the way through this yellow band across his map.
0:10:12 > 0:10:19Before Smith's time, most people identified rocks by referring to what they were made of -
0:10:19 > 0:10:24sand or mud or lime - but Smith's method offered a far better way.
0:10:24 > 0:10:30It meant that you could distinguish between two kinds of rock, even if they looked the same.
0:10:30 > 0:10:36Now I'm going to walk right down the yellow oolitic band on William Smith's map,
0:10:36 > 0:10:40to the other end of the Cotswolds, to see if it's really true.
0:10:44 > 0:10:51Down here, outside Bath, the rocks seem to be the same kind of oolitic limestone we saw outside Cheltenham.
0:10:51 > 0:10:55The question is, will I find the same kind of fossil?
0:10:55 > 0:11:01And to make sure that everything's fair and above board, I've asked Hugh Torrens to join me -
0:11:01 > 0:11:08now a professor of geology, but a man, like Smith, who has collected fossils since he was a boy.
0:11:11 > 0:11:14Blow me! Look at this.
0:11:14 > 0:11:16It's a beauty.
0:11:16 > 0:11:22- Is that an ammonite? - Yes. That's the inner whorls... and these are the sutures.
0:11:22 > 0:11:28- Is it possible Smith walked up here, found it and chucked it aside?- He might have dropped it to confuse us!
0:11:28 > 0:11:34Smith bought a house in Somerset because this was where the work was. The area was full of coal mines.
0:11:34 > 0:11:39What Hugh and I are going to do is to put Smith's idea to the test -
0:11:39 > 0:11:43the idea that fossils can identify the rocks.
0:11:43 > 0:11:49- This hole was actually excavated by Smith himself.- Smith dug this?! - Yes. This is rather a sacred spot.
0:11:49 > 0:11:53Is it possible that he chipped some fossils out of this oolite?
0:11:53 > 0:11:59Well, in his collection in London, he records fossils from this rock - the Inferior Oolite -
0:11:59 > 0:12:05- from his house there.- Here, let me get my fossil out. Here it is. Here's my oyster.- Right.
0:12:05 > 0:12:09- Is this oyster from the same group of fossils?- The same stratum? Yes.
0:12:09 > 0:12:13- This is Inferior Oolite, Smith's Bath stone.- And here's...
0:12:13 > 0:12:16That's an oyster.
0:12:16 > 0:12:19- This oyster lived with my oyster? - Yes, yes, yes.
0:12:19 > 0:12:25- Same group of fossils?- They are of the same period in time, in the same rock unit.- 14 miles apart.- Yes.
0:12:25 > 0:12:29- Thousands!- It's packed with fossils, until you get to the sand,
0:12:29 > 0:12:36then the fossils become different and rather rare. His work as a mineral prospector has been ignored.
0:12:36 > 0:12:41Until you know the order of rocks, you can't work out where you are.
0:12:41 > 0:12:46Smith was the first person to order the rocks of the whole country,
0:12:46 > 0:12:50from the capital to the source of its main fuel, coal.
0:12:50 > 0:12:56So he went from London clay right down to the carboniferous, down to where the main money was made,
0:12:56 > 0:13:00and he was able to tell them, "You can find that here."
0:13:00 > 0:13:07But he was more able to say, "You'll NEVER find that there. Stop trying, you're wasting lots of money!"
0:13:07 > 0:13:11- There's a crinoid stem. - Oh, yes. What's a crinoid stem?
0:13:11 > 0:13:16It's a sea lily. Like a student, it sits rooted to the ground with its mouth open, expecting to be fed!
0:13:16 > 0:13:22What made Smith more extraordinary was that he was doing this at a time
0:13:22 > 0:13:26when people were only just realising how old these rocks were.
0:13:26 > 0:13:32I don't think Smith had any real realisation about the can of chronological worms he was opening,
0:13:32 > 0:13:34but he certainly opened the can.
0:13:34 > 0:13:38Other geologists asked, "If this sequence is so thick,
0:13:38 > 0:13:44"can we use the thickness to work out how long it might have taken?" The first estimate, in Smith's lifetime,
0:13:44 > 0:13:50was that it must be a million years because we know how slowly mud in the Bristol Channel is being deposited.
0:13:50 > 0:13:57We have several thousand feet of thickness. Do your sums. You come to at least one million years.
0:14:02 > 0:14:07At the time Smith was working here, the Church of England laid down
0:14:07 > 0:14:11that the world was created at nine o'clock in the morning
0:14:11 > 0:14:14on the 23rd of October 4004BC.
0:14:14 > 0:14:19That, said the bishops, was what the Bible tells us.
0:14:19 > 0:14:24So Smith's new geology was rather unsettling.
0:14:24 > 0:14:30Even Smith was a bit perplexed. He wrote in his diary about time testing the faith of many,
0:14:30 > 0:14:35but his quest was still firmly practical.
0:14:35 > 0:14:39For him, the map was the thing... not the whys and the wherefores.
0:14:39 > 0:14:45The first thing that strikes you when you look at this map today is how exquisitely beautiful it is.
0:14:45 > 0:14:51But it may not have looked quite like that to the first people who saw it in Smith's day,
0:14:51 > 0:14:56because this is a map which has exposed the innards of Britain.
0:14:56 > 0:15:01Many people would have looked at this as if they were looking inside their own body for the first time.
0:15:01 > 0:15:06What we're seeing here are the working parts of an island.
0:15:06 > 0:15:13Anybody wanting to make the most out of Britain's own natural resources need only look at this map.
0:15:13 > 0:15:15The colours tell the whole story.
0:15:15 > 0:15:20The yellow band of oolite down here... Fantastic building material.
0:15:20 > 0:15:24New towns and cities springing up during the Industrial Revolution.
0:15:24 > 0:15:27The blue marl here for brick-making.
0:15:29 > 0:15:33These coloured... The chalk areas green,
0:15:33 > 0:15:37ideal for putting on lime-deficient fields to improve crop yields.
0:15:37 > 0:15:42And, of course, the chalk of Britain is largely pasture, which is green.
0:15:42 > 0:15:48And the black over here in South Wales, the coal - the fuel of the Industrial Revolution.
0:15:48 > 0:15:53The fascinating thing is that these colours were, on the whole,
0:15:53 > 0:15:58adopted as the international standard for geology maps,
0:15:58 > 0:16:04so Smith set the template for the colour in geological maps with this great masterpiece.
0:16:04 > 0:16:10Above all, this is a map for the new industrial Britain, the pumping heart of a world empire.
0:16:26 > 0:16:32By now, Smith had effectively established the basis of modern geological technique.
0:16:32 > 0:16:37He knew that rocks were arranged in layers under the ground.
0:16:37 > 0:16:42He knew that you could identify those layers using the fossils.
0:16:42 > 0:16:46But how was he going to prove that there was more to it than that?
0:16:46 > 0:16:49That the sequence of layers was consistent everywhere?
0:16:49 > 0:16:54At this point, he found himself to be the right man in the right place.
0:16:54 > 0:16:57He'd come to Somerset to survey coal mines,
0:16:57 > 0:17:03but in the booming industrial expansion, there was another way a surveyor could make his mark -
0:17:03 > 0:17:05canals.
0:17:05 > 0:17:11For Smith, who was both a surveyor and a geologist, this was a fantastic, historic opportunity.
0:17:13 > 0:17:19This overgrown industrial relic is where Smith's ideas about the layering of rock were confirmed.
0:17:19 > 0:17:24In 1794, 25-year-old Smith - young, ambitious, driven -
0:17:24 > 0:17:29got a job surveying the route of the new Somerset Coal Canal.
0:17:29 > 0:17:34There were two branches of the canal right here, about ten miles apart,
0:17:34 > 0:17:39and it gave him a fantastic opportunity to conduct his own geological experiment.
0:17:39 > 0:17:44As the navvies cut down through the surface of the earth,
0:17:44 > 0:17:48and before these facing stones had been put on locks like this,
0:17:48 > 0:17:53Smith was able to look at the layers of rock, and pick the fossils out.
0:17:53 > 0:17:57What he found was that the layers and fossils in this cutting
0:17:57 > 0:18:03matched up with the layers and fossils in the cutting ten miles over there.
0:18:03 > 0:18:09From this moment on, Smith knew for sure that wherever you stood in England and Wales and Scotland,
0:18:09 > 0:18:15the layers of rock would be the same, and THAT was the basis of his great geological map.
0:18:17 > 0:18:21Smith's experiment had confirmed all his theories.
0:18:21 > 0:18:24If you wanted to cut a canal or sink a coal mine,
0:18:24 > 0:18:30it was no use loosely identifying the layer of rock on the surface and then digging down.
0:18:30 > 0:18:36You had to understand exactly what layer you were on, and where it came in the sequence.
0:18:36 > 0:18:41His success made it possible for him to warn prospectors with confidence
0:18:41 > 0:18:45about where to sink their mines and build their canals,
0:18:45 > 0:18:50but by the end of the 1790s, Smith's ambitions were beginning to embrace the whole of England,
0:18:50 > 0:18:56and elsewhere, he might not have the convenient opportunities he'd had in Somerset.
0:18:56 > 0:18:59There was another way, though.
0:18:59 > 0:19:05To make his map, what Smith needed to do was to relate the sequence he had found in the Somerset coalfield
0:19:05 > 0:19:09to those he found on hillsides in the rest of England.
0:19:09 > 0:19:14He did it by constantly travelling, as I am, close to the ground.
0:19:14 > 0:19:18Smith knew that, even if the rock layers themselves were consistent,
0:19:18 > 0:19:23the particular rock you found at the surface varied from place to place.
0:19:23 > 0:19:28In other words, you wouldn't always find the same rock at the top.
0:19:28 > 0:19:35So wherever he went, Smith took detailed notes about what he found on his travels.
0:19:35 > 0:19:39Here, at Glastonbury, is one of those places.
0:19:39 > 0:19:45According to Smith's notes, there was a simple sequence of layers going up the hill outside the town.
0:19:45 > 0:19:48But if only geology was always that easy!
0:19:48 > 0:19:54The rock layers on this hill are horizontal, but in other parts of the country, it's more complicated.
0:19:54 > 0:19:59Smith's encyclopaedic recording of the rocks never stopped
0:19:59 > 0:20:02and it led him to a remarkable discovery.
0:20:02 > 0:20:07The sequence of layers he'd found in the rocks below the earth
0:20:07 > 0:20:11seemed to be repeated on the ground as he travelled across the country.
0:20:11 > 0:20:17After Lias, the limestone, then the green sand, the chalk and the clay, as you went eastwards.
0:20:17 > 0:20:19At first, this was puzzling.
0:20:19 > 0:20:25Why should the vertical sequence of layers be repeated in the horizontal as well?
0:20:25 > 0:20:30But then he was struck by a brilliant analogy to explain it.
0:20:30 > 0:20:36Now, if geology was really simple, England would look like the monster sandwich that I'm going to eat,
0:20:36 > 0:20:43with the youngest rocks on the top - the chalk - and the older rocks down below, but Smith had a revelation.
0:20:43 > 0:20:47He realised that England's rocks had tilted, rather like that,
0:20:47 > 0:20:51and that something had exposed the older rocks down below,
0:20:51 > 0:20:55so that as you travelled from east to west across England,
0:20:55 > 0:21:02you crossed successive outcrops of rocks. And that's exactly what you see on Smith's map,
0:21:02 > 0:21:05with the younger rocks in the east, progressing across
0:21:05 > 0:21:10to the older rocks in the west. Smith had made a profound discovery.
0:21:10 > 0:21:16What he'd recognised was that the sequence of rocks he'd identified going down into the earth
0:21:16 > 0:21:21was, because of the tilt, replicated across the face of England, as well.
0:21:21 > 0:21:28So he was able to include a little cross-section diagram on his map, which showed how the sequence lay.
0:21:29 > 0:21:35But where could you actually see the evidence for that idea? And how could Smith prove it?
0:21:35 > 0:21:40The obvious place is, of course, on the south coast of England,
0:21:40 > 0:21:46where the ceaseless crashing of the Channel tides has carved away the rocks for all to see.
0:21:46 > 0:21:49And it's less than 50 miles away.
0:21:50 > 0:21:55On the Dorset coast, you can see some of the most beautiful seascapes
0:21:55 > 0:21:59in the world, but it's more than just a pretty sight.
0:21:59 > 0:22:04It's become crucial to the geologists' view of the world.
0:22:04 > 0:22:07But had Smith sorted out the geology of England?
0:22:07 > 0:22:13Not a bit of it! His layers were about to receive the shock of their lives.
0:22:13 > 0:22:18Well, here I am on top of Golden Cap, one of the most popular playgrounds in southern Britain.
0:22:18 > 0:22:25It lies roughly midway along the most spectacular geological coastline...probably in the world.
0:22:25 > 0:22:31In the hundred or so miles between the River Ex down there and the Isle of Purbeck along there,
0:22:31 > 0:22:36you can walk across 185 million years of the Earth's history,
0:22:36 > 0:22:42from the sandstones and mudstones in the west, towards the younger limestones and chalk in the east.
0:22:42 > 0:22:48So if I take a walk now eastwards, I should cross successive layers of rock that get younger and younger,
0:22:48 > 0:22:54but I've a sneaky feeling, and so did Smith, that geology is not quite as simple as a sandwich.
0:23:01 > 0:23:07This part of the English coast has been designated a World Heritage Site.
0:23:07 > 0:23:12It provides almost a complete sequence of the sedimentary rocks
0:23:12 > 0:23:16laid down between 250 and 66 million years ago.
0:23:16 > 0:23:24So as you walk eastwards, you cover at least a million years for every mile you walk.
0:23:25 > 0:23:30And because some parts of the sandwich are softer than others,
0:23:30 > 0:23:35the sea has got in in some places and played merry hell with the rocks.
0:23:35 > 0:23:41But you also begin to realise that the layers haven't just been tilted and left to erode.
0:23:41 > 0:23:44Something much more dramatic has happened.
0:23:46 > 0:23:49And if we look at Smith's map,
0:23:49 > 0:23:54we can see that, true to form, William Smith realised that something odd was going on.
0:23:54 > 0:23:59It's clear that this coast was not just made of simple layers of rock.
0:23:59 > 0:24:05Here in the Isle of Purbeck, Smith's east-west progression has become a north-south one.
0:24:13 > 0:24:17Well, this is the famous Lulworth Crumple.
0:24:17 > 0:24:23It's a brilliant example of what can happen when savage forces fold the surface of the Earth.
0:24:23 > 0:24:27All those layers of hard rock have been folded over on themselves,
0:24:27 > 0:24:31like so many slices of bendy cheese and ham.
0:24:31 > 0:24:38It almost looks as if my clean-cut geological sandwich has had a very bad day in the rucksack.
0:24:38 > 0:24:41How did those rocks get like that?!
0:24:41 > 0:24:47Smith and his contemporaries were still only coming to terms with the real age of their rocks.
0:24:47 > 0:24:52The cataclysmic events which led to the folding of the Lulworth Crumple
0:24:52 > 0:24:55was something they couldn't ever have imagined.
0:24:57 > 0:24:59But Denys Brunsden can.
0:24:59 > 0:25:06He's spent his whole life working on this coast, analysing every cliff and landslide.
0:25:06 > 0:25:12It was largely because of his efforts that this coast was declared a World Heritage Site.
0:25:12 > 0:25:18If anyone can tell us what happened to Smith's neat layers of rock, he can. It's an astonishing story
0:25:18 > 0:25:23'of crashing continents, volcanic mayhem and upended rocks.'
0:25:23 > 0:25:25We've actually got a bay
0:25:25 > 0:25:28cutting across the grain of rock.
0:25:28 > 0:25:32When you look at the William Smith map, they're running this way.
0:25:32 > 0:25:35We're just looking at the end now.
0:25:35 > 0:25:40We can see that, instead of the rock gently dipping, they're right up on end, like that.
0:25:40 > 0:25:47- Sticking up vertically.- Here, they're almost overturned and we've just got the gem of the Dorset coast.
0:25:47 > 0:25:51- One of the gems of the British coast!- Or of any coast! Durdle Dor.
0:25:51 > 0:25:55- It's glorious. That's why it's World Heritage.- We get younger that way,
0:25:55 > 0:25:59but it's because the rocks, instead of being like that, are like this.
0:25:59 > 0:26:06Millions of years ago, the solid rock of Dorset was twisted and bent by huge geological events.
0:26:06 > 0:26:12- The whole of the Earth's crust was on the move.- It's the force of Africa moving north,
0:26:12 > 0:26:17hitting Europe, of course, and much further south, forming the Alps.
0:26:17 > 0:26:24But those stresses were still being felt up here. It's very confusing. Very difficult to work out.
0:26:24 > 0:26:29- So, we've got a gigantic collision between two of the Earth's plates... - A long way to the south.
0:26:29 > 0:26:35- ..but the ripples reached the whole way to Britain.- Yes. The outer ripples of the Alpine storm.
0:26:35 > 0:26:37LOUD CRASHING
0:26:39 > 0:26:43To William Smith, who had no conception of this kind of turmoil,
0:26:43 > 0:26:49a place like this must have been an absolute nightmare, but, even so,
0:26:49 > 0:26:55his techniques are still completely valid. Smith's map was crucial in working out what happened,
0:26:55 > 0:26:59as it gave people a concrete picture of the layers beneath the soil.
0:26:59 > 0:27:04It was Smith who provided the hard data for others to analyse.
0:27:04 > 0:27:08He's actually producing evidence of great forces in the Earth
0:27:08 > 0:27:13that have tilted something that was horizontal and stood it on end,
0:27:13 > 0:27:19and I think, for those practical geologists, he was providing a whole systematic way
0:27:19 > 0:27:26of these complicated things that you have to observe, and suddenly they were into theories of Earth.
0:27:26 > 0:27:30It's setting up great principles. They were doing something new.
0:27:30 > 0:27:36It was a wonderful, wonderful time. Tough, but a nice place to be.
0:27:40 > 0:27:44It was on this very coast that the discoveries were made
0:27:44 > 0:27:48which established the modern science of geology.
0:27:48 > 0:27:53Here, the first dinosaurs were identified, as well as an entire fossil forest.
0:27:53 > 0:27:57Even today, this coast is vital for geological research,
0:27:57 > 0:28:04but over it all hovers the spirit of William Smith, the first man to conceive of its true nature.
0:28:04 > 0:28:09Smith's genius was to recognise that the age-old practice of map-making
0:28:09 > 0:28:15could be applied to the subterranean world, a world which was invisible to all but himself.
0:28:15 > 0:28:21But this humble, systematic foot-slogger created more than a map.
0:28:21 > 0:28:25Smith's monumental work laid the foundation for future scientists
0:28:25 > 0:28:29to understand the structure of the Earth itself.
0:28:38 > 0:28:44Subtitles by Susan Mason BBC Broadcast 2004
0:28:44 > 0:28:48E-mail us at subtitling@bbc.co.uk