"Every year, the resorts of the Mediterranean are a magnet for holiday makers in search of peace and relaxation." "But there's another side to the story." "The geological forces that create stunning locations like this extraordinary crater, these dazzling limestone terraces," "and these awe-inspiring rockscapes, also bring death and destruction." "When we take our holidays in the Mediterranean, we are actually visiting one of the most geologically dangerous places on Earth." "I'm going to take a geological tour of the Mediterranean's beauty spots, so I'll be sidestepping the tour guides." "I want to tell a different story." "By explaining the forces which make the Med such a dangerous place," "I'm going to solve some of the region's most baffling mysteries." "What was it that brought the greatest civilisation the world has ever known to its knees?" "How did the inhabitants of a Greek island escape from the most devastating volcanic eruption?" "And what could really explain the apocalyptic destruction of the Biblical cities of Sodom and Gomorrah?" "It's all down... to the rocks beneath our feet." "My search for answers to the mysteries of the Med starts here, in Turkey... ..the bridge between Europe and Asia." "Istanbul is one of the world's greatest cities, the former capital of two great empires." "First the Byzantine, then the Ottoman." "Its rich cultural heritage and colourful street life attracts visitors from all over the world." "But I've got a different agenda from your typical tourist." "As you know, Turkish carpets are beautiful." "I really don't want a carpet." "Can't carry them." "I'm looking for rocks, actually." "That's very nice." "It's Turkish Delight." "Turkish Viagra." "Viagra!" "I'd better not eat any more." "If you're a tourist, you'll be entranced by the sights and sounds of this hustle and bustle." "But if you're a geologist like me, you'll be searching for clues to explain the region's turbulent geological history." "One of the jewels in Istanbul's crown is the Ayia Sophia, "The Church Of The Divine Wisdom"." "It's one of the greatest surviving examples of Byzantine architecture." "The building actually first started to be constructed at the end of the 4th century AD." "For nearly a thousand years, the Ayia Sophia was the largest enclosed space in the world." "On the minaret, there's Arabic writing." "It says "Allah" - the name of God." "The Ayia Sophia is a magnificent building, with its domed basilica, its stunning mosaics, and its beautiful columns." "But sidestep the tourist throngs, and you can find clues to what, for me, is a much more interesting story." "Leaning columns." "An arch that's been twisted." "Cracked sunken floors." "And the massive dome has collapsed on at least two occasions." "For a geologist, these are the telltale signs of the violent activity in the rocks below, which has menaced Ayia Sophia throughout its 1,500-year history." "This remarkable building and the vast city of Istanbul, sit right in the middle of a notorious earthquake zone." "The threat of catastrophic disaster is a constant fear." "The underlying forces which make Istanbul and regions of Turkey so vulnerable, are the same as those that make the rest of the Med so perilous." "And I'm going to show you why." "Now, the Earth's surface is broken into a set of enormous plates." "And they move around on a semi-molten mantle of hot rock beneath them." "Now, the African plate has been grinding against the European plate for the last few million years, and stuck in the middle of both is poor old Turkey." "Although these plates move roughly at the rates my fingernails grow, the forces involved are absolutely awesome." "The thing about rocks moving together is that they tend to get stuck." "As they move, the strain builds up until a critical point is reached, then everything goes altogether." "And that is what causes an earthquake." "Turkey actually has a giant cobweb of fault lines criss-crossing it, and I'm walking on one of them." "On this side, this grassy bit here, is soft sediment." "But on this side is hard rock, and separating the two, is a beautiful earthquake fault." "Look - the block of rock that was once here has slid down this surface, creating these incredible scratches." "These weren't made by human hands or a mechanical excavator." "These are earthquake marks." "Millions of people in Turkey live under the threat of one of the most treacherous faults on the planet." "It's the North Anatolian fault, slicing through the top of the country for over 1,000 kilometres." "In the last 100 years alone, there have been 11 major earthquakes along this fault line." "And one of the most devastating was in 1999, and it happened just down the road." "At three in the morning, on August 17th, a violent earthquake ripped apart the industrial city of Izmit." "It lasted just 45 seconds - time enough to kill 25,000 people, injure 44,000 and damage or destroy nearly 300,000 homes." "It was Turkey's most devastating earthquake in the last 60 years, and caused movements along a 120-kilometre section of the North Anatolian fault." "Directly in its path was this petrol station." "And here, the North Anatolian fault runs right beneath my feet." "On this side, we've got the Turkish plate." "And on this side, we've got the European plate." "You see the...the front edge of this building here?" "Well, that was originally lined up with the edge of this building here." "It's moved one, two, three, four-and-a-half metres." "And this line of pumps here was originally flush with this line of pumps here." "And the quake has shifted it, one, two, three, four-and-a-half metres." "And the edge of this forecourt here was flush with the edge here." "So it has moved, one, two, three, four-and-a-half-metres." "Now, the amazing thing was that under this one there's a petrol tank and under this one there's a petrol tank." "And the earthquake rupture ripped right between the two." "A few metres either side, and this place would have been totally obliterated." "Although the worst may now be over for Izmit, the threat of similar devastation nearby is highly probable." "Because once a fault has ruptured, the stresses are transferred further along the fault line." "And slap-bang in the firing line - 56 kilometres to the west of Izmit - is a city of 15 million people " "Istanbul." "Ironically, the fault lines which threaten Istanbul have brought opportunities elsewhere." "The huge network of cracks in the ground act as pathways for all kinds of stuff to rise to the surface." "And it's not all bad." "Pamukkale, in Southern Turkey, is home to one of the most remarkable geological landscapes in the Mediterranean." "It's a dazzling fairyland of bleached terraces, which the Turks call "Cotton Castle"." "Since Roman times, these mineral-rich waters have attracted visitors in search of good health." "But Pamukkale hasn't always been so tranquil." "None of this extraordinary landscape would be here if it wasn't for fault lines in the rocks below." "The surrounding countryside is riddled with them." "I'm walking inside a giant crack in the Earth's surface." "Deep below, the Earth is like a geological cooking pot." "Below the Earth's crust, a semi-molten hot mantle is heating up ingredients like gas and minerals and water, that want to get to the surface." "And it's the pathways created by cracks like these that provide the escape route." "The land around Pamukkale is predominantly limestone and very porous." "So when rain falls, it penetrates the rocks." "Decaying plant material on the surface makes the rainwater acidic, so as it seeps underground, it carves channels through the limestone." "Eventually, the water - by now saturated in the dissolved ingredients of limestone - is heated up by hot rocks below and forced back up to the surface." "And it gets there by rising up through cracks and fault lines." "This is where the water bubbles up to the surface from the rocks below." "It comes out from these springs, it tumbles down the cliff and then it spills out over this cascade of pools." "It's absolutely fantastic." "As the water surges over the edge, the limestone is deposited on the terraces." "This process has been going on for at least 14,000 years." "And the spas of Pamukkale are as popular today as they were in Roman times." "These waters are absolutely laden with dissolved minerals, and are supposed to be good for a whole range of problems." "I mean, look at this here." "Look, minerals are things like calcium and magnesium and gases we get, stuffed full of carbon dioxide." "And down here, the waters are even radioactive." "And in terms of the diseases these waters are supposed to help, well, we've got obesity, we've got gastritis, we've even got constipation." "I think I should get my trunks on." "See what this is like." "Oh, it's quite warm!" "Oh, this is beautiful." "Do you think these waters are good for you?" "Ah, yeah, quite good." "You're feeling better?" "Well, somewhat." "We're feeling younger, OK." "It's relaxing." "You're relaxing." "I was here two years ago and my hair was silky and my skin was very soft." "Right." "Smell the water." "Do you like that smell?" "It's like water." "Smells a bit funny." "It's got radioactivity, it says." "It's very high in radioactivity." "I think it's very low radioactivity, according to the table." "Right." "It's very low." "That makes me feel much better." "As I said before, cracks in the rock don't just bring up good stuff, they bring up bad stuff as well." "And you don't have to look far to see the darker side of Pamukkale." "Near the spas of Pamukkale are the ruins of the ancient Roman city of Hierapolis..." "..destroyed by a series of severe earthquakes." "This was one of the most sacred buildings in Ancient Hierapolis - the temple to the God Apollo." "After nearly 2,000 years and numerous earthquakes, very little of it survives." "But a cave on which the temple foundations rest does survive, along with its ominous reputation." "The cave was called the Plutonium and was a sacred shrine to Pluto " "God of the Dead and of the Underworld - and the Ancient Greeks thought it led straight to Hell." "Any living creature that entered the cave died instantly." "It was a mystery to which geology holds the key." "Today, the cave lies behind this wall." "Apparently, in ancient times, it was impossible to see the floor of the cave because it was so thick with vapours." "And this is a clue." "This deadly cave was full of poisonous gas." "And it still is." "You can hear water and gas bubbling away, and that's why this is bricked up so that nosy people like me don't get gassed." "And where did all this gas come from?" "Well, as ever, from the rocks below." "The water deep in the limestone is full of the poisonous gas - carbon dioxide, which is picked up from that decayed plant material." "In the rocks, pressure keeps the gas dissolved in liquid, just like the gas in this fizzy water." "But when earthquakes open cracks in the rock... the liquid gas comes to the surface, and because it's not under pressure, it escapes into the air." "That's fine if you're up here with plenty of oxygen to breathe, but if you're down there in Pluto's cave, it's another matter." "Once the deadly carbon dioxide was released from the rocks in the cave, it had nowhere to go." "Heavier than air, it would have sat like a cloud poisoning anyone who entered." "Of course, cracks in the earth are not just pathways for water and gas." "I'm heading south now to show you something else that passes up through faults to the earth's surface." "And it may hold the key to solving one of the Mediterranean's greatest mysteries." "Here, in Jordan, on the fringes of the Med, the collision between the African and European plates has created an austere but stunning landscape." "This region is the site of some of the most momentous events in Biblical history." "Many people believe that somewhere around here were the ancient cities of Sodom and Gomorrah." "The Old Testament tells us that God wiped both cities off the face of the earth in an apocalyptic act of vengeance because its inhabitants were just so wicked." "It's a story so powerful that it's lasted for thousands of years." "But is there any truth in it?" "As a geologist," "I'll look to the rocks for answers to the mystery." "And there's no better place to start than the Dead Sea, where one rock in particular plays a crucial role in the story." "The Dead Sea is one of the most remarkable tourist attractions in the Middle East." "400 metres below sea level, it's the lowest place on Earth." "Here, the water is six times saltier than the world's oceans, which means it's incredibly difficult to swim." "Fed by the Jordan river, the Dead Sea has no outlet and over thousands of years, the sun has evaporated the water, leaving behind a syrup of minerals." "The sea is rich in chloride salts of sodium, magnesium, potassium and bromine." "And the salt haze over the water filters out most of the sun's dangerous UVB rays, so tanning is much safer." "And when you tire of sunbathing..." "Is that mud?" "Yeah." "..you can always have a therapeutic massage." "Look at that!" "Looks like mud." "Does it look OK?" "I don't look silly?" "No." "How does that look?" "The unique properties of the Dead Sea are the direct result of the massive forces constantly at work beneath our feet." "It lies in the Rift Valley - the meeting point between two great tectonic plates." "That's the African one over there, and this is the Arabian one." "They're slowly moving apart from each other." "As a result of this plate movement, the earth's crust around here is being stretched thin, causing the area of the Dead Sea to sink down." "This instability causes earthquakes and fault lines." "Look, across there is a fault line." "See those purple rocks on the left?" "If you trace the top of them across, when it gets to the fault line, it drops down by four to five metres." "That drop would have been caused by several big earthquakes, and that's exactly what's happening out there in the Dead Sea." "If Sodom and Gomorrah really existed in this part of the world, then the geology here confirms that they would have been vulnerable to earthquakes." "Quakes here were big enough to have left the cities partly destroyed, but not annihilated as the Old Testament claims." "We need to search for something that's more than just shaky ground... something catastrophic." "Today, it's tourists who float happily on the surface of the Dead Sea." "Millions of years ago, you'd have seen something far more curious." "The seabed was a mass of chemical compounds formed from decayed plant material and animal matter." "When earthquakes opened up cracks in the seabed, compounds were released, and one of them was especially valued." "It came up like this... asphalt." "In Biblical times, it must have seemed like a gift from the gods." "It was really useful stuff." "Long before the invention of cement, asphalt was used to put stone blocks together." "It was great for throwing up buildings." "But one of its most valuable uses was as a waterproofing agent." "This bucket's got a nasty leak in it." "Let's see what asphalt can do." "Oh, that's cooking nicely." "It's gas mark five, but to be honest, I wouldn't try this at home." "OK, let's see if it works." "Hey-hey!" "100% waterproof." "Well, almost." "Now, if you lived on these shores thousands of years ago, you probably wouldn't have needed to repair too many buckets, but asphalt would have been great if you wanted to waterproof your boat." "Asphalt was then so abundant that the Dead Sea was often referred to as Lake Asphaltites." "It was so valuable that it was widely traded and even turned up as far away as Ancient Egypt, where it was used in the mummification process." "These days, asphalt seldom appears." "The last major sighting was in 1969, when a two-metre long slab bobbed to the surface weighing more than a ton." "In Biblical times, a block this size would have been worth a fortune." "So if Sodom and Gomorrah were here, it's highly probable that trading in asphalt would have been a major source of income." "And the best place for enterprising traders to live would have been here, at the water's edge, where it was easier to gather the huge blocks bobbing up to the surface." "And that was the problem, because the land here is susceptible to a process called liquefaction, which is when the ground beneath your feet turns to liquid." "And now, we ARE talking catastrophe." "Now the land down by the shoreline is saturated with water, but it's holding my weight." "But if it gets shaken during an earthquake in the rocks below, then the vibrations cause the sand grains to part, causing water to come to the surface, and turning the ground into liquid." "Well, not much of an earthquake." "But what should happen is the land turns to quicksand." "Well, it's not bad." "Eh?" "Now imagine if there were whole communities here, especially if the houses were built on slopes leading to the shore." "They would have slid into the water and down to the bottom of the sea." "So the geology of the Dead Sea could account for earthquakes and liquefaction." "But what about the final part of the puzzle... ..the fire and brimstone mentioned in the Bible?" "The fault lines which provided the pathways for asphalt might explain this too." "As well as being famous for its salt waters and mineral-rich mud, the Dead Sea offers visitors another treat - bathing in hot natural springs." "And when I say hot, I mean it." "Oh." "Ow!" "Ah!" "It's..." "Ah!" "It's so hot!" "These guys are mad." "This is really hot water that's bubbling up through these cracks." "Deep down, below my feet, there's gas." "It's highly flammable methane." "The seismic activity has created the cracks and the methane gas is rising to the surface." "All it takes is a few bolts of lightning and you've got your fire and brimstone." "Earthquakes, liquefaction, exploding gases..." "A geological explanation for the destruction of Sodom and Gomorrah seems reasonable enough." "But does it really prove that the two cities existed?" "To be honest, we're really not sure." "Probably, the definitive proof only lies out there... in the depths of the Dead Sea." "What we do know is that as well as asphalt, the seismic activity in the region produced something of even greater value, which was to revolutionise the fortunes of those living here." "In 1997, archaeologists working here in southern Jordan made a remarkable discovery." "They uncovered an ancient village that dated back to the early Bronze Age... roughly 5,500 years ago." "At its heart, were the remains of a huge copper factory... the largest ever discovered in the Middle East." "Beneath the rubble were hundreds of copper ingots and casting moulds for tools like chisels and axes." "But why was the factory here at this remote spot?" "The surrounding rocks reveal the answer." "Six hundred million years ago, semi-molten rocks deep beneath my feet heated up water." "As that water travelled up through cracks towards the earth's surface, it gathered up tiny specks of copper from the surrounding rocks." "As it got near the surface, the water cooled and it deposited the copper in the earthquake cracks, forming thick veins of this stuff." "Isn't it brilliant?" "!" "These rocks contain malachite, a copper ore, and the workers would have used furnaces to extract the copper from the rocks." "The vast amount of slag or coal waste found littering the site indicates that the factory must have been producing copper on an industrial scale." "The lives of the inhabitants - who had previously led a nomadic, pastoral life - must have been transformed by this gift from the rocks." "But copper wasn't the only metal released by earthquake activity." "Throughout the Med, man began to exploit a whole range of other minerals, one of which held a deadly secret." "Every year, millions of visitors flock to Rome, attracted by the charms of the Eternal City." "With its vibrant street life, seductive shops, fantastic food and rich cultural history, Italy's capital is a tourist's paradise." "I'd like to see the best of Rome, please." "Among Rome's most popular attractions are its ancient monuments... reminders of its fabled past as the greatest civilisation the world has ever known." "For 500 years, the Romans dominated the Mediterranean and beyond." "At its height, the Empire stretched from Scotland to the African deserts." "But in 476 AD, the Emperor was deposed and the Barbarians took over." "Rome was transformed from a bustling city of millions into a provincial town of a few thousand." "Historians have put forward many reasons for the decline and fall of what was once the most powerful empire in the world." "But as a geologist, I've got a theory that the Empire was brought to its knees by this rock." "Let's see if anyone agrees with my theory." "Excuse me." "Do you speak English?" "Do you speak English?" "What caused the collapse of the Roman Empire?" "Why did it all end?" "Decadence." "Too much excesses." "Oh!" "That sounds good." "How does that kill you?" "You know what that means?" "Yes, I know." "Shall I tell you?" "NO!" "I know what it means." "Shall I say in plain English?" "I wasn't sure..." "Sorry?" "No." "A little bit of English?" "A little bit." "But I..." "No, no, no." "Come back, come back, come back." "No, no, no, no." "I just..." "It's one quick question." "Roman Empire, collapsed." "Why?" "There was a big earthquake." "Big earthquake?" "I think so." "It was the Barbarians." "It was the Germans." "There was a huge hole on the ground and I think just went down and..." "Just collapsed into it?" "Economic collapse." "Emperors enjoying themselves too much, spending too much money." "It's a pretty big empire though." "Yeah." "It was a big earthquake too." "Great." "They tried to conquer Britain, but they ran out of legions." "That was ages before it actually collapsed." "It was like a storm or an earthquake?" "I think so." "Wow." "Like many put together..." "Yeah, yeah." "And it just all..." "All of it." "That's interesting." "That's what I'm looking for - geology reasons." "OK, thank you very much." "Thanks." "Bye." "Bye." "Time to ask a genuine Roman." "You're the perfect man." "I'm trying to find out what caused the collapse of the Roman Empire." "Romano." "Romano." "Romano." "Yes." "Collapse." "Roma." "Collapso." "Collapso Roman Empire." "Per que?" "Per que?" "Per que collapso?" "HE SPEAKS IN ITALIAN" "Oh." "I don't know." "What, this?" "Some interesting answers, but none of them came up with what I think might be a major culprit." "This rock is called lead sulphide and it's the source of one of the most toxic of all metals - lead." "If lead gets into your body, it can cause sterility in men and infertility in women." "It can also cause an increased likelihood of stillbirth and miscarriage." "And when it gets to your brain, it can cause major neurological damage, including imbecility, hyperactivity and senility." "The trouble is, the Romans were infatuated with it." "Lead was fantastically useful in Imperial Rome." "It was readily available, inexpensive, easy to mine, smelt and work, and very resistant to corrosion." "So when the Romans built their lavish public and private baths, lead was the metal of choice for the miles of water piping." "Now with all that lead plumbing in public baths, wouldn't the Roman bathers have been at risk?" "But there's no evidence that bathing in lead-contaminated water is dangerous." "So what about drinking it?" "Rome today is dotted with water fountains... over 3,500 of them." "And in ancient Rome, it was no different." "The water would have travelled along lead pipes, so it's reasonable to assume that if you drank it regularly, you would have exposed yourself to lead poisoning." "A neat theory but one not supported by geology." "Much of the water which supplied Rome was sourced from springs in the countryside, as much as 80 kilometres away." "To bring the water into the city, Roman engineers built these magnificent aqueducts." "The spring water came up through the limestone, so it was high in calcium." "This created limescale... the same stuff that furs up kettles and which acted as a protective coating on the inside of the lead pipes." "And another protective factor was the sheer abundance of water in Rome." "The Romans didn't have much use for taps." "Piped water would gush into fountains and basins, and then overflow into the gutters and with typical Roman efficiency, flush out the sewers." "So if water didn't lead to lead poisoning, what did?" "The relentless pursuit of la dolce vita - the good life." "The Italians' passionate enthusiasm for the good things in life is legendary." "Here in Rome, the sense of chic is everywhere." "And few things are more important to the Italians than eating well." "Five different types of tomato." "Do you eat these?" "Si, mangiare." "The flowers." "What's this?" "Trippa." "Tripe." "Stomach?" "Oh, gosh!" "I didn't really like figs but this is beautiful." "Multi grazie." "Ciao." "Thank you." "But in Imperial Rome, the desire for fine food went way beyond normal appetite." "Upper-class Romans loved their food and drink to such an extent that they became notorious for gluttony and drunkenness." "And this is where the lead poisoning argument really begins to take hold." "The ruling classes drank hugely - anything from one-and-a-half to five litres of wine a day." "What's more, the wine was likely to be contaminated by a deadly additive." "To enhance the colour, sweetness and bouquet of wine as well as to stop it turning sour, winemakers adulterated it with a sweet, aromatic syrup called sapa." "Now sapa is just unfermented grape juice boiled down into a concentrate." "But the problem was that the pots the winemakers used to boil the juice in were made of lead." "Grape juice is very acidic and the acid dissolves lead." "So the syrup or sapa had a very high lead content." "And that is how lead got into wine, with deadly consequences for our wine-guzzling Romans." "As well as poisoning themselves with their excessive drinking, the Roman aristos' love of fine food was also getting them into trouble." "The deadly additive sapa wasn't just used in wine." "It played a major role in the kitchen as a sweetener in sauces and seasonings." "Ciao, Luigi." "How are you?" "I am fine." "You?" "Great." "You've got a steak, so we're ready to roll." "It says that we need pepper." "Yes." "I've asked top chef Luigi Bergeretto to recreate one of the most popular dishes in Ancient Rome, using the original recipe." "There you go." "That's beautiful." "He's going to cook me a beefsteak in a succulent sweet and sour sauce." "Raisins...which I see there." "Honey." "The ingredients are surprisingly familiar." "But I'm going to draw the line at total authenticity." "There's two other ingredients in here causing a bit of concern." "One of them is wine, which we know was contaminated with lead in Roman times." "Have we got some wine?" "Got some wine here." "Is there lead in this?" "No, is lead-free." "Is lead-free, is it?" "Because I know that the Romans used to have tons of lead in their wine, so I was a bit worried." "Not now." "The other thing is this reduced must, which is that deadly grape juice cooked up in the lead pots." "Sapa?" "This is sapa?" "Yes, this is sapa." "And still is used in Sardinia." "Sardinia?" "But was that cooked with lead pots?" "No." "Not now." "So I'm not going to get lead poisoning." "No, no." "Excellent." "Have you cooked it before?" "Not this recipe, really." "OK." "I believe that I can do it because I'm Roman as well, so I know the feeling of the ancient Romans." "The deadly sapa featured in many recipes, and lead would also have been present in cups and plates, as well as pots and pans." "Lead was even in cosmetics." "Fashionable Roman women were into the "white" look so they put powdered white lead on their faces." "Ah!" "Look at this." "Let's see what it's like." "That looks fantastic." "Mmm." "That is beautiful!" "That's never 2,000-year-old meat." "With wine and food and even make-up, lead was everywhere in Ancient Rome." "It's reckoned that an upper-class Roman absorbed about 20 milligrams of lead per day." "More than enough to give anyone chronic lead poisoning within weeks." "In 1st-century Rome, there were already ominous warning signs." "The Roman upper classes were failing to reproduce." "Each generation would be perhaps a quarter of the previous one." "It got so serious that they brought in special laws to grant privileges to fathers with three or more children, and to penalise childless aristocrats." "Sterility and infertility can both be symptoms of lead poisoning, and lead might also explain the bizarre behaviour of some of the emperors." "For instance, it's rumoured Claudius was a mentally unbalanced glutton who was constantly slobbering and shaking." "Caligula was a chronic alcoholic who married his sister, made his horse a consul, turned his palace into a brothel and killed innocent citizens on a whim." "But the most feared for his eccentricities and fits of violence was him..." "Nero - a psychotic monster who poisoned his brother and murdered his mum." "With a series of deranged emperors and a severe breeding crisis among the aristocracy," "I reckon there's enough evidence to suggest that lead definitely played a part in the decline of the greatest civilization the world has ever known." "In my geological tour of the Med, the rocks have provided answers to some tantalising questions." "But there's one final mystery I want to solve." "As before, it revolves around materials coming to the surface via cracks in the ground." "But this time, we're talking about something far more terrifying than lead." "It's when molten rock itself - the magma - breaks through the earth's crust." "It's the stuff of Hollywood disaster movies." "This is the Greek island of Santorini in the Southern Aegean, one of the most turbulent regions on earth." "Santorini, and its smaller neighbours, are all that remains of what was once one large island." "4,000 years ago, it had its heart ripped out by a devastating volcanic eruption." "A massive chunk of the island collapsed beneath the waves, creating a deep crater which the sea rushed in to fill." "The legacy of this catastrophe is a spectacular landscape, which has made Santorini the most popular of all the Greek islands." "But I'm not here for volcanic beaches or beautiful sunsets." "I'm on a quest for the answers to the baffling mystery which the eruption also left behind." "And once again, the answer lies in the rocks." "We all know the story of Pompeii in Italy, buried under a thick layer of volcanic ash when Mount Vesuvius erupted, entombing its inhabitants before they could flee." "Well, here in Santorini, the town of Akrotiri in the south of the island was, just like Pompeii, buried in ash and preserved for posterity." "When archaeologists unearthed Akrotiri from its 10-metre thick blanket of ash, they discovered a time capsule of a lost world." "But astonishingly, unlike Pompeii, there were no bodies buried beneath the rubble." "So how did its inhabitants manage to escape before the eruption?" "They were saved by the rocks - the very ones that fell on them." "And these are the rocks that did it." "The story begins with the formation of islands like Santorini about one-and-a-half million years ago." "Back then, the geological processes in the Mediterranean were much the same as they are today." "The African plate was moving Northwest, at a speed of about four to five centimetres a year, and it was sinking underneath the Aegean plate." "This had been going on for about 15 million years, pushing the tip of the African plate down to a depth of 130 kilometres." "Down at that depth, the heat and pressure are enough to generate molten rock." "Because the Mediterranean is an earthquake zone, there are plenty of faults for the red hot magma to use as pathways to the surface." "When it got there, one-and-a-half million years ago, it created volcanoes like Santorini." "At the time of the eruption in 1628BC," "Santorini was a flourishing trading post for the Minoans - a cultured Greek-speaking people whose main base was the island of Crete 100km to the south." "The excavations at Akrotiri reveal a highly sophisticated society, living in three-storey houses, fitted with plumbing and decorated with murals and frescoes." "Many of the rooms showed signs of earthquake damage, a warning that a major volcanic eruption might be imminent." "But it was clear that the people of Akrotiri had ignored these signs and stayed on to rebuild their damaged city." "Pots of plaster and paint lay abandoned in the partly decorated rooms." "So if the eruption came as a surprise, what explains the absence of bodies?" "The answer lies, once again, in the rocks." "This... is soil from an ancient land surface that the people of Akrotiri lived on before the eruption." "And this...is a layer of rock that was blasted out at the start of the eruption 3,500 years ago." "It's made... ..of pumice, which is formed by molten lava that's full of trapped air bubbles." "And that gives it all these holes." "That makes it incredibly light." "Now the first pumice to be thrown out by the eruption was this yellow band here." "The colour is really significant because it tells us that the rock is oxidised." "In other words, the pumice had lain on the land surface, unburied and exposed to the atmosphere for at least a few weeks." "Time enough to give warning to the people of Akrotiri." "This light showering of pumice was a heck of a wake-up call." "Thanks to this early warning, the villagers escaped before the final deadly blast." "This would explain the absence of objects of value in the ruins of Akrotiri." "The fleeing townsfolk took their most prized possessions with them." "A couple of months after this first thin scattering of pumice, the volcano erupted out the really nasty stuff." "Within a matter of hours, this three-metre thick layer of pumice had rained down." "Over the next four days, this 50-metre thick blanket of ash and pumice covered the whole island." "In the best Hollywood disaster films, just when you think it's safe to get back in the water, there's some terrifying twist." "Well, the exact same thing happened here." "The volcano had a deadly trick up its sleeve." "When the volcano erupted, the outpouring of magma created an enormous chamber deep in the rocks which couldn't hold the weight of the island." "The chamber collapsed and the centre of the volcano sank beneath the waves with a crash probably heard throughout the Aegean." "Across the Aegean in Crete, the Minoans escaped the immediate effects of the blast." "But some scholars believe that they were the victims of its deadly aftermath." "The collapse of the volcano probably caused a violent sea wave or tsunami." "They travel at up to 800 kilometres an hour, and when they hit shallow coastal waters, they rise up into huge walls of water, up to 30 metres high." "The tsunami would have pounded across into Crete, causing widespread flooding and devastation." "Within just a few decades, the Minoan civilisation had gone into terminal decline." "Did the volcanic catastrophe here on Santorini deliver a death blow to the Minoans?" "It's a fascinating whodunnit and the jury is still out." "Santorini is a living, breathing volcano." "Just under 300 years ago - a blink of an eye in geological time - eruptions caused the sea floor to rise to the surface and form a new island in the crater." "It's known as Nea Kameni " "New Burnt Island." "Its most recent eruption was in 1950, so it hasn't finished yet." "It all looks so tranquil now, but this is the centre of the blast that ripped apart the island of Santorini 3,500 years ago." "But all this lava is modern, created in the last 200 years." "Thank you." "It just goes up, does it?" "Oh, right." "I should be able to do that." "Excellent, see you later." "Bye bye." "Look at this." ""Keep the volcano clean." OK." "As I said at the beginning, we take our Mediterranean holidays in some of the most dangerous places on earth." "Are we mad?" "Hi." "Is it far?" "Yes." "No?" "Very far." "Is it worth..." "Is it good?" "Yes, perfect." "Are you not a bit worried that it's... this is a volcano?" "It is, yes." "You're walking on a volcano." "Want to see it." "You're crazy." "I'm glad you're not worried." "Now, what do you want to hear?" "No, of course not." "No, I just..." "I just like to see if people are having fun on volcanoes." "See you." "Bye." "Thanks." "Hi there." "Are you not worried about this, being on a volcano?" "No." "It won't...eruption." "But over there, there's some steam coming out." "Yeah, we saw that from distant." "You don't think there's a risk here?" "No." "So no-one's worried that you're standing on a volcano?" "It's more dangerous coming down that road in the bus." "You don't feel you're taking a risk trundling up here and..." "No." "They didn't get us to sign anything saying we're in danger." "I reckon they know." "Do you like taking risks?" "Sure." "Do you think this is taking a risk?" "No." "No." "So how far in your risk table of one to ten is walking up an active volcano and standing in the crater?" "Er, two." "Two?" "!" "Two." "And what is at three then?" "What's more risky?" "A bubbly volcano, I guess." "That's probably true." "Right, thanks then." "Thanks." "Bye." "Everyone feels happy on a volcano." "Must be the fumes." "The truth is, if and when this volcano starts to erupt again, we'll probably know about it." "The stinking gases will get worse, the land will start to rise and earthquakes will begin to pop off." "The same warning signals that alerted the locals 3,500 years ago." "But until then, visitors will continue to flock to Santorini and its infant volcano, despite the knowledge that they're flirting with danger." "In my tour of the Med, I've seen how cracks in the earth have blessed the region with mineral wealth, but cursed it with natural disasters." "But these cracks have also offered solutions to some baffling mysteries." "Later in this series, I'll show you other ways in which geology has influenced the civilisations of the Med." "I'll reveal how rocks were behind the reason the Egyptians built triangles, the Greeks - squares and the Romans - perfect circles." "I'll look at how art through the ages owes its colours to the rocks, from the paintings of our Stone Age ancestors to the Impressionists and beyond." "And I'll be looking at salt." "You may see it as something you just stick on your fish and chips..." "Delicious. ..but to me as a geologist, it means war, death and the end of the world as we know it." "It's not all depressing though." "Don't forget there's also a good side to rocks." "For further information on Open University programmes, please go to open2.net" "E-mail us at subtitling@bbc.co.uk" "Every year thousands of us flock to the Mediterranean." "It's one of the most popular holiday destinations in the world." "And it's packed full of the most beautiful ancient sites." "But these buildings hold secrets that you'll never read about in the guidebooks." "'With the help of a few handy props... '..and some unsuspecting holidaymakers...'" "What are you doing?" "You're not connected to anything now." "'.." "I'm going to unlock the mysteries of these ancient monuments.'" "How come the Egyptians made giant triangles?" "But the Greeks preferred rectangles?" "And the Romans built the ultimate circle?" "As a geologist, I believe the history of civilisation was driven by rocks." "And I'm going to see how the styles and shapes of the Med's famous ancient buildings were actually determined by the rocks the different civilisations had right on their doorstep." "The first stop on my geological tour is Cairo, in Egypt." "As holiday destinations go, it's hot, it's dusty... and it's pretty chaotic." "Cairo certainly supplies an exhilarating feast for all the senses." "As well as the giant medieval mosques, right at the heart of the city are the bustling bazaars." "Do I look silly?" "Do I?" "Yeah?" "There's also opportunity to try out some local pastimes." "Strangest bagpipe I've ever tried." "But away from the "hubble-bubble" of modern Egypt, most visitors come here to feast their eyes on what the ancient Egyptians left behind." "And there's one site in particular I've got in mind." "What we all come to see is the last remaining wonder of the Seven Great Wonders of the Ancient World." "Just 30 minutes' drive out of central Cairo stands the most famous architectural legacy of the ancient Egyptian civilisation." "It can be a bit of a white-knuckle ride getting there..." "..but if you do survive the taxi journey, the sight is truly awesome." "These are the famous pyramids of Giza, dating from the 4th Dynasty." "The largest is the Great Pyramid, standing over 130m tall, built by Pharaoh Khufu, also known as Cheops, and finished around 2530BC." "The pyramid of his son Khafre, who also went by the name of Chephren, is a tad smaller and finished 30 years later." "While the smallest of the three main pyramids is that of Menkaure, completed around 2470BC." "Knowing who built what and when is all well and good, but to be honest, I find all these names and dates a bit confusing." "Besides, from my geological perspective, the tour guides miss out the most interesting stuff - the rocks." "The rock in the pyramid, how it was formed?" "I don't know." "The gentlemen - he know everything." "Perhaps we know in Russian, but not in English." "Do you speak English?" "A little?" "No, nothing?" "Oh, dear." "I'm wanting to know where the rock in the pyramids has come from." "They're very good pyramids." "They all think I'm completely mad." "No-one knows anything about rocks." "It's very disappointing." "Honestly, I don't know." "I don't know." "HE CONVERSES IN ARABIC" "Help!" "WOMAN ON CAMEL:" "How did the rock form?" "!" "I don't know." "You tell us!" "These great big blocks of rock weren't always as inanimate as they are now." "Neither were they as dry and dusty." "They actually started off life as living, breathing creatures swimming around in the ocean." "I'm going on a geological excursion, back in time, to find out just how animals got turned into solid rock." "Imagine I've travelled back to the Eocene era, 50 million years ago." "Yes, I know there weren't boats then, but bear with me here." "It was an age when the dinosaurs had become extinct, and this part of the world was much wetter than it is today." "Modern-day Egypt was actually submerged under water, covered by an ocean called the Tethys." "The Tethys ocean was huge, more than five times bigger than today's Mediterranean, and stretched from the Alps to the Himalayas... although of course they weren't there yet." "But beyond its size the Tethys ocean floor was a giant rock factory, providing material to build some of Egypt's greatest monuments." "The raw material for this subaquatic rock factory was the marine wildlife." "The Tethys was teeming with creatures, whose descendants still live in the oceans today." "But only certain types of sea life would eventually help create the rock used in the pyramids." "The geologically important animals were the ones without a backbone... the invertebrates, clams, corals, snails, but mainly billions of tonnes of microscopic plankton." "Although spineless, plankton and the other marine invertebrates, have hard body parts, which contain a substance called calcium carbonate." "This was the key ingredient to making the rock." "When the animals died, their flesh would have decayed or been eaten, leaving the hard calcified bits to come to rest on the ocean floor." "Over millions of years, tonnes and tonnes of the dead animal body parts would have accumulated on the seabed." "Think of it as like making a geological sandwich, but these leftovers would be lifeless animals." "No, I don't want that." "I want some of that!" "I want..." "Yeah, yeah, thanks!" "Right, right, right!" "Oh, I don't want that." "That looks disgusting." "Right." "Now slowly but surely, the layers of dead animals would have got squashed and compacted together, not by some giant arm, but by the weight of the new dead creatures that were being continually deposited on top." "Because the dead sea life was laid down as fragments or sediment, this stone sandwich, which formed over million years, is called sedimentary rock." "What were once living sea creatures had been transformed into a type of sedimentary rock called limestone." "If you look carefully, you can often still see the animal remains in the rock." "But creating a heap of limestone underneath the ocean floor wasn't much use as a building material, unless you were a fish with planning permission." "But fortunately, the ancient Egyptians wouldn't need to go to the rock, because the rock would come to them, as nothing in geology stays still for very long." "Over time, one of the most important driving forces of nature brought the limestone up from below the sea floor, direct to the early builders." "Think of this egg as the world." "The shell is the Earth's crust, but it's not solid." "It's broken up into a number of pieces called tectonic plates." "This one is the African plate, and it's moving northwards into the European one." "As part of this massive continental movement, sections of the Tethys ocean floor were physically pushed up from the watery depths." "What was the seabed had emerged from the water to become the bedrock of northern Egypt." "Here in Giza, it was that same limestone rock upon which Pharaoh decided to build his pyramid." "It's thought that these behemoths were built to act as eternal resting places... homes for the king's earthly remains once they'd passed on, into the afterlife." "Obsessed with what lay beyond death," "Pharaoh believed, that to guarantee the immortality of his soul, his body had to be preserved for eternity." "Pharaoh also believed his body should be very close to the stars and the sun." "To provide his soul easy access to the heavens, his burial house had to be as tall as possible." "From my geological point of view, there's actually a more practical explanation as to why the Egyptians built giant pyramids." "First off, to stand any chance of lasting for all eternity, the obvious thing to do was to build the mausoleum out of rock." "Thanks to geology, there was a shedload of limestone right on Pharaoh's doorstep." "But his builders were doubly lucky." "Their limestone came in preformed ready-made chunks, naturally cracked as a result of the massive geological collision between Africa and Europe." "Imagine this chocolate bar is a layer of limestone on the African plate." "As a result of the collision, the African plate is getting pushed down under the European one." "Now, if I press down on this, you can see a series of cracks appear." "That's because the downward pressure of my fingers is sending energy through the bar, forming the cracks." "These are the Mokattam hills, overlooking Cairo, where much of the rock for the pyramids was quarried." "Here, the limestone was cracked in two directions, naturally forming large square blocks, which were then cut out and used to build with." "So Pharaoh had loads of rock for his mausoleum, but to be close to the heavens, he needed a really tall building... and I mean gigantic." "To build the Great Pyramid, this one here, took nearly two and a half million giant blocks, each one weighing well over two tonnes." "The manpower needed must have been phenomenal." "But fortunately, geology once again came to the rescue... in the shape of the River Nile." "The Nile is the longest river in the world, and is the lifeblood of Egypt." "Without it, Egyptian civilisation as we know it just wouldn't exist." "The river begins life over 3,500 kilometres away, in the mountains of East Africa." "Conveniently for the Egyptians, the Nile drains all the way to the Mediterranean, straight through their country." "During the time of the Pharaohs, every year for three months, heavy rains in the heart of Africa would cause the Nile to flood here in Egypt." "Flooding may not sound like a good thing, but it was essential to revitalise the farmland either side of the river, bathing it in rich fertile soils." "Yet for the duration of the flood, the thousands of farmers had very little to do." "So Pharaoh killed two birds with one stone." "The potentially restless workers needed to be kept occupied, and with summer holidays yet to be invented," "Pharaoh had an ideal project to keep them busy." "Building a pyramid." "It's thought that over 20,000 men worked in three-month shifts, labouring for over 20 years just to build the Great Pyramid alone." "But of all the shapes Pharaoh could have chosen for his everlasting mausoleum, why pick a pyramid?" "If you want to make a pile of rocks as tall as possible, there's one particular shape that will allow you to do this, much better than any other." "Whether the Egyptians realised it or not, it's no coincidence that pyramids mimic another naturally occurring shape." "Mountains." "Mountains and pyramids have to act against gravity and hold up their own weight." "And the shape of a pyramid is a really effective way of spreading the load." "The few stones at the top only have to support their own weight." "But lower down where the weight is much greater, there's more blocks to share the load." "The pyramid builders took advantage of the rock's natural strength, which was rooted in the way it was originally formed by compression beneath the Tethys ocean." "Put limestone blocks under pressure by stacking them on top of each other, and they should remain strong for what could be an eternity." "It's like sitting on a big tea cosy!" "Wahey!" "Whoa!" "I'm not denying that the pyramids are an amazing achievement." "But, if I was being picky, there's just one major drawback." "They made a monstrously huge building, but the space inside is about the size of that tour bus." "I suppose a compact, cosy, easy to maintain space is fine... ..if you're dead." "But the ancient Egyptians also wanted magnificent buildings where their gods could be worshipped, by the living." "They wanted to build not a triangular tomb, but a temple with a roof." "For that, we need to head south." "Onward!" "As Egyptian temples go, you don't get much better than this... the Temple of Amun at Karnak in Luxor." "It's a wonder of architectural creativity, yet these buildings look the way they do, because of the rocks." "Founded around 2000BC by Pharaoh Senwosret the 1st, it covers an enormous 100 hectares and is the largest of the Egyptian temples." "Pretty impressive when you consider it's just a giant sandcastle." "When the Egyptians built this place, they were again constrained by the rocks that geology had provided them." "As with the pyramids, the builders here turned to their local stone, but it wasn't the same as that found up north." "It's less than a day's drive south of the pyramids, but here the Egyptians used a different kind of sedimentary rock, called sandstone." "Remember Egypt was originally under the Tethys ocean." "What would eventually become Luxor was actually quite close to the ancient shoreline." "Over millions of years, prehistoric rivers would have washed huge quantities of sand into the ocean." "This then got compacted over time to form sandstone." "Like other types of sedimentary rock, sandstone was a very good building material." "Imagine these wafers are layers of sandstone." "Just like the limestone used in the pyramids, you stack them up, push down, and it's very strong." "Ideal for building giant walls." "But the Egyptians still had to work out how to build and support a roof." "They discovered that sedimentary rock, whether it was the sandstone here, or the limestone in the pyramids, had two major architectural flaws." "To support a large roof, you're going to need some sort of columns." "To make columns from sandstone, the obvious thing to do would be to dig out long horizontal lengths, turn them 90 degrees and stand them upright." "But look what happens... ..the layers just break apart." "Sedimentary rock is only really strong when put under pressure, with its internal layers being pushed together in compression, just like when the rock was first formed." "So the temple builders cheated." "This cavernous room in the centre of the temple is known as the Great Hypostyle Hall." "To make these giant columns, first the Egyptians cut the sandstone into small blocks with rounded-off edges." "Then, by stacking the blocks on top of each other, in layers, they kept the rock in compression, yet were able to create very tall, round columns." "The Egyptians had got the support structures they needed." "Now they wanted a magnificent stone roof." "And this meant overcoming another problem." "A sandstone roof slab is only strong when under compression." "Which was fine at either end, where it was held up by columns." "But the unsupported bit in the middle would be under a different force called tension." "This posed a dilemma." "Put the columns too far apart, and the roof stone would collapse." "To get round this problem, and yet still hold up a stone roof that originally stretched across the entire hall, the builders virtually filled the room with over 130 giant columns." "The guidebooks might tell you that this hall of columns was deliberately created by the ancients to resemble a swamp of papyrus." "However, as a geologist, I see it a different way." "Because they were restricted by the properties of the rocks to hand, this was the only way they could support such a large stone roof." "It's an amazing sight, but it does look a little bit like a store room for columns." "With their desire to create large, awe-inspiring temples, the Egyptians established the skills to actually shape rock... into columns..." "..and crossbeams... otherwise known as posts and lintels." "This became the fundamental way to support large heavy roofs." "In the geological lottery of the Med, the hand the Egyptians were dealt dictated the grand designs they used." "And their techniques had not gone unnoticed." "We obviously weren't the first to see this monumental stone architecture." "Some of the earliest visitors were the ancient Greeks and what they took back home was much more than just memories." "What they learned from the Egyptian stonemasons would inspire them to go one better." "Greece is a major tourist destination in the Med." "Although many of us skip off to the islands, the capital," "Athens, is the place to see the defining style of ancient Greek architecture." "Over a thousand years after Karnak was built, the Greeks were a civilisation on the up." "They wanted to go large - building impressive monumental structures." "But like the Egyptians before them, they still had to build using materials they had to hand." "With a wetter climate, up on the hills grew vast forests." "And before the 6th century BC, the Greeks used wood to hold up their temple roofs." "Although plentiful, wood was vulnerable to fire and decay, and its limited strength restricted the size and scale of the roofs it could support." "Which was why the Greeks were so excited when travellers returning from Egypt brought with them the expertise to carve round stone columns." "Told you rocks were important." "The Greeks quickly put their new skills into practice, replacing the wooden columns with carved stone ones." "The thing was, geology had dealt the Greeks a slightly different hand." "In addition to limestone, which was still available, the Greeks had something very special on their doorstep the Egyptians just didn't have." "A rock called marble." "This rock completely seduced the ancient Greeks." "Once they got their hands on it, nothing else would do." "It was marble that put ancient Greece on the architectural map." "What is marble?" "A stone." "Yeah, what..." "How did the Earth form it?" "OK..." "Uncle John." "I'd say very carefully because it's very pretty." "Cos you look at..." "We love your accent." "..Thank you very much." "You've got the wrong couple here." "I've got to say, mate." "Marble is like the coolest stone to me." "It seems like it lasts forever." "It's so beautiful." "I don't smoke." "You don't smoke?" "No." "Marble...not Marlboro." "Not Marlboro." "Whatever the chemical reaction or whatever it is called..." "Haven'tyougotaneasier question?" "That was my easiest." "Marble actually started out life as limestone, but something happened millions of years ago to transform it from one type of rock to the other." "Ah!" "Efharisto." "This cake with its nice horizontal layers looks like limestone." "Whereas this cake is completely different." "The layers have been squished and crumpled to produce a swirl pattern, which is exactly like marble." "To see how you turn limestone into marble, I need to go back in time." "I'm going back 190 million years, to the Jurassic era." "A time when the Greek marble first started to form." "This may look like a typical hotel pool, but it's exactly what I need to explain how geology provided the driving force to turn limestone into marble." "For this demonstration, I'm going to have to get wet again." "And I'll need some props." "Remember the Earth's crust is broken into pieces called tectonic plates." "Imagine this red airbed is the African one and this blue airbed is the European one." "Now, the plates move around on the Earth's mantle and these two are on a collision course." "The African plate was heading northwards, moving towards Europe." "As a result, there was an enormous collision and this squashed the limestone." "But there was more geological action to come." "Because Africa's heavier, it gets pushed down underneath the lighter European plate, forming what's called a subduction zone." "Within this zone, some of the squashed limestone rock was pushed down into the Earth, where it went through further transformation." "Although it was the movement of the tectonic plates that provided the driving force needed to convert limestone into marble, it's what happened to the microscopic particles within the rock that makes marble so unique." "To show you what I mean, I've rounded up some volunteers down on the beach, who will make great rock particles." "With the wind picking up, there's not much else to do today." "OK, I'd like you to get towels down." "So if you could just find a spot and I'll tweak a few of you left and right." "Just find a spot." "Don't be shy." "This is the nicest looking limestone I've ever seen." "Let me give you a hand." "And there's a space here." "You happy over there?" "OK, you're looking fantastic." "I'm off to look at you from up here." "Oh, nice limestone." "I've arranged my volunteers to look like particles of sedimentary rock." "They're all making the most of the available space." "During the collision of the tectonic plates, that space got smaller." "I'm going to see what happens if I do the same to those holiday-makers." "OK, I just need you all to squeeze together a little bit." "Shift up a little bit." "As close as you..." "That's perfect." "We're gonna get cosy." "Squeeze up to fill those gaps." "How we doing here?" "Push, push." "Squeeze." "Squeeze." "Let's get much closer, actually, let's squash." "Shift up." "Shift." "Like the particles in sedimentary rock, my holiday-makers have been squeezed into a much smaller space, all packed close together." "But we're only halfway towards marble." "As well as the pressure, it's starting to get hot." "When the African plate was forced underneath the European one, the rock was taken down, closer to the Earth's hot interior, where it got heated." "This caused the rock particles to fuse and interlock." "I'm going to get my volunteers to do the same." "Now what I want you to do is to take your right hand, put it on the right shoulder of the person beside you, and take your left leg and touch the person on your right with it." "Erm... that's fine." "Your right arm onto there." "Actually, it looks quite disgusting to be honest." "What are you doing?" "You're not connected to anything now!" "There!" "There to there!" "The high temperature and pressure caused the rock particles to grow and form new crystals, interlocking the particles and fusing the whole mass together." "So given time, pressure and heat, sedimentary rock was transformed into something called metamorphic rock, the most important of which to the Greeks, was marble." "Metamorphic rock comes in many forms, not just marble, and all have been physically altered by heat and pressure inside the Earth's crust." "Although the Greek marble was created beneath the ocean, movement of the tectonic plates around 12 million years ago pushed it up from the depths... finally to see the light of day." "As luck would have it, nature provided the Greeks with an enormous hill of quality marble." "This is Mount Pentelikon, a stone's throw from the capital, Athens." "Everywhere you look around here... ..is marble." "This rock face was one of the actual sites where the ancient Greeks used to quarry the very pure white marble." "And it was this that they used to create some of their most famous buildings." "And look over here." "They even had a marble-paved road to take the rock straight down into town." "Using their own local marble, plus Egyptian stone-working techniques, the Athenians went to town." "I've come to the famous Acropolis that stands sentinel over Athens." "It's one of the most important ancient sites in the Western world, and there's no escaping it... it's wall-to-wall marble." "Perched on top of this rocky outcrop is a monument which, more than any other, epitomises the glory of ancient Greece." "The jewel in the crown of the Acropolis is the Parthenon." "It's the largest of the Greek mainland temples and it's the only one built completely out of Pentelic marble." "It's dedicated to the patron of Athens, the goddess Athena, and it took nine years to build." "Completed in 438BC, the Parthenon stands 24 metres tall and is over 70 metres long." "To keep the patron goddess happy, whose giant statue was housed here, the temple had to be very grand and made of the finest quality stone." "In its time, the Parthenon would have been a dazzling edifice in glowing white marble." "It's nowhere near the scale of Karnak and other Egyptian temples, but thanks to marble, the Parthenon is a much more elegant, more sophisticated looking building." "There was originally 46 impressive marble columns surrounding the inner sanctum." "And those columns were far more slender than anything created by the Egyptians using sandstone." "But the slimming-down of columns didn't stop there." "Standing right next to the Parthenon is another testament to the glory of marble." "This rather slinky looking temple is called the Erechtheum, dedicated to the gods Athena and Poseidon." "Here, marble was used to make even thinner, more ornate pillars." "A design that would become a mainstay of Greek architecture." "The secret of marble's success lies in the process that created it." "Its fused crystalline structure made it really strong and the columns could hold significantly more weight than if they were made of sedimentary rock." "The marble crossbeams, or lintels, could stretch across wider gaps, without risk of cracking in the middle." "This allowed the Greeks to open out their architecture, producing a greater feeling of space." "Marble's special properties also made it ideal for carving, with the Greek craftsmen sculpting highly ornate statues, bearing ultra-realistic features." "Marble may have started out as an alternative building material to wood, but the Greeks took it and turned it into an architectural art form, leaving behind the ultimate rectangular temple." "But there was another ancient civilisation just round the block who'd discover that they'd really hit the geological jackpot." "And what they did changed the shape of architecture forever." "I'm off west... to Italy... to catch up with the Romans." "I've come straight to the heart of the ancient Roman Empire, to the city of Rome." "I'm here to see how geology dealt the Roman builders the best hand of all." "Founded in 753BC on the banks of the River Tiber," "Rome has a perfect mix of antiquity, and urban chic." "Although the empire eventually collapsed, there's still a lot of Ancient Rome to see today, with many impressive buildings standing firm." "At first glance, it looks like most of the ancient Roman buildings were made of brick." "This feast of bricks is Trajan's Market, built, unsurprisingly, during the reign of Emperor Trajan around AD 114." "The bricks used to build this ancient department store were made using mud and clay dug from the riverbanks along the Tiber Valley." "But the ever-practical Romans thought up an ingenious strategy to make the bricks very hardwearing." "Using wood-fired kilns to bake their skinny mud bricks, the Romans had created an incredibly strong and very durable material to build with." "But the mud they used to make these bricks is not the geological jackpot I'm talking about." "Where the Egyptians had sedimentary rock, and the Greeks had their metamorphic marble, the Romans had something far more potent." "It's what's behind these bricks that was the key to the creation of some of their most spectacular buildings." "What geological process do you think formed the rocks that Rome was built on?" "That built all these fantastic monuments?" "That's a little too complicated there." "They dug it up from quarries." "But where did they get the stone originally from?" "Where did the stone come from?" "Quarries." "Before quarries." "Near..." "Oh." "Well, places like caves and seas." "It's a big scientific process." "Who knows?" "What gave the Romans all these rocks?" "What?" "The answer isn't immediately obvious, as the Romans discovered their geological bonanza in one of the most unlikely places." "If you were looking for a place in the sun," "I'm not sure "volcano" would be high on your list of must-have local amenities." "We tend to think of volcanoes as one of the most destructive geological forces known to man, destroying buildings, cities, even civilisations, rather than helping to create them." "You wouldn't know it for all this cloud, but I'm on the top of Mount Vesuvius, which overlooks the Bay of Naples... somewhere over there." "Now although it's an active volcano, at the moment, thankfully, there's nothing to report." "But in 79AD, there was a massive eruption - it devastated the whole region." "Less than 15 kilometres from here are the remains of two of its most famous casualties," "Herculaneum and Pompeii." "When Vesuvius went up, thousands of people were killed within minutes, their flesh vaporised by the intense heat of the eruption." "Casts of fallen bodies lie frozen in time, where they fell." "For thousands of years before Pompeii perished, volcanoes of this region had been erupting." "And as part and parcel of their destructive nature, they produced all sorts of rocky material." "And one of these would be the magical raw ingredient that ultimately would change the way the Romans built forever." "But why volcanoes occurred in Italy in the first place is once again down to a chain of geological events." "To show you how they came about," "I don't need to go too far back in time." "It's a journey to the Miocene era, just ten million years ago." "Remember the tectonic plates?" "The African one had collided with the European one and was being pushed down into the Earth." "Well, beyond a certain depth, the heat was so intense that the rock actually melted to form magma." "Magma is the name given to hot molten rock that naturally exists deep beneath the Earth's surface." "Imagine this piazza is a cross section looking down through the Earth below Italy roughly ten million years ago." "The bollards on the far left represent the surface of the Earth." "The area on the right near the road mark a point about 100 kilometres below the Earth's surface where the rock had melted to form magma." "Now, to find out what happened to that newly formed magma," "I need to round up a few little helpers." "OK, who wants to look a bit silly?" "Let's put..." "Can you put these on?" "'This school group has volunteered to behave like molten magma for the afternoon.'" "Anyone feeling silly?" "ALL:" "Yeah." "I agree." "Have you guys shrunk, or are these big?" "OK, who needs balloons?" "'The red balloons are to show that the magma was very hot." "'Here, at 100 kilometres below the Earth's surface, 'it would have been around an incredible 1,000 Celsius.'" "All right, we'll get you set." "There's another one." "OK, I think we're ready." "Andiamo." "This way, I think." "Are we all going?" "Good." "The hot molten magma was actually very buoyant, and just like my mini tour group following me across the square, the magma started to rise up from the depths where it was created, heading towards the Earth's surface." "It would have had to push and squeeze its way up through small cracks in the surrounding solid rock." "So, the magma's progress on the way up was very slow." "It was forced to deviate all over the shop, and the longer its journey took, the colder it got." "I think we'll just sit down." "'Eventually the magma's progress stopped altogether, way below the Earth's surface.'" "My magma tour group has now lost so much heat that they have actually solidified into something called igneous rock." "One of the best examples of which is granite, like this obelisk." "Granite is an exceedingly hard rock, used sparingly throughout all the ancient civilisations, mostly in ornamental statues and for ornate surfaces." "But this wasn't the rock that changed the shape of Roman architecture." "The magma wasn't always destined to become rock like granite." "Three million years later, the geological make-up underneath Italy had changed quite dramatically." "The huge force of the collision between Europe and Africa had created a system of fractures and cracks under Italy." "And it was this that would lead to the formation of the Italian volcanoes, by changing the pathway of the molten magma." "We're all back at the start point once more, 100 kilometres below the Earth's surface." "My mini tour group is once again newly formed hot, molten magma." "Let's go!" "Because of all the cracks and fractures, my magma tour group can now take a much faster, more direct route, heading across the square toward the Earth's surface." "It's a bit like taking the geological motorway rather than the scenic route." "All of those new cracks in the Earth below Italy effectively opened up a much clearer pathway for the liquid magma." "Before it had a chance to cool and solidify, the molten rock would have swiftly risen to the Earth's surface." "The result was a volcanic eruption." "Go!" "But hold on, the magma that escaped onto the Earth's surface could take on a number of different forms." "Which form was determined by the effects of trapped gas." "This gas is mostly high-pressured water vapour, which comes from the surrounding rocks." "Just like in this can of beer, within the liquid magma are bubbles of gas." "If that gas escapes slowly... then the magma arrives at the surface relatively calmly and oozes out as molten rock." "But if the gas remains trapped in the magma, then pressure can build up." "And when the molten rock emerges at the surface, the gas escapes all at once..." "Just as my bubbly explodes as froth, the pressurised volcanic gas breaks up the erupting magma into tiny pieces." "The result is a cloud of volcanic ash." "This is exactly the type of violent gassy eruption that took place here, in the still active Campania region, near the town of Pozzuoli just outside Naples." "An eruption in this area 12,000 years ago produced vast quantities of ash." "And it's ash, these tiny fragments of rock, which is the Roman geological jackpot I've been going on about." "Ancient Roman builders thought they could put this volcanic ash to some good use." "While making up their building mortar, they discovered, instead of mixing up the usual combination of lime and sand, that if they mixed up lime with the ash, it produced an interesting result." "The Romans created a builder's mortar with super strength, which even set in the wet." "It turns out, the explosive process that had created the volcanic ash gave it very special chemical properties." "When they mixed volcanic ash with the lime, the two substances reacted in an intimate way, forming very strong and irreversible bonds." "But the ash was to play an even more important role." "It was a key ingredient in a uniquely Roman innovation." "The final stroke of genius was to combine ash mortar with lumps of rubble." "It produced a building material that the Egyptians and Greeks could only have dreamt of... a DIY rock called concrete." "The Roman concrete was amazing stuff." "It set quickly and was waterproof, great for aqueducts and baths." "It even set under water - perfect for harbours." "The Romans also created a very durable building combination by using concrete with their kiln-fired mud bricks." "And don't be fooled by all this marble." "Most of it hides bricks and concrete underneath." "Because it could be moulded, concrete was perfect for building all kinds of new shapes." "It was then that the Romans discovered... the arch." "Now the Egyptians and Greeks had arches, but they mainly used them below ground for vaults and sewers." "It was the Romans that realised how valuable they'd be above ground, and they made extremely good use of them." "Coliseum." "Finished in AD 80 by Emperor Titus, the Coliseum was the centrepiece for Roman revelry, holding over 50,000 spectators." "That's more than your average Premier League football stadium." "It was here they staged the famous gladiatorial games, pitting Herculean warriors against each other, and assorted wild animals." "The whole structure of the Coliseum is supported by hundreds of arches." "The arch is so good at its job because of the way it distributes weight." "The two sides of the arch push in against each other." "This means that the weight above is never pressing down the middle." "Instead it's pushed out to the sides and down through the base." "Unlike the post and lintel set-up, with its stressed-out crossbeam, there's no tension in an arch." "This means it could not only hold up a great deal more weight, but stretch across much wider gaps." "It was the innovation of the arch, combined with their magic concrete, that the Romans were able to produce arguably their greatest architectural achievement." "This is the Pantheon, the king of all Roman temples." "Located in the heart of the city, it is one of the best-preserved of all the ancient Roman buildings." "Completed around AD 125 by Emperor Hadrian, the word Pantheon literally means "all the gods", to whom this breathtaking temple was dedicated." "To me, the Pantheon is the pinnacle of Roman building ingenuity." "Now from here, it may look like a rectangular Greek temple, but go inside and you can see just how the Romans changed the shape of architecture." "They created a vast circular building with an enormous concrete dome roof." "This giant round building has a roof stretching over 43 metres across." "It was the largest unsupported span the ancient world had ever seen, and it would be well over a thousand years before anyone would better it." "In the middle of the roof is a whopping great big hole, or oculus." "This allows sunlight in to light the building throughout the day." "What amazed everyone was how this huge roof stayed up, apparently suspended in mid-air, with nothing to support it." "Unlike the colonnaded temples built by the Greeks, or the column-packed halls of Egypt, the Romans had created a building with an incredible amount of internal space, completely uncluttered by any obvious support for the roof." "The dome was constructed as a perfect hemisphere." "If you think about it, the whole roof is effectively a circle of arches." "This means there's no tension in the central structure itself." "Instead of weight pressing down from the middle of the dome, it all gets pushed out to the sides and down through the base." "The weight is then further supported by a series of concrete and brick arches built into the lower walls." "It's a pretty impressive building, but the ever-practical Romans had essentially just copied nature." "Take my egg." "It's basically two domes joined together." "It may look fragile, but it's actually a very strong structure." "Now, the span of the egg dome is 30 times greater than the thickness of the shell." "And it turns out the dome roof here is exactly the same." "The Pantheon is really a giant egg." "The construction of this colossal man-made egg ultimately relied on geology to provide the right building materials." "But it wasn't just the volcanic ash." "The Italian volcanoes also provided the Romans with a whole variety of different rocks." "The builders of the Pantheon then added these to the ash cement to produce custom-made concrete." "Down at the bottom, for the foundation walls, they needed to make up the concrete with something heavy and strong." "So they used basalt." "This is a type of lava that's spewed out of the volcano as molten rock and then sets solid." "It's very dense and incredibly durable." "Up in the middle section, to reduce the weight, they used something a bit lighter." "A rock called volcanic tuff." "And the reason it's not so heavy is because it's actually ash that's been compacted over time to form a lightweight rock." "High up at the top of the dome, they had to have incredibly light concrete to keep weight to an absolute minimum." "So they added pumice to the mix." "Now, like ash, pumice is made when gassy magma explodes out of the volcano to produce an ultra-lightweight rock full of air bubbles." "It even floats on water." "Thanks to volcanoes, the Romans had the perfect materials to create a unique domed building." "The Pantheon stands as one of the greatest achievements of Roman architecture and engineering, and it set the shape of things to come." "The ancient monumental buildings that I've seen in each country all have very distinctive forms." "And it seems to me that these were dictated by much more than just the beliefs and traditions of the different civilisations." "The shape and style of ancient buildings was also determined by the geological hand that each country was dealt, and this was a card game that started millions of years before man had even evolved, right back when the Mediterranean was first formed." "Geology provided the ancients with the raw materials." "And by taking advantage of what each different country had right on their doorstep, the great civilisations each left us unique monuments that we can admire today." "The Egyptian pyramids are a tribute to sedimentary rock." "Rectangular Greek temples are a triumph in marble." "And gigantic Roman domes are all thanks to volcanoes." "Subtitles by Craig Dunn - BBC Broadcast, 2005" "Email us at subtitling@bbc.co.uk" "For further information on Open University programmes, please go to..." "Our modern world is full of colour." "And almost every shade is available to us." "Manufactured, and ready for use." "As human beings, we seem to be born with the need to represent our world through art." "Modern science has provided us with a rich, vibrant palette of paints." "Deep blues, beautiful greens, flaming yellows." "We have these thanks to a quest for colour which began 15,000 years ago." "And gave us everything from these magnificent cave paintings in France..." "..to Tutankhamen's treasures in Egypt." "And the Alhambra in Spain." "But how have we managed to progress from just a few basic shades to the riot of colour we have today?" "As a geologist," "I'll show you that it's all down to understanding what's beneath our feet." "The answer is here, in the rocks." "Our quest for colour begins here in France's Dordogne region, at the caves of Lascaux." "These are among the first images ever painted." "They came to light in 1940 when some children caught in a storm stumbled in here." "What they discovered had been hidden for 15,000 years." "These cave paintings here at Lascaux show us that from very early on humans went to great lengths to recreate the world around them." "The images on the cave walls are a sort of stone age menu." "Reindeer, wild boar, all the food that early man hunted for survival." "But why, when catching food for our ancestors was a matter of life or death, did they take time away from the hunt to paint these?" "Well, one theory is that Stone Age artists believed that if they painted a picture of what they fancied for dinner, it would give them a better chance of catching it." "Which, if it were true, would have made the effort of painting it nearly as important as the hunt itself." "These paintings, for our ancestors, may well have been a sort of giant good luck token." "It's all very lovely, but from a modern perspective isn't it a little bit lacking in colour?" "Even a wee bit dull?" "I mean, these artists are trying to picture the world." "Where is the blue of the sky, or the green of the grass?" "Why limit yourself to reds and browns?" "The answer is in my lunch." "Here's a perfect place for my picnic." "Roussillon, in the south of France." "It's also an ideal spot to explain where the cave painters found their colours." "Think of this mug of soup as the world." "Right now it is a swirling mass of ingredients." "But as it cools down, things separate out." "The heavier pieces fall to the bottom." "Some linger in the middle." "And the lighter ones rise to the top." "That's what happened when the earth was formed, 4.5 billion years ago." "Still hot from the processes that formed it, the planet began to cool down." "The heaviest materials sank to form a dense core." "Stuff that wasn't as heavy, the mantle, stayed in the middle." "The lightest material rose up to the surface to form a crust." "It's about 70 kilometres thick and it's here that the cave painters found there colour." "It may not look like it, but this is the Stone Age equivalent of an art shop." "These reddish rocks are called ochre." "They're a combination of iron and oxygen, and they are abundant in the Earth's crust." "These iron oxides have been a source of artists' pigments for thousands of years." "Artist David Atkinson brings his students here to paint with colours literally scraped from beneath their feet." "Wow." "Where are the rocks then?" "I'm just looking at colour." "And in fact you don't actually need paint to paint here because the colour is all around us on the ground." "This is your palate." "Yeah." "It is a mixture of sand and the ochre pigment." "Depending where you take it from it goes from very dark, down here, really... a pure yellow ochre." "So you can just physically use that and mix it either with some kind of oil to make oil paint, or with gum arabic to make a kind of watercolour paint." "So you wouldn't use blood, or urine or something like that?" "Because that's what I heard the cave artists used to use." "They did, and animal fat." "But it's all actually the same method." "You're taking natural pigment and using some kind of a glue to stick it on the paper." "So we've got the actual stuff here on the ground, and you can just scrape a bit out with a palette knife." "Then you've just got water, a bit of binder and you've got paint." "So the first painters used whatever they could get their hands on." "Luckily for them, nature had provided some basic colours at the surface." "The ochre for the reds and yellows." "And another crust material, a combination of oxygen and manganese, was perfect for the browns." "For the whites we saw in the Lascaux caves, they used natural chalk." "The blacks came from the charred remains of sticks from the fires." "With just a few basic colours, our Stone Age ancestors set out to represent their world." "And perhaps to improve their chances of a decent meal." "The paintings weren't intentionally dull, they were making the best of what was available to them." "Our cave painters didn't know that they were literally just scraping the surface." "They were too busy staying alive to discover that as well as reds and browns, the earth had a whole load of wonderful colours." "It would take 10,000 years and a civilisation obsessed not with dinner, but with death, to unearth this new palette of colours." "Egypt." "Thousands of us come here every year." "Drawn to the rich sights and sounds of this colourful country, which was home to one of the first great civilisations." "One which transformed the rocks on its doorstep into the most breathtaking monument." "And there are no better examples of this than the pyramids." "The Sphinx." "The temple at Carnac." "And the tombs here at Luxor." "There are about 400 of these tombs dotted around the West Bank of the Nile." "Each one containing the colourful stories of life and times in ancient Egypt." "Look at these paintings!" "It's incredible to think that all of this detail has survived for 3000 years." "But what amazes me most is the colours." "Look, here's the browns and reds and blacks and whites that we saw in the caves in France." "But look over here." "We've got bright yellows and oranges." "Greens and blues." "Compared to the cave paintings, these are positively psychedelic." "But what was it that made artists who painted these go to all this trouble?" "Particularly when the tombs would be sealed, and the only visitor was dead." "The ancient Egyptians believed that the world was created from chaos, and life was a constant battle against descent back into that chaos." "And as believers in life after death, they were desperate to make sure that their afterlife would be orderly and completely chaos-free too." "These pictures of bountiful harvests and healthy, happy people going about their daily business aren't how life really was an ancient Egypt." "They're how the ancient Egyptians wanted life to be after they were dead." "These images were a kind of insurance policy, and needed to be as realistic as possible." "Which was why getting the right colours was so important." "Greens to paint the lush vegetation." "Yellow to paint the sun." "And, most important of all to a civilisation that depended on it, blue to paint the life-supporting Nile." "But where did they get this richer palette?" "Fortunately for the Egyptians, thanks to a chain of geological events, the colours they needed were actually right on their doorstep." "Remember my soup?" "How when the Earth was forming, lighter materials ended up near the surface to make the Earth's crust?" "Well, along with the iron and manganese oxides that gave the cave painters their reds and browns, there were other materials in the crust." "And it was those that held the key to the ancient Egyptian colours." "When the earth was first formed, these colours weren't concentrated together like the chunks of red and brown rocks we saw in France." "Instead, they were scattered in tiny amounts throughout the crust." "Getting hold of them would be like trying to pick out the individual grains of sugar in this cake." "But over millions of years those particles were brought together in concentrated form, so they could be used by the ancient Egyptian tomb painters." "To show you how that happened," "I'm going to travel back 30 million years." "This lava lamp may not be 30 million years old, but it does help to explain how the ancient Egyptians got their colours." "The light bulb in the base of the land heats the wax making it expand and rise towards the surface." "This is exactly what is happening deep beneath our feet." "Heat, trapped inside the Earth from when it was formed, causes the rock in the mantle to get hotter and expand." "As it expands, this plasticky molten rock forces its way up into the crust, moving very slowly - just a few centimetres a year." "As it pushes up, it causes the crust to crack." "It's these cracks and fissures which are crucial to the whole process, because they create places for the colour particles to collect." "To show you how the colour collects in those cracks, I'm going to need some help from a few handy tourists." "The people down there are common crust minerals." "But scattered amongst them, too small for us to see, are tiny scraps of colourful materials." "Excuse me, can you help me do some geology?" "No, thank you." "No?" "OK." "Excuse me, I know this sounds daft, can you put that green hat on and just stand up?" "'The green hats represent particles of copper, which is only present in 'miniscule amounts as little as 14 parts per million, scattered throughout the Earth's crust." "'The essential ingredient to bring them together in the cracks is water." "'This water is circulating around the crust because it has been heated by a hot molten rock.'" "OK, let's go." "OK, I am hot water and you are copper. 'I'm playing the part of the hot water." "'Acting like a scavenger collecting the copper by dissolving it.'" "I need you to stay there for now." "I'll leave you just there, OK" "Just through the cracks, leave you up here." "Leave you there." "Could you now put your heads in together?" "That's it." "However, as the water gradually cools, the tiny particles of colourful materials are deposited back out of solution." "Except this time, they're not spread around." "They've all been collected into one place as a concentrated vein or mineral deposit." "These are the Red Sea Mountains." "On the face of it, this looks like nothing more than a barren and inhospitable landscape." "But this is where the ancient Egyptians found the copper seams that provided that all important green for the tomb paintings." "Today, these mountains are an attraction for the more adventurous tourist." "I've hitched a ride to come and see what else was on offer for those ancient painters." "The Egyptians took advantage of what geology provided because, thanks to millions of years of weathering and erosion, the colourful minerals could be found close to the Earth's surface." "The Egyptian tomb painters could simply pluck the colourful rocks from the ground." "This was the Egyptians' giant paint shop." "Look at this!" "It's a ridge of dark volcanic rock that was forced up through a crack in the Earth's crust." "It's from rocks like this that the ancient Egyptians got the minerals they were looking for." "This is orpiment." "Grind it down and it gives you a vivid yellow." "This is realgar - it makes orange." "And this is malachite, it's made from copper we saw being collected by hot water reacted with other substances to form this beautiful green colour." "These are the colours the ancient Egyptians needed to paint the world they wanted on their tomb walls." "But there was one colour here in these paintings that the ancient Egyptians didn't find in the mountains." "Blue." "The discovery which produced this colour would change not only art, but the world for ever." "The ancient Egyptians were fortunate." "The land they occupied provided them with everything they needed to build a successful civilisation." "An abundance of rock for their temples and monuments." "And plenty of food, thanks to the Nile." "And for the things they couldn't produce themselves, they relied on an extensive trade network." "Nowadays, markets like this are mainly for tourists." "But 6000 years ago, these were where the ancient Egyptians exchanged linens for Mesopotamian oils and later salt fish for Venetian wood." "It was also where, thanks to simple blue trinkets like this, that they realised there might be a way to get their hands on the blue colour they always wanted." "Just like today, at markets like this, the Egyptians could buy beautiful blue objects made from a rock called lapis lazuli." "This was brought to Egypt by traders who had travelled thousands of kilometres over land from Afghanistan." "But this exotic import was expensive." "If the ancient Egyptians wanted to paint beautiful blue water and sky in the tombs, they would have to find a cheaper alternative." "Somehow, they had to come up with their own formula." "But just how do you make the colour blue?" "You've got to break a little with yellow." "And a little with maybe red." "How do you make the colour blue?" "That's blue by painting it." "By...?" "Painting colours." "In Mexico they have a mollusc, like a sea animal that makes blue." "But I think it's more purple than blue." "It's blue I want." "White?" "No, yellow." "You mix the colour white with some colour." "White?" "White, yeah." "White and what?" "Er, yellow." "Maybe white and yellow." "Maybe." "I'm not sure." "Blue." "Like your eyes." "Thank you very much." "No, no, no, believe me." "Yellow and red." "English?" "Yes, but we are in a rush." "Oh, you're getting a bus." "What do I win?" "What do I win?" "I'm not sure I believe you!" "No, now you believe me." "You have to believe me." "Because I'm a doctor in colours." "Well, blue is a primary colour." "Egyptians couldn't make it by simply mixing other pigments available to them." "They would have to find another way." "Something more ingenious." "The Egyptians did make the blue they were after by mixing." "But not by mixing colours." "At the Centre for Egyptian Antiquities in Cairo, chemist Dr Askandir has been using the green malachite rock that the ancient Egyptians found in the mountains to mix up this ancient recipe." "So, how do you make this fantastic Egyptian blue?" "I think that the Egyptians have recognised some different colours in nature." "They have chosen some things like this rock, which is composed of copper, to try to mix some blue colour." "First they take this copper rock and then they mix it in a grinder like this." "Crush it down." "And they add white sand, from there." "This is just desert sand?" "Desert sand." "It usually contains some impurities like calcium carbonate." "So there's limestone and salt in that sand already." "And then we are going to put it here." "'In Egypt, natural forces weren't transforming the earths materials into blue rocks." "'So the Egyptians had to give nature a helping hand." "'The tomb painters used the heat from the kilns to transform a green rock into a brand new colour.'" "This heat, now we know it's up to 1000 degrees." "1000 degrees?" "And by the end, this is the result." "And here it is." "A beautiful blue substance from one of the first ever chemistry experiments." "It's a miracle!" "It's a miracle" " I guess it is." "Soon, the artisans of Egypt are using this blue glaze to decorate all sorts of things." "And it could get used as a pigment, known as Egyptian blue." "You want to buy, sir ?" "No, thank you very much." "All right." "These were exciting times for art." "Although the Egyptians didn't understand why it happened, they were clever enough to realise that they could take the Earth's raw ingredients and, with a little bit of heat and other manipulations, make completely new materials." "Unlike the colours we've seen so far, Egyptian blue wasn't dug up from the earth and ground down to make pigment." "It was the world's first man-made colour, cooked up to a recipe over 4000 years old." "It was a huge step forward." "Although this blue was man-made, it had been created from a rock." "Geology and chemistry had collided to make colour." "And this was just the beginning." "Another colour Egyptians used in their art was even more popular than their blue." "Gold." "11 kilograms of gold was used in Tutankhamun's mask alone." "That's the equivalent weight of 11 bags of sugar." "And this solid gold coffin needed over three times that amount." "The ancient Egyptians obviously loved the stuff." "But to satisfy the need for this precious metal they had to travel hundreds of kilometres into the remote and inhospitable desert." "Risking thousands of lives to mine it." "But what if man didn't have to rely on what he found on the earth?" "As well as colour, the ancient Egyptians' early experiments had transformed ordinary ingredients into valuable products like bronze and glass." "What if it were possible to use these techniques to make something as rare and valuable as gold?" "Now, with science at their disposal, the Egyptians believed that they could cheat nature and manufacture their own precious metal." "Try as they might, all of their efforts ended in complete failure." "But the quest to make gold didn't end there." "The Arabs were about to take up the challenge, with unexpectedly colourful results." "Of the 50 million of us who visit Spain every year for the sun and sangria, at least 2 million also manage to drink in some culture." "By visiting this the wonderful Alhambra Palace." "It was built by some of Spain's first visitors." "Ones who stayed, not for a two week holiday, but for seven centuries." "The Arabs." "Originally from the Arabian peninsula, they were on a mission to spread the word of Mohammad." "They conquered much of the Middle East, and then travelled west along the North African coast." "Arriving in Spain in 711 AD." "This is fantastic." "It's one of the world's most amazing buildings." "From an ideological perspective, the Arabs left behind something far more important than beautiful architecture." "The clues are all here in the art." "When I look at these complex geometrical designs" "I see a civilisation fascinated by science and maths." "The Arabs produced these designs using knowledge they had picked up and developed from countries around the Mediterranean." "By the time they reached Spain, over a 1000 years ago, there was one particular idea they had acquired on their travels which they thought might just hold the key to making gold." "It was the ideas of the Greek philosopher Aristotle that they found especially interesting." "He was one of the first to attempt a scientific explanation of how the world was made." "And he thought it came down to just four substances - air, earth, fire and, of course, water." "That theory, if true, meant that all of the materials on the planet came from combinations of those four "essences", as he called them." "So, logically, you could use those four ingredients to make any of the materials on the earth." "Armed with Aristotle's ideas about the world, the Arab alchemists set about putting them to the test." "They were convinced they now understood how to carry out the ultimate transformation." "Something that would have made the Egyptians green with envy." "To turn dull, useless rock into beautiful, valuable gold." "And here in Almaden in central Spain, they appear to have found the perfect rock to effect that transformation into gold." "Almaden was a working mine for over 2000 years." "Today, it is in the safe hands of ex miner Anguel Hernandez." "This is it, yeah?" "Yes." "Here it is." "Wow!" "Look at that." "Look." "This is it." "This is what I've been looking for - cinnabar." "It doesn't look much like gold, but it does sparkle." "And this must have caught the attention of the Arab scientists." "They wondered whether cinnabar contained similar proportions of the four essences of gold." "If they could re-combine the essences, in slightly different proportions, then maybe they could make gold." "But first, the Arab alchemists had to unmake the rock." "Cinnabar is a combination of mercury and sulphur." "To make gold, the Arabs thought they would need to extract the mercury and re-combine it with the sulphur using different proportions." "So we've got our lovely cinnabar." "But how did the Arabs get the mercury out?" "First they broke it into small pieces and crushed it." "So you crush it like this and break it down into small pieces." "Then what?" "They cook it in the furnace at about 300 degrees centigrade." "300 degrees centigrade?" "And that would bring out the mercury?" "Yes." "Like this." "That heavy, isn't it?" "That's amazing." "Yes." "And look." "That's incredible." "When you see it like this, it's not surprising that the alchemists thought they would get gold." "This is weird, weird stuff." "Yes." "Weird, yes." "But not the gold they were after." "Whatever combination of mercury and sulphur the Arabs tried, they still couldn't achieve their ultimate goal." "Alchemy was founded on a fundamental mistake." "All the materials of the world are not made of essences." "The Arab alchemists had failed to make gold." "But they did manage to make something that in its time, and weight for weight, was nearly as valuable." "When they heated Mercury and sulphur, they made this." "Vermilion." "During their experiments to make gold, the Arab chemists had focused on some of nature's most colourful rocks." "The results were greens, yellows and rich vibrant red." "These colours were embraced by artists and soon spread around the Mediterranean." "For the next 400 years the colours the Arabs discovered in their labs, transformed the once limited artist's palette into a rainbow of different colours." "By the 16th century Renaissance artists like Veronese were using just about all of the colours then available." "It's beautiful!" "But to me, it's so much more than just a picture." "It is like a geological map unveiling the secrets locked up in the rocks." "It's amazing to think that all this comes from rocks." "This is iron oxide - ochre." "It's one of the colours used by the cave painters." "And it's still here, 15,000 years later scraped up from the ground to produce these reddish browns." "Malachite, the rock we first saw in Egypt, which is made by hot water scavenging its way up through the Earth's crust." "It is here, in these greens." "And this is vermilion - that vivid red colour that the alchemists created from mercury and sulphur, found in cinnabar." "These were exciting times for Renaissance painters." "The development of these colours provided a whole new impetus for artists." "They started to mix their pigments with oil rather than egg or water." "Which helped them achieve greater shade and tone." "This, along with the greater range of colours, allowed artists to paint subjects in a much more real and rounded way." "Lifelike flesh tones, subtle hair colours and drapery so good you could almost touch it." "But there was one more rock that helped artists to make their pictures even more realistic." "But that would take a few centuries and several wars between England and France." "Paris." "Famous for its culture, its architecture and fashion." "However, it wasn't always such a romantic destination." "By the end of the 18th century, the city had played host to a bloody revolution." "And seen thousands die in wars with England that lasted, on and off, for nearly 50 years." "With all that fighting, both sides were always on the lookout for that winning advantage." "And the secret weapon would be a rock, graphite." "Unfortunately for the French, the best graphite was in England." "The English arms manufacturers discovered that instead of casting their iron cannon balls in sand, graphite moulds were much better." "The balls from the graphite moulds were so smooth that they flew out of the English cannons faster and travelled further." "Graphite became an invaluable to the English military campaign." "But its properties also came to the attention of artists." "It wasn't a colour as such, but artists saw its value as a revolutionary new tool." "Graphite is an ideal drawing material." "It's portable, it doesn't smudge easily or run when wet." "It makes strong, dark marks." "But more importantly, it can be used to create shade and depth." "The reason graphite was so good for drawing lies in the way that it is made." "Imagine this wafer is a lump of graphite." "You can see that I can pull the layers apart." "There's very little holding what above to what's below." "And that is exactly how graphite is made." "Graphite has lots of sheets of carbon atoms that are joined together horizontally, but which have few vertical connections between the layers." "Which means that the layers can slide over each other, and explains why graphite is soft and slippery." "This makes it not only good for making really smooth cannonball moulds, but also ideal for pencils." "As it's dragged across the paper, the layers are pushed off leaving a clean, hard mark behind." "It seemed in the war of the pencil that the French were to be the losers." "They, like the rest of Europe, had only low quality deposits of this fantastic material." "They were forced to pay a very high price to the English, who controlled the supply." "But in 1794 a French inventor called Henri Conte managed to strike a surprise attack and deal the English a decisive blow." "He discovered that by mixing low quality graphite with clay he was able to make a pencil that was much better than one made of pure, high quality graphite." "Remember all those "HBs"" "in art class?" "Well, the H tells you how much clay there is." "The higher the H, the lighter the mark." "And the B tells you how black it is." "The more Bs, the more graphite and the darker the mark." "The combination of this new product gave artists much more flexibility." "And they didn't have to pay the English for the pleasure." "In fact, pencils like the one Conte invented, dominate the market today." "So it's thanks to cannonballs that artists finally got hold of the perfect material for drawing realistic pictures." "Can I see what it is, yet?" "Can I have a look?" "Thanks." "Excellent." "You made me look pretty." "You gave me a small nose as well, I'm forever grateful." "With the pencil, new techniques and the colours from the Arab alchemists, artists are better equipped to represent the world as they wished." "However, there was a problem." "The colours contained a major flaw." "The very paints used to create these masterpieces also threatened to destroy them." "If we look again at Veronese's masterpiece, we see it's not actually as colourful as he originally intended." "Down here, in the corner of the painting, the dwarf's clothes have faded." "The jacket and trousers were originally deep blue." "But unstable paint has meant the blue has virtually disappeared." "On Veronese's "The Marriage Feast at Cana", the results haven't been disastrous." "But in some cases, the paints have faded or corroded, destroying the vivid colours that the artist had used." "Worse still, the paintings contain a dark secret." "The paint itself is lethal." "The white here contains lead." "And the orange realga, arsenic." "Artists were working with deadly substances." "And possibly the most famous casualty of colour was none other than the French emperor, Napoleon himself." "Napoleon, do you know how he died?" "Shortage of breath?" "That's a good one." "How did Napoleon die?" "Well, I think it's much argued about, isn't it?" "Because I don't know." "He was old?" "I don't know." "By falling into an iceberg." "Falling into an iceberg?" "That's fantastic!" "No, I don't know." "Committed suicide?" "I didn't go to school for that long!" "Well you could guess how people die." "He was shot or something." "Shot?" "Did Josephine kill him?" "You guys have a camera crew out here to figure out how Napoleon died?" "Yeah." "It is now suspected that what finally brought an end to France's greatest general was colour." "Following his defeat at the hands of the English," "Napoleon was exiled here to the bleak island of St Helena." "The house has since been redecorated." "But the original wallpaper was painted with a green pigment." "A Swedish chemist, Scheele, made the green colour by mixing copper sulphite with arsenite." "In damp conditions, the arsenic and the paint could react with the air to give off a poisonous vapour." "Nearly 200 years after his death, Napoleon's hair was tested." "Residues of arsenic were found, which confirmed that he was exposed to this toxic gas." "Already sick with a stomach ulcer, it is thought that this may well have hastened his demise." "Colour, it seems, could kill." "And artists took great risks with the paints they chose to create beautiful paintings." "But something was about to happen that would revolutionise art and make colour non-toxic." "By the time Napoleon died in 1821, chemists had already begun a series of discoveries that would eventually produce colours that were long lasting and safe." "Like the alchemists before them, this new breed of chemists weren't looking for colour." "Their experiments were driven by the demands of the Industrial Revolution." "But the results would create some of the most remarkable art the world had ever seen." "It was all because of this." "Air." "Aristotle's theory that air was one of the four essences which made everything, was still widely held centuries later." "But in the pursuit of industrial riches, a new generation of chemists would question everything, and consign Aristotle's ideas to history." "Antoine Lavoisier was a French chemist." "His experiments into the nature of air would lead to the creation of a whole new rainbow of safe, long-lasting colours." "Lavoisier decided that air was made of two substances - oxygen and nitrogen." "Air wasn't a pure substance after all." "It was a mixture of two." "Importantly, he realised that oxygen was a pure substance." "Try as he might, Lavoisier simply couldn't reduce it or break it apart into simpler components." "Oxygen wasn't made of anything else." "Lavoisier called oxygen an element." "The list of elements soon began to grow." "Things like copper, iron and mercury, extracted from rocks, had long been known to man." "But now they were seen in a new light." "It was discovered that they too were elements." "And this understanding of the elements would revolutionise art." "Elements, not Aristotle's essences, were the building blocks of the Earth." "But to understand exactly what elements are, we need to go back to the ultimate geological event." "One that happened before even time existed." "The Big Bang." "This may look just like a mass of people, but to me it is the geological past." "You see tourists, I see a swirling mass of the first particles." "Scientists don't yet know how it happened, but at some point 14 billion years ago, the universe exploded with an enormous bang." "It was the beginning of time, and in the next fraction of a second particles were created." "Neutrons, electrons and protons." "It was from these particles that elements like Lavoisier's oxygen would eventually be made." "And it's from these elements that industrial chemists would get a whole new palette of colour." "With the help of these unsuspecting people, I am going to show you what happened." "'These balloons represent the basic particles - 'electrons, protons and neutrons.'" "Okay, so the red balloons here are electrons, the blue balloons are neutrons and the yellow balloons are protons." "And I want you to start swirling around in different directions." "'Some time after the Big Bang, the swirling particles 'started to clump together to create elements, or atoms." "'It is now understood that atoms are the basic building blocks of our world.' OK." "I'm now going to start to make some atoms." "Proton, neutron, electron." "OK." "So you guys are a gas, you're helium." "To make helium into another element, I need three more balloons." "So I've got one more neutron." "Can I invite you in?" "Mr Proton in." "Now I've got an atom with three protons, three neutrons, three electrons." "You guys are another element." "You are lithium." "As the universe developed, other elements were formed." "Like this one" " Lavoisier's oxygen." "It's got a eight protons, neutrons and electrons." "Right, okay." "I need some more." "Each element is made up of all three particles." "But it's the number of protons that make each element a distinct substance." "So, you guys are now oxygen." "Take a proton away...excuse me, can I move you over here?" "..and now oxygen becomes a completely different element." "In this case, it's nitrogen." "The Big Bang created 92 fairly stable elements." "Unfortunately, Lavoisier never knew this." "The poor chap lost his head to the guillotine in the French Revolution of 1794, by which time only 33 element had been identified." "But the search that he started, which gradually found the missing elements, would change the world and art forever." "And it's here in Paris that we can see the results of this quest." "Driven by the demands of industry, chemists discovered more and more elements." "Once they had found the elements they could begin to combine them." "Their experiments produced useful and valuable new materials." "These fuelled the Industrial Revolution and found their way into factories and homes throughout Europe." "The Eiffel Tower was built in 1889, for the centenary of the French Revolution." "It stands as a celebration of this frenzied industrial change." "The alchemists had begun the processes of unpicking rocks, extracting stuff they wanted, like mercury and sulphur..." "..and putting it back together again to create something new." "Now, by understanding elements, chemists would unpick the whole world." "As they put it back together again, they made practical things like stainless steel, plastics and medicines." "Like the alchemists before them, the by-product of this quest for wealth was colour." "Here in Paris's Musee D'Orsay, we can see some of the finest examples of the colours created by chemists in the laboratories." "These Impressionist paintings today remain many times more valuable than gold." "Artists like Renoir, Monet and Pissarro eagerly embraced the products of the chemist laboratories." "They took full advantage of the bright blues, the greens, and the violets by deliberately placing new, vivid and contrasting colours next to each other." "The effect is that things would appear brighter in combination than they would have on their own." "They weren't painting the world that they wanted, or even the world as it really was." "It was how they felt about it." "They wanted to bring their emotions, sensations, their impressions to life." "Every year, thousands of us come to wonderful sun-drenched Provence." "Enjoy the beautiful countryside and charming towns." "These same sights were an inspiration to the next generation of French artists." "Van Gogh." "Gauguin." "And Cezanne." "They turned their backs on the city in their quest to paint the world they loved." "By the late 19th century, about 70 of the elements had been discovered." "Including some of which, with the help of modern chemistry, would prove to be the most colourful of all." "Ironically, the Post Impressionists used the by-products of an industrialised and grimy world to paint a completely different world - one that was rural and unspoilt." "Fortunately for us, Provence has remained as they'd have wanted." "Unspoilt." "A place where we can still escape to, if only for a few weeks a year." "This is Arles, a Provencal town made famous by the Van Gogh and Gauguin." "They embraced the town and immortalised it in their paintings using vivid, exciting colours made from a variety of newly discovered elements." "In 1797, a French chemist called Vauquelin took a rock discovered in Siberia and extracted a new element chromium." "It turns out this new element produced a bright new paint, chrome yellow." "Artists like Van Gogh loved it." "And he used it to paint some of his most famous paintings, like The Sunflowers and this - The Asylum Garden at Arles." "And this view was painted by Van Gogh's friend, and fellow artist, Gauguin, in 1888." "To paint these trees, he used a red pigment made from one of the new elements." "Cadmium." "And for the soft blue sky, he chose another - cerulean blue." "Of the 20 colours regularly used by the Impressionists and Post Impressionists, 12 are thanks to the discoveries of modern chemistry." "So when we look at these paintings, we're not just looking at great art, we're looking at the results of a revolution that started with Lavoisier and his oxygen." "But what nobody, not the chemists, the artists, the alchemists, or the ancient Egyptians understood was what made rocks colourful in the first place." "Where is colour from?" "Where do we get it made?" "What?" "How do you make colour?" "Where does it come from Oh, colours." "Oh, Disney World!" "Disney World has 'em!" "What?" "Disney World?" "They own the colours." "Colour is an expression, I would say, of your personality." "Just colour, any colour, anywhere." "How do we get it?" "In Africa, perhaps." "Could be." "Colour is amazing." "It is something that you see." "It is something that you feel." "Colour just runs through your veins." "I used to know the answer, I studied this!" "Your teacher is now going to be very upset." "Maybe not necessarily God, maybe a certain figure, sees it as an emotional structure." "Right..." "I'm kind of baffled." "It is a difficult question." "By the time the Impressionists were experimenting with vivid colours, scientists were beginning to find the answers." "They included a Russian chemist called Mendeleev." "He used playing cards." "One for each element." "By arranging and rearranging them into all sorts of possible combinations, he worked out how to fit them into a table, so that the elements with the same chemical properties were grouped together." "There were question marks on some of the cards, because he knew there were still more elements waiting to be identified." "Each column is like a family of related elements which shared similar traits and characteristics." "It's this arrangement that was the basis of the modern periodic table." "This table is the key to unlocking all the materials of the Earth." "By organising the elements into this table, he also helped chemists understand where colour actually comes from." "Here's iron." "Mixed with oxygen this gave the cave artists our red ochre - iron oxide." "And here's copper." "Volcanic processes turned this into the ancient Egyptians' green malachite." "And here is Van Gogh's yellow chromium." "Now look at this." "All of the materials that made our colourful paints come from the same parts of the periodic table." "They're from the same family of metals." "These elements have got the same protons, neutrons and electrons as all of the others." "In this particular family, it's the behaviour of the electrons that actually creates all of that bright and wonderful colour." "To show you what I mean, I need to wait until it gets dark." "Colour actually comes from light." "Without it, as we can see once the sun sets, the world is a very dull place indeed." "In the 17th century, Isaac Newton shone daylight through a prism and saw this." "He had argued that daylight is actually made up of a rainbow of different colours." "Newton had discovered that each ray of light from the sun was in fact made up of seven basic colours." "Each one of these colours, like radio waves, had its own wavelength." "This is where the electrons and pigments are important." "What scientists in the 20th century finally realised was that it was only when white light, daylight, falls into something whose electrons can absorb the energy the light contains that we can see colours at all." "However, those electrons are picky eaters." "They only have appetites for light of a particular wavelength or colour." "Those appetites vary from one element to another." "Which is where our rainbow comes in." "Imagine something painted yellow." "When the white light falls on it, the electrons in the pigment pick out the yellow from the rainbow of colours and reflect it back." "That's why you see yellow." "All the other colours contained in the light are simply absorbed." "When you look at this yellow wall, you're actually seeing the only part of the rainbow that's left." "The yellow light waves that are being reflected." "What chemists realised when they looked at the periodic table, was that a certain group of the elements, the ones in the middle, that they called the transition metals, have particularly colourful appetites." "The electrons of these elements can absorb some of the colours contained in the rainbow." "But it's the other colours they reflect back that give the transition metals their colour." "That's why the periodic table was so useful to chemists when it came to creating colour." "Chemists finally understood which rocks were likely to produce colour." "But also, why they were so colourful in the first place." "We began with just a few shades." "But our quest for colour has ended with an almost infinite number of pigments." "Over thousands of years, we've learned to manipulate the earth." "First by scraping and gathering rocks from beneath our feet." "Later, by cooking up recipes using guesswork." "And finally, through an understanding of how the world is made, we began to combine elements." "At last, the Impressionists and the artists that followed were free from the constraints of a once limited palette." "A relationship had developed between geology and chemistry that would help art revolutionise itself, time and time again." "That is the way of art." "To find opportunity through technology." "And all this, so we can meet our instinctive need to recreate the world around us in a glorious, vivid colour." "Which is all amazing." "But I still can't paint!" "For further information on Open University programmes, go to " "The Mediterranean is full of beautiful vistas." "But this stunning scenery is more than just a feast for the eyes." "Throughout history, the landscape has had a major influence on how we believe our planet works." "As a geologist, I see rocks as an important driving force behind human history." "Here in the Med, geology has influenced everything from the extinction of dinosaurs to the existence of God." "I'm going on a journey to explore the way our understanding of the Earth has been transformed... from the time of the ancient Greeks right through to the present." "I'm going to uncover how, through the ages, the rocks beneath our feet have forced us to rethink our beliefs on how the world around us works." "Throughout human history, civilisations around the Med held a fantastic range of beliefs about how the world worked." "Here in ancient Greece, a whole legion of supernatural beings were believed to rule the earth." "There were numerous different gods to whom great temples were dedicated, plus assorted nymphs who lived in trees and streams... and a range of hideous monsters." "Your average Greek citizen believed that these beings were responsible for absolutely everything from love and hate to harvest and death." "The Greek gods, who looked down on the world from the top of Mount Olympus, appeared to be a vengeful bunch, ruling over the earth with an iron fist." "Not surprisingly, the ancient Greeks were keen to keep their mortals happy." "Otherwise they could be in for a rough ride." "One God they really didn't want to upset was the feared earth-shaker and ruler of the sea, the mighty Poseidon." "Poseidon was notorious for his bad temper." "Displeased, he would cause volcanoes to erupt, the earth to shake and the sea to surge." "The ancients bestowed lavish gifts on Poseidon in the hope that he wouldn't visit them with his wrath." "But despite their best efforts, through ancient Greek history, this particular god would often flex his muscles." "One place where Poseidon was said to have vented his fury with exceptionally devastating effect was here, along the spectacular Gulf of Corinth, in the North Peloponnese of mainland Greece." "Archaeologists believe that down there, on the plain behind me, stood an ancient and once-thriving city called Helike." "It was built as a sacred place to worship Poseidon." "But whatever the efforts to please and appease this irritable god, he struck the city with a terrible catastrophe." "On a winter's night in 373 BC, the Greeks believed that Poseidon became so angry with the townsfolk that he completely destroyed the city." "One day Helike was there, the next it had disappeared without trace, swallowed by the sea." "We now believe that the real cause of the catastrophe wasn't Poseidon's fury but this." "The Helike Fault, which has a habit of making the ground in front of it suddenly drop." "The Helike Fault is clearly visible as this sheer rock face which runs for over 30 kilometres." "It was formed naturally as a result of a geological of tug-of-war." "The Earth's surface is broken up into what are called tectonic plates." "The whole of Greece sits on the southern edge of one of those, the European plate." "Imagine this chocolate bar is the Greek part of the European plate." "We now know that that plate's actually being geologically pulled by its neighbour, the African plate." "Look what happens." "As the plate gets tugged, it stretches." "That's because the rocks deep underground are so hot that they act like the viscous, gooey caramel inside the bar." "But at the surface, the crust is rigid." "And just like the outer coating of this chocolate bar, it doesn't stretch." "Instead, it forms a crack which we see as a fault-line." "But it's not quite that simple." "The Earth's crust doesn't just open up, as that would produce a vast chasm." "Suppose the geological fault here at Helike is now represented by the gap between these two guidebooks." "When the rigid crust is pulled from either side, the fault moves by going on a slant." "But look at that." "One side of the fault goes up and the other side goes down." "This phenomenon was felt during an earthquake recorded here in 1861." "And here's the evidence." "During the 1861 earthquake, these deep grooves appeared." "They were created when, in a split-second, the ground on this side of the fault dropped down scratching the rock face as it went." "And this is the secret of how Helike was destroyed." "The ground beneath it was sent crashing all the way down to below sea level, allowing the waters of the Med to rush in and completely submerge the city." "Although catastrophes like Helike were believed to be down to the wrath of the gods, this particular disaster influenced one famous Greek philosopher to think differently." "In a the 4th century BC, it was Aristotle who provided what may have been the first germ of rational geological thought." "When catastrophes happened, Aristotle looked for more earthly explanations." "But in a culture where the gods were so important, this was a radical approach to understanding the world." "Aristotle was particularly intrigued by peculiar meteorological conditions that occurred at the time of the Helike disaster." "He came up with the theory that earthquakes were the physical product not of the Poseidon's supernatural abilities, but of winds trapped inside the earth." "I know it sounds ridiculous, but he may well have been on the right track." "This area, where Helike once stood, is still very prone to seismic activity." "The last big earthquake struck here in 1995." "The day before, local taverna owner, Kostas Kakavos, noticed something odd in the water." "It's amazing." "The question is, could trapped wind, as Aristotle proposed - or more likely some sort of gas escaping from the ground - actually explain the animals' behaviour?" "Animals acting strangely prior to earthquakes have been witnessed all over the world." "It's thought this might be down to them having more highly tuned senses than us, so they are able to detect the escaping gas, giving them advanced warning of impending danger." "This region of Greece in the North Peloponnese is the most earthquake-prone part of Europe." "It's where Aristotle first made his observations." "And today, geologists working in this area are looking at the connection between gas and earthquakes." "It turns out that trapped gas may well play a role, but not in the way that Aristotle thought." "Gas, particularly carbon dioxide, is naturally produced deep beneath the Earth's surface." "This rises up, getting trapped along fault-lines where the rocks are tightly packed together." "The gas might do one of two things." "As it's under high pressure, it could force its way up between the rocks of the fault, effectively lubricating them so they slip and cause an earthquake." "But most geologists now believe that the rocks of the fault move all by themselves, through seismic activity, and this just allows the gas to escape." "Scientists working here today are looking into the escaping gas as a way to help predict when earthquakes will strike." "Trapped gases may not CAUSE earthquakes, but at least Aristotle's observations were on the right track." "Importantly, he was taking a stab at understanding the world around him from a purely scientific point of view." "He proposed a NATURAL cause for what was otherwise regarded as a supernatural event." "Although Aristotle had made some headway into understanding geological processes, most ancient Greeks still believed that the running of the world - and any catastrophes encountered - lay very much in the lap of their assorted gods." "It was almost 700 years after the catastrophic destruction of Helike before our beliefs on how the world around us worked, really saw a dramatic change." "And it all happened in Italy, during the time of the Romans." "Like the Greeks, the Romans worshipped a barrage of gods." "But religion for the Romans was becoming complicated." "In the decades following the death of Christ, Christianity started to spread through the Empire." "Yet it remained a small and struggling religion practised in secret to avoid persecution." "But all this was about to change." "In early 4th century AD, the Roman beliefs in their assorted pagan gods were to be dramatically overturned." "And it would be a geological event that would do it." "I've come to the Vatican City." "Located in the north of Rome on the west bank of the River Tiber, this country-within-a-city is the focal point of modern-day Italian religion." "The Vatican is the heart of the Holy Roman Catholic Church." "And this area has been home to Popes for over 1,500 years." "It's a place of pilgrimage for Christians from all over the world." "This is St Peter's Square." "And up there, that's St Peter's Church." "One of the holiest places on earth." "That grey building, that's where the Pope lives." "But, you know, it's possible that none of this would be here if it wasn't for at timely sighting in the sky." "1,700 years ago, the Western Roman Empire was on the verge of civil war." "Vying to be sole Emperor were two men" " Marcus Aurelius Maxentuis and this handsome chap, Flavius Valerius "Constantine"." "At the time, Constantine was in charge of the small Roman outpost of Gaul in France." "But he had much grander aspirations, marching his army down to Rome to meet Maxentius." "Eventually, these two wannabe Emperors met and full-scale war broke out." "In October AD 312, they faced each other here at the Milvian Bridge just north of Ancient Rome." "Now, according to a close friend of Constantine, a writer, Eusebius, something miraculous happened in the build-up to the battle." "Something which, arguably, changed the path of Western beliefs for ever." "Constantine's troops were heavily outnumbered." "Knowing the battle would be decisive, he began to pray for divine inspiration." "It was then that Constantine had a vision, described by his writer friend as a blazing light in the heavens which formed the shape of a cross in the sky." "Constantine took the vision as a sign from the Christian God to go into battle." "And more than that, to gain salvation by fighting under the banner of the cross." "The next day, with his troops now bearing Christian insignia," "Constantine faced his rival." "The two great armies clashed." "Maxentius was pushed back towards the Tiber River, to the Milvian Bridge." "Constantine had the crossing covered and inflicted heavy losses." "Among the dead was Maxentius himself." "Victorious, Constantine entered Rome and was proclaimed the emperor of the Western Roman Empire." "He went on to rule for 25 years, always crediting his victory at the Milvian Bridge to the god of the Christians." "Constantine ordered an end to any persecution of Christians within his realm." "Their faith, with its single, omnipotent God, would now become an accepted religion." "Not only that, one that was even practised by the emperor himself." "It was mostly down to Constantine's promotion of the faith that Christianity went on to become so well established in Western culture." "His strength of belief seems to have been firmly rooted in that blazing vision in the sky." "So did Constantine really see a sign from God?" "Or was it something that could be explained by a natural phenomenon?" "If it was down to nature, what could cause such a dazzling vision in the sky?" "Well, a clue to the possible culprit lies in an intriguing Italian legend." "This is the Abruzzi region of central Italy, 150km east of Rome." "In the early centuries AD, a tribe lived around here called the Paeligni Superequan." "Although Christianity was spreading into the area, the tribal people strictly worshipped their pagan gods." "The legend tells of a wild party to celebrate a goddess called Cybele who looked after the harvests." "Now, these festivals were notorious, renowned in polite company for their vulgarity and rudeness." "Men would dress as mythological half-man-half-goat satyrs." "And virgin girls would dance naked around them." "So the legend goes, during the shindig the revellers saw a new star that shone as brightly as the sun." "It got nearer and nearer until the light filled the sky." "The ground shook violently, and the dancers were knocked out cold." "This piece of folklore actually dates from the early 4th century - just when Constantine was going into battle." "So it could provide an explanation for what he saw." "But first, we've got to break down the evidence." "For starters, that light in the sky sounds to me like something falling from space." "The Earth is never short of space debris dropping in unannounced, with anything up to 30,000 tonnes falling on our planet each year." "We see most of this plummeting space rock as shooting stars." "They're not actual stars - that would be ridiculous - but small lumps of rock called meteors." "Meteors completely burn up in the sky due to the massive friction they produce as they go crashing through the gases in our atmosphere." "If a meteor is big enough, it is called a meteorite." "It has the potential to survive the intense burning of the atmosphere, making it all way down to the Earth's surface." "The result - impact." "The interesting thing about meteorites is that they produce a very particular type of dent in the Earth's surface." "Let me show you." "Oof!" "When a meteorite hits the Earth, it produces an explosion on the ground." "This sends out debris in all directions, making a round crater." "Not just that, but the ejected material naturally falls close to the hole." "In 2003, a group of scientists reckoned that this round lake, with its raised rim edges, was caused by the impact of a meteorite, possibly one measuring up to 10 metres across." "This is the Sorrente Regional Park... just across the mountains from where the ancient legend was born." "The scientists discovered that the lake was potentially created some time around the 4th century AD, just when Constantine had his vision from God." "It's an intriguing theory, one that's hotly debated." "Many geologists believe that this crater is no more than a giant ditch dug by 4th-century farmers to provide water for their cattle." "Whether or not this pond is a meteorite crater, it's not hard to see how a falling land of space rock might be taken as a sign from God." "As a large meteorite enters the Earth's atmosphere, it would look like a giant fireball streaking across the sky." "But more than that, when it finally crashes into the Earth the impact has the same explosive power as a small nuclear blast, sending out earth tremors and shockwaves, and creating a mushroom cloud." "Viewed from a distance, a mushroom cloud could be seen as a cross in the sky - which is exactly what Constantine was reported to have seen." "That light in the sky came at a time when Christianity was a struggling religion still trying to merge with the millennia-old doctrine of paganism." "Constantine's vision was possibly the pivotal moment in the Western emergence of a single, monotheistic religion - that of Christianity - which then became the official religion of the Roman Empire." "And it could all have been down to a falling lump of space rock." "From the time of the Romans, Christianity grew and spread." "People still thought catastrophes were driven by divine forces but these events were now believed to be dispatched by just the one and only - Christian - god." "Christianity provided a framework within which the world to be explained." "As far as the Bible was concerned, our planet had been created for mankind by God." "Western scholars were rather unwilling to examine any natural origins of geological phenomenon, as the Bible story of creation was beyond question." "By the 15th century, long after the fall of the Romans, Europe was experiencing the Renaissance." "It was during this time of artistic and intellectual enlightenment that people began struggling to reconcile what the Bible said with what they noticed around them." "The idea was born that perhaps our planet WASN'T shaped by a series of God-driven catastrophes." "But as it was heresy to question God's holy DESIGN, exploration of the MECHANISMS of natural processes still very much remained uncharted territory." "Once again, however, the geology of the Mediterranean would spring a surprise which caused a seismic shift in thinking." "It all kicked off right here in Portugal's capital, Lisbon." "Founded by the Phoenicians nearly 3,000 years ago," "Lisbon has been home to some of the world's greatest explorers." "Over the centuries, the Portuguese nurtured a love affair with the sea." "Lisbon became a flourishing trading centre." "By the 18th century," "Lisbon was the capital of an empire rivalled only by Spain." "Portuguese explorers had travelled the globe, bringing back the riches of the New World and the Orient." "Lisbon was one of the world's great cities, a hugely important centre of power and Western culture." "But in 1755, a catastrophe happened here, one which sent shockwaves throughout Christian Europe." "It was Sunday November 1st, All Saints Day, and the city's churches were packed with worshippers." "Then at 9:30, right in the middle of morning Mass, a huge earthquake struck." "Three massive tremors hit the city in quick succession." "Building in strength and ferocity, their impact on the city was devastating." "The earthquake was so powerful its effects were felt right around Europe and across the Atlantic." "In many of the churches, the roof came crashing down on the heads of those worshipping inside." "Of those who did to make it out onto the streets, many were killed by falling debris." "Devastation swept the city." "If that wasn't enough, a great fire then ravaged the city, taking six days to put out." "The terrible disaster in Lisbon created a crisis of confidence in Christian beliefs." "Why would God destroy his own churches and on All Saints Day, of all days?" "Many people thought the quake was down to the Spanish Inquisition, the Catholic quest to purify the people of Spain by driving out the non-believers." "The Protestants blamed the inquisitors, claiming God was punishing the Catholics for carrying it out." "But hard-line Catholics believed the inquisition had been too SOFT, and that the earthquake was God's punishment for their leniency." "Some people started to look for more earthly explanations for the cause of the disaster." "Even from within the Church, there was mention of a theory that the quake was caused by a sort of contraction of the Earth's crust." "Funnily enough, that's not far from the truth." "But the earthquake was less a CONTRACTION of the Earth's crust and more a movement WITHIN it." "We now know that the crust is made up of tectonic plates." "Like these leaves floating on water, they move around on the Earth's mantle." "We also know that two of those plates, one carrying Africa, and the other Europe, meet off the coast of Portugal." "For millions of years, the African plate has been moving north," "Pushing into the European one." "Over time, the pressure of the plates pressing against each other builds up." "On that fateful Sunday morning in 1755, the two plates slipped, triggering the devastating earthquake." "Measuring almost nine on the Richter scale, the Lisbon earthquake was pretty big." "The eventual death toll was massive." "In all, over 40,000 people perished." "It was the most disastrous quake to strike Europe in recorded history." "More than its physical magnitude, the earthquake created shockwaves in terms of human thinking." "The international nature of the city meant that first hand accounts of the Lisbon earthquake spread rapidly across Europe." "It was the first widely reported international disaster." "The news provoked thinkers across Europe to further challenge the ideas of Christianity." "After the catastrophe struck, the idea gained momentum that the earthquake was indeed a natural phenomenon, and not down to the wrath of God." "The earthquake was a direct assault on the way we believed the world around us worked." "It certainly wasn't an end to our belief in an all-powerful Christian god, but the belief in science was gaining momentum." "New ways of thinking were emerging based on careful observation of the world and testable theories as to how it worked." "One of the fundamental questions was, quite simply, how old is the Earth?" "In the 17th century, an Irish Archbishop called Usher used the Bible to calculate the very moment that the Earth was created." "He came up with the 23rd October 4004 BC." "About midday." "It's very precise(!" ")" "Usher's Bible-based date of Earth's creation was about to be called into question with a challenge inspired by the sights and sounds of an 18th-century holiday ramble." "In the 1700s and 1800s, one of the most popular jaunts for European noblemen was "the grand tour"." "Setting out from all over Europe, the men would go off to learn about the politics, art and culture of the countries around the Med." "Some intrepid tourists also headed off to the surrounding countryside." "One such traveller was a Frenchman by the name of Georges-Louis Leclerc." "He was fascinated by these, the Italian mountains." "He went on to produce over 40 volumes of his observations on the natural world." "One subject which particularly fascinated him was the age of the Earth." "Leclerc didn't look to the Bible to try to calculate the Earth's age." "Instead, he turned scientific method." "Leclerc believed that the Earth was made of material thrown out by the sun." "Amazingly, he quite rightly deduced that our planet originally formed as a ball of molten rock that gradually cooled." "Based on this insightful assumption, he devised an experiment to scientifically calculate the age of the world." "Leclerc wanted to know just how long it would take for a hot lump of iron the size of our planet to cool down." "What he did was he heated up different-sized balls - in his case, made of iron, in my case potatoes." "Then" " I wouldn't try this at home!" " he timed how long it would take for the different-sized balls to be held without burning his fingers." "By measuring the time for the various sized balls to cool," "Leclerc hoped to scale up and calculate the cooling time for a ball the size of our planet." "In 1778, three years after the Lisbon earthquake, he came up with a new, scientifically derived age for the world." "From his experiments, Leclerc estimated that the Earth was around 75,000 years old." "I can tell you now, he was some way out." "Scientists currently reckon that our planet is 4½ BILLION years old." "But that's not the point." "At least he was heading in the right direction, proposing an age for the Earth that was far older than the 6,000 years calculated by Bishop Usher." "However flawed him technique might have been, using scientific method, Leclerc cast doubt on the traditional interpretation of the Bible." "The age of the Earth wasn't the only challenge taken up by the emerging scientists." "They also wanted to get a handle on the underlying natural processes that had shaped the planet, and the length of time that it took those processes to run their course." "The Bible, as you might expect, had its own answers." "A fundamental Old Testament belief was that a single, global catastrophe had shaped the landscape of the world as we know it." "That was the "Great Flood"." "According to the Bible," "God was so angry how wicked people on earth had become that he decided to wipe the slate clean." "He chose to send a cataclysmic flood to kill off everything and start all over again." "For 40 days, the rains came down." "The oceans rose and water covered the entire Earth." "Only the occupants of Noah's Ark were kept safe and dry." "Interestingly, Christian thinkers tried to reconcile the Biblical accounts of the Great Flood with features they saw in the landscape." "And you know what?" "It seemed to fit." "Imagine this pile of sand is the surface of the Earth just prior to the Great Flood." "Look what happens when I drench it in a deluge of floodwater." "The surface contours change quite drastically." "The landscape itself has been sculpted and shaped by the receding waters, producing everything... from cliffs and gorges..." "to hills and valleys." "Those who took the Bible literally believed that such a cataclysmic flood had indeed shaped the Earth's surface." "But scientists, who were themselves mostly Christians, began to challenge this belief." "They held the opinion that God had created nature which was then governed by its own set of rules." "They argued that the Great Flood itself was not physically possible, as our planet simply didn't have enough water." "Questions were also raised by these, the fossils." "Fossils had been unearthed all over the world, from the tops of mountains to the seashore." "The familiar shapes of these odd lumps of rock had intrigued curious minds for millennia." "From the time of Aristotle, the idea had been knocking around that fossils were potentially the remains of once-living organisms." "Christian doctrine could accommodate this notion., proposing that fossils had been laid down by the waters of the Flood." "Not a bad explanation..." "if all fossils are found on the very surface of rocks." "But they're not." "The reality that fossils were mostly found deep down WITHIN rock posed a problem." "But in 1815, an English surveyor called William Smith provided an explanation." "He had long been studying rock strata, noting the different fossils he'd unearthed within the different rock layers." "Smith concluded that fossils really were the ancient remains of plants and animals but, more importantly, that these organisms had been trapped within the different rock layers at a time when the rocks themselves were being formed." "And he was absolutely right." "We now know that fossilisation can't just happen anywhere, but requires a set of specific geological processes to occur." "For fossils to form, an animal must have some hard body parts like bones or a shell... just like this." "Then it would be really helpful if, when the organism dies, it lies down in an area where silt is being rapidly deposited, such as a shallow lagoon fed by a river... just like this." "OK, we've got our animal." "It's died, poor thing." "It's fallen down, and it's going to settle on the bed of a shallow sea." "Now the rivers wash in mud, sand and silt." "The sediment comes piling in, gets built up over hundreds, thousands, even millions of years." "Until the weight of what is on top transforms the sediment, with animal remains trapped inside, into rock." "And when you break open that rock you find fossils." "Although the animal's remains are now made of rock, it still retains the original shape of the ancient creature." "It was now understood that fossils were created over vast periods of time during the formation of the very rocks themselves." "But "Strata" Smith, as he was nicknamed, didn't stop there." "It was originally thought that all the layers you can see in a rock face like this were laid down in one go by the waters of the flood." "But with his understanding of fossils, Smith was able to show that the layers in the rock strata had been laid down at very different times in Earth's history." "Fossils provided a tool for seeing how the Earth had changed over time, with the oldest at the bottom and the youngest at the top." "It was becoming apparent that the Earth's natural geological processes stretch back possibly millions of years." "So, thanks to geology radically changing our beliefs, another quantum leap was made in our understanding of how the world around us works." "While Smith had the help of million-year-old fossils, one of MY forbears, a Scottish geologist called Charles Lyell, had some modern-day creatures to thank for his discoveries." "He came here to Naples in Italy in 1845, having set off on his own grand tour of Europe." "Charles Lyell arrived in the Mediterranean filled with the new ideas that geological processes could take very long periods of time." "His great discovery was that the same processes were still going on today." "Just outside Naples in the town of Pozzuoli," "Lyell came across some impressive ancient Roman ruins." "This is the temple of Serapis, built in the first century AD." "It's not actually a temple, as such, more a Roman marketplace." "One of the things that struck Lyell about this place was these three huge marble columns and the fact that they have strange, dark bands around the middle." "When he got up close, he discovered that amongst all this black stuff there were hundreds of tiny holes." "And in some of them, there were shells." "Lyell recognised that the holes were identical to those he'd seen along the shoreline of the Med." "These had been carved out by a rock-chomping mollusc called Lithophaga, which literally means "rock eater"." "Lyell believed the only way marine molluscs could've damaged the columns was if the columns had at one time been submerged underwater only to reappear again out of the sea." "He deduced that this could be the result of two different geological processes." "Either the level of the sea had risen up to flood the temple and then fallen again or the land that the temple stands on had somehow sunk down and been submerged and then pushed back up." "Either way, the boreholes in the marble columns were physical evidence of a rapidly changing geological environment." "Something pretty substantial had occurred here in the time since the temple itself was built." "Lyell had the amazing revelation that geological processes could actually be witnessed going on today." "Here at Serapis, those processes were happening right beneath his feet." "Lyell wasn't exactly sure about the underlying cause of the changes." "But he did know that the level of the Med had not changed significantly since Roman times." "So the answer must have been in the movement of the land itself." "One obvious culprit was volcanic activity which this region of Italy is home to due a series of cracks that formed deep underground around 7 million years ago." "The cracks allow molten rock, called magma, to rise up from the Earth's mantle." "It can then accumulate and expand underneath the surface, producing something called a magma chamber." "Magma has the potential to erupt through the crust." "But it's not always destined to break through the Earth's surface." "Sometimes magma just builds up underground." "It's a bit like blowing up a balloon." "As the molten rock rises up from below... it inflates this magma chamber, causing the land surface above to be pushed up." "It was on that elevated land that the Romans built the Temple of Serapis." "For the temple to sink beneath the the waves, the reverse must've happened." "The magma would've been drawn out of its underground chamber back down to greater depths." "This deflation caused the land to drop and our temple to drown." "A fresh accumulation of magma some time in the last 1,500 years once again pushed the ground up." "Returning the temple with its mollusc-bored columns to where it is today." "Although the changes at Serapis had happened quite recently in geological time," "Lyell believed the same underlying processes had been going on, unrelenting and with the same intensity, for millions of years." "If, in a 1,000 years are so, the land could be raised a few metres or feet then, over a million years, the same process...could make a mountain." "This idea came to be called - and it's a bit of a mouthful - Uniformitarianism." "And this was to become the foundation stone of modern geological thought." "So we owe an awful lot to those munching molluscs." "By the middle of the 19th century, our understanding of how the world around us worked had a firm scientific foothold." "Solid evidence now existed suggesting that geological processes stretched over millions of years." "But scientists weren't exactly sure why." "A clue to this problem came in 1914, from a brilliant German scientist called Alfred Wegener." "What Wegener suggested was so radical that it prompted one American scientist to say," ""If we are to believe this hypothesis," ""we must forget everything we have learned in the last 70 years and start again."" "You see, Wegener had proposed a fundamental geological process which, amongst other things, explained why the landscape changed so very slowly." "It all came to him in the form of a giant jigsaw puzzle." "He was intrigued that identical animal fossils had been discovered on opposite sides of the Atlantic Ocean." "At the time, it was thought that animals had migrated from one continent to another over huge land bridges which had then sunk into the sea." "Wegener came up with a completely different theory, getting his inspiration from the shapes of the continents." "Wegener proposed that at some point in Earth history, all the different continents that we see today had fitted together like a giant jigsaw." "He called that single, vast supercontinent Pangaea," "Greek for "all Earth"." "But this enormous land-mass wasn't destined to stay like this forever." "Wegener believed that over time Pangaea split up, and that various continental land-masses drifted apart." "It all started here in the central part, where it broke away creating a new ocean, the Atlantic." "Then the split went to the south, creating the southern Atlantic and pushing South America away from Africa." "South America continued on its way, finishing up there." "Meanwhile... ..the rest of the southern continents headed eastwards across to here." "Africa split off, heading this way." "Then they all split up!" "Antarctica went that way," "India headed northwards, and Australia went over there." "Then the split went into the North Atlantic and North America headed westwards and ended up way over here." "Meanwhile, Europe spread eastwards..." "Ended up over there." "The movement of the continents to the positions they occupy today was the result of what Wegener called "continental drift"." "It may seem incredible that continental land-masses can move such massive distances across the globe." "But it took 250 million years for the continents to get to where they are today." "That's because they move at about 15mm, half an inch, a year." "That's the rate your fingernails grow." "Geology, it seems, just needs time." "Thanks to the likes of Wegener, Lyell, Smith, and Leclerc, by the middle of the 20th century, our understanding of how the world around us worked had come a long way." "When I was a kid in the late 1960s, geologists believed that the Earth was very old, that geological processes stretched over hundreds of millions of years and that the slow movement of the continental land-masses was crucial in shaping the landscape." "You could be forgiven for thinking that we'd got our planet cracked." "But geology is full of surprises." "Just when one set of ideas and beliefs establishes itself, something big happens that forces us to think again." "This is the Medieval village of Gubbio, tucked away in the heart of the Umbrian countryside of central Italy." "It was here in this quiet hilltop town that the idea of geological processes ALWAYS taking millions of years was dealt a catastrophic blow." "In the late 1970s, a Californian scientist called Walter Alvarez was doing fieldwork based around here." "He was studying the local limestone to see what it could reveal about environmental changes during the last 100 million years." "Just up the road from here, in the Bottaccione Gorge," "Alvarez found an intriguing formation in the rock face that would once again seriously upset our understanding of how the world works." "And this is it, a natural wall of limestone with a thin layer of red clay in the middle." "Not much to look at but, by knowing the age of the surrounding rock," "Alvarez knew that this thin layer of clay separated two important periods of geological time." "This limestone below formed during a time called the Cretaceous." "This limestone above comes from the period immediately after, called the Tertiary." "Now, the clay layer in between - you can just see it there - that is a dividing line known as the "KT boundary"." "It dates from one of the most significant episodes in our planet's history." "It was at that point in time, 65 million years ago, that well over 75% of life on Earth, including the dinosaurs, died out." "Alvarez believed this line of clay might hold the key to unlocking the cause of the global mass extinction." "He sent a sample of the clay off to his dad, who just happened to be a Nobel Prize-winning physicist." "Now, when Alvarez Snr analysed it he discovered a surprising geological anomaly." "The clay layer contained 30 times the expected level of a rare element called iridium." "There are several theories as to how you can get so much of an element like iridium in one thin layer." "But the most convincing is that it has to have fallen from space." "Iridium is found within meteorites and their larger cousins the asteroids in very high levels, up to 1,000 times higher than occurs naturally in the Earth's crust." "To discover such a high concentration within a sample of clay set alarm bells ringing." "Prompted by the father and son discovery, samples from KT boundary sites all over the world were re-analysed." "Everywhere from Denmark to Australia, the different sites all showed exceptionally high amounts of that special element, iridium." "It appeared there was an iridium-rich layer coating the entire planet right at the time of the KT boundary." "Alvarez suggested that this global anomaly was the result of an asteroid striking the earth." "Scientists knew that our planet has always been struck by space debris." "But the possibility that a single impact wiped out 75% of the world's animal and plant species came as a bit of a shock." "According to the thinking of the early 1970s, the mass extinction at the end of the Cretaceous should've occurred over MILLIONS of years, following very slow, very gradual, geological processes - not an event that happened overnight." "But the discovery of high levels of iridium in the KT boundary suggested a new, cataclysmic scenario." "It was proposed that a huge asteroid some 10km in diameter had struck the Earth, possibly in the Yucatan Peninsula in modern-day Mexico." "The impact produced an explosion of gigantic proportions." "Equivalent to 100 million megatons of TNT or one billion times the Hiroshima atom bomb." "Dust and rock particles were sent high into the atmosphere, spreading right across the globe." "Forest fires ravaged the planet, sending up a thick layer of soot." "The world would've become cold, blanketed in an eerie darkness." "With sunlight blocked out, plant life would have died off... followed by the animals." "The only remaining survivors would have been those opportunists able to adapt to such horrendous living conditions, barely existing on what was left." "The discovery that the mass extinction at the KT boundary was probably caused by a single, catastrophic event provoked yet another giant leap in our understanding of how our planet really works." "For nearly two centuries, the consensus was that all geological processes occurred slowly, over millions of years." "Yet here was evidence that a single catastrophic event had changed our planet quite literally in a flash." "From the beliefs of the ancient civilisations to the emergence of modern scientific thought, over the last 2000 years we have experienced some dramatic changes in the way we view our planet." "Our current understanding is that both gradual processes and catastrophic events together dictate how the world around us works." "Throughout history, the geology of the Mediterranean has inspired our beliefs." "Yet, following new discoveries, our understanding of the world is constantly being challenged." "Today's scientific facts may yet prove to be fiction, and it'd be wrong to think we've got geology cracked." "In many respects, the planet we live on remains a mystery." "For further information on Open University programmes, go to..." "Every year, millions of us flock to the Mediterranean." "The sun, sea and sand make it a perfect place to relax." "But the Med is also the birthplace of many great civilisations, whose survival depended on the geological forces around them." "For thousands of years, civilisations have been locked in a never-ending war in which countless battles have claimed many lives and victories have only been won through great skill and ingenuity." "I'm not talking about battles with fellow humans," "I'm talking about a fight against a much trickier opponent - water." "Because water is so crucial to us, the really successful civilisations are the ones who've learnt to best exploit it." "Through the ages, civilisations have had to rise to the challenges presented by water." "I'm going to travel to Turkey to discover whether its stone-age inhabitants survived one of the biggest floods in human history." "To Greece, where a simple rock solves the mystery of a stranded civilisation." "And I'll reveal how water helped bring the greatest empire in the ancient world to its knees." "As a geologist, I'll tell you a story of the Mediterranean that you won't hear from the tour guide." "I'll show you that, whether we control water or water controls us, it's all down to what's beneath our feet." "The rocks." "Around 8000 years ago, water brought catastrophe to this area of Turkey." "I'm going to discover whether the stone-age people who lived here managed to survive it." "This is Kilyos Beach on the Black Sea coast of Turkey." "It's about an hour's drive north of Istanbul, and it's a favourite summer getaway for those escaping the city." "The evidence that a disaster of biblical proportions took place here lies deep down in the murky depths." "150 metres below sea level, there are remains of what was once an ancient coastline." "What's a coastline doing down there?" "You don't have to be a geologist to realise the sea level was once much lower than it is today." "At the end of the last Ice Age, this 1000-kilometre long Black Sea was nothing more than just an isolated lake." "Around its shorelines were the settlements and hunting grounds of our stone-age ancestors." "So what happened to the people who lived here?" "To find out we have to turn to a massive, mind-boggling natural machine - the water cycle." "Over a period of 3000 years, a volume of water equivalent to all the oceans falls on our planet." "The movement of this water around the globe is known as the water cycle." "Water evaporates from the oceans and passes into the atmosphere." "It makes its way back down when it falls as rain or snow." "Huge quantities of water fall on the north and south poles, adding to the ice already there." "The polar ice sheets grow, taking up more and more water." "As the ice builds up, sea levels go down." "But when temperatures begin to rise, the opposite happens." "Melted water from the ice runs down to the oceans and the water levels begin to rise." "That's exactly what was happening 10,000 years ago." "It eventually gave us the Mediterranean coastline we know today." "The Med stretches from the Straits of Gibraltar in the west, across Spain, Greece and Turkey, to the shores of Israel in the Middle East." "To the north is mainland Europe and to the south, the continent of Africa." "And just to the north-east of the Mediterranean is the Black Sea." "It's when the waters rose to create this coastline that disaster struck what is now northern Turkey." "I'm going to use this local food to show you what I mean." "Here is the Mediterranean." "This is the Middle East, here's North Africa." "That is the Straits of Gibraltar and here is Europe." "The Med was gradually expanding as a rise in oceans fed more and more water into it." "It rose 120 metres - over 400 feet." "Over here, to the north-east of the Med, was a freshwater lake." "At first, the people who lived around the shores of the lake wouldn't have worried about the rise in Mediterranean waters." "That's because the sea was safely held back by a land bridge, which acted like a giant dam." "The land bridge crossed where Istanbul and Bosphorus are today." "But the sea can only be held back for so long." "Inevitably, about 8,000 years ago, the waters spilled over the land bridge." "The whole area was engulfed by the salty Mediterranean waters and the original shoreline was drowned." "By 6,000 years ago, the small freshwater lake had become the Black Sea that we know today." "All this flooding was pretty bad news for those who lived along the old lake shore." "This was one of the biggest natural disasters in human history." "Did the Stone-Age people who lived here manage to survive?" "The evidence suggests that many of them did." "They even journeyed across Europe and as far away as Asia." "The clues can be found in our language." "BABBLE OF VOICES" "Some linguists believe that many modern languages throughout Europe and western Asia are related, and can be traced back to those Stone-Age travellers." "Take the word "father", for example." "Do you know the word for father in Turkish?" "Father?" "Baba?" "Baba." "Is that the only word you have, baba?" "Peder." "What's that?" "Peder." "Peder?" "Peder." "I want to know the word for father in Portuguese." "Pai." "Pai?" "In English, father, in French..." "Pere." "Pere." "Papa." "And what is your language?" "Hindi." "In Hindi it's papa." "Papa." "The Spanish for father?" "The word father." "Padre." "Padre." "Padre - of course." "Padre." "So in European languages we've got padre, we've got pai." "We've got vater, we've got pere." "In Turkish we've got baba or peder." "And in Asian languages it's the same, too." "In Sanskrit we've got pitar, in Hindi we've got baba." "The reason is all of these words originated from the same source." "It looks like the source of those words was right here - the Black Sea." "8,000 years ago, when the inhabitants fled their homelands to escape the Great Flood, they took their language with them." "However fast the flooding of the Black Sea may have been, it seems that there were many who managed to get away in time." "As the planet warmed up and sea levels rose, not everyone was able to escape the rising oceans by land." "Some people were stranded, surrounded by water." "Taking a cruise on the Aegean Sea is a popular way for holidaymakers to travel around the Greek islands and absorb the sights." "The tourists who flock to Greece every year have over 1,000 islands to choose from." "But many of these islands wouldn't be here at all if it hadn't been for those rising waters." "If you had been here 10,000 years ago, you'd have been hiking." "That's because these apparently far-flung islands were a collection of larger land masses." "The area of the Aegean stretched between what is now mainland Greece and the west coast of Turkey." "People lived and farmed here." "But as Mediterranean waters rose, the area started to flood." "People were forced to move to higher land." "What were once peaks on large land masses were transformed into islands." "Our Stone-Age ancestors gradually became marooned on their islands." "To make matters worse, many found themselves with limited resources." "This isolation could spell disaster, if not total extinction." "The only way for the islanders to survive was to take to the seas." "The mystery of whether they managed to achieve this can be solved by geology." "A major clue is this rock." "It's called obsidian and it's from this island, Milos, in the Aegean." "Obsidian is a clue because there's a special quality which is all down to how it formed in the first place." "To find out how it got here I'm going to travel back 15 million years." "15 million years ago, just as now, the whole of the Earth's surface was a series of moving plates." "In this region, the African plate was moving north towards the European plate." "Imagine that strip of rock over there is the African plate." "And imagine that one over there is the European one." "Stuck in the middle was the Tethys ocean, destined to become the Mediterranean." "The African plate was moving really fast - roughly at the rate my fingernails grow." "You may think that's slow, but in geological time that's motoring along." "As the plates collided, the African one was pushed deep down beneath the European one, dragging part of the Tethys ocean floor behind it." "As it descended, wet rocks were taken down into the depths." "Over a few million years, water in the rocks was carried to deeper, hotter parts of the Earth's interior until heat and pressure forced the rock to melt." "This melted rock, or magma, was pushed upwards through faults in the crust of the overlying European plate to become volcanos." "That's how the volcanic island of Milos was formed five million years ago." "The same process also created the massive deposits of obsidian here." "It's what the islanders did with this rock that solves the mystery of whether they managed to set to sea." "You can still find obsidian on Milos." "In fact, here it's absolutely everywhere." "All these black pebbles are obsidian." "But what I want to find is the actual rock that fragments like this came from." "And here it is." "This is an ancient lava flow and it's stuffed full of obsidian." "There's a big lump." "Here's another piece - there's absolutely loads of it." "Obsidian is like a volcanic glass which is formed when molten lava like this once was cools really quickly." "So quickly, in fact, that crystals don't have time to form." "Because it's got no real crystals, it doesn't have a regular structure." "And that means it's easy to cut into smooth, sharp edges." "This characteristic of obsidian made it ideal as a versatile tool." "Stone-Age implements made from obsidian have been found at archaeological sites across the Aegean and on mainland Greece." "Our stone-age ancestors used obsidian for arrowheads and knives, as well as for carving wood and bone tools." "It was also good for digging, and that made it really useful for farmers." "Obsidian also helps in our quest to find out what happened to the people stuck on their islands." "It's a very revealing rock." "It has a unique geological fingerprint, so it's easy to trace where it came from." "All the Stone-Age obsidian tools found around the Aegean have been traced back to Milos." "Obsidian was one of the most sought-after items in the ancient world." "It provides the earliest evidence of transport of goods by sea." "Thanks to obsidian and some clever geological detective work, we now know that our Stone-Age ancestors were able to move off their islands." "They not only survived, but traded and thrived." "Travel by sea in the Mediterranean had begun in earnest." "As the Stone Age passed into the Bronze Age, the need to travel further across the seas continued to challenge those living in the region." "A new Mediterranean civilisation was about to rise to this challenge, leaving us with a navigational mystery." "Our story begins in Egypt, where a Greek-speaking people from Crete called the Minoans have given us a puzzle to solve." "Wall paintings in tombs at Thebes show Minoan figures and their wares." "What's more, fragments of paintings created by the Minoans themselves have also been found in Egypt, suggesting they actually settled and lived here." "Egypt is nearly 1,000 kilometres from the Minoans' home in Crete." "So how did they manage to get here?" "In 1500 BC, successfully navigating the Mediterranean across open water would have been a monumental and hazardous journey." "The answer lies in the Minoans' skilful use of the wind." "The Minoans realised that they could use the wind for more than just powering their sails." "They could also use it for navigation." "It was their understanding of how the Aegean winds worked that enabled them to set sail across open waters and head directly for Egypt with no visual points of reference." "The winds from the Aegean to Egypt are mainly north-westerlies." "In other words, in order to get to Egypt, all the Minoans had to do was follow the winds and they would take them to the south-east." "By using their knowledge of the winds to navigate, the Minoans had kick-started a new era in sea travel." "By 1000 BC, a new seafaring civilisation had managed to go one better." "I'm going to show you what they came up with." "The Phoenicians were originally from Lebanon, and they travelled further than any of their predecessors, using a revolutionary method of navigation." "The Phoenicians steered by the stars in the sky." "Especially the Pole Star - the only one that hardly ever changes its position." "And that's because the Earth's axis of rotation points almost exactly towards it." "Using the stars to navigate, the Phoenicians were the first to trace routes to the western Mediterranean, and towards the Atlantic coasts of Africa and Europe." "Their navigational skills helped the Phoenicians control trade and as a consequence, they became one of the major players in the Mediterranean for hundreds of years." "Just like the Phoenicians, the Greeks who followed were also determined to master the Med and create a trading empire." "They introduced another heavenly body as a navigational tool." "During the day of course, there weren't any convenient stars to use, but by 330 BC the Greeks had started to navigate using the sun." "This is how they did it." "If I stand a straw on its end, it casts a shadow." "The length of the shadow it casts at midday gives me my latitude - in other words, how far north or south of the equator I am." "If I go towards the equator, the length of the shadows gets less because the sun is directly overhead." "But if I go northwards, away from the equator, the length of the shadow gets bigger because the sun is lower in the sky." "This was a principle that the early sailors used to estimate the latitude." "Of course they probably didn't use straws." "Eventually instruments would develop that gave more precise measurements but which still relied on the sun's shadow." "Impressively simple, but navigating by the sun and stars had one major drawback." "The weather." "In winter, the Mediterranean can be just as bad as in Scotland." "It's cold, wet, but more importantly, grey." "If you've got clouds and you can't see the sky, you can't see the sun and the stars." "In other words, you can't navigate and if you can't navigate, you can't trade." "The solution lay deep down in the centre of the Earth." "If you imagine this peach is the Earth, then the skin is the crust." "I'm sitting on it here." "If I dig down a few tens of kilometres or miles then I get to the mantle which is this orange stuff here." "If I dig even deeper than I get down to the core, the peach stone." "The thing about the core is that the outer part is a fluid mixture of sulphur and iron." "This iron-rich fluid is sloshing around with the rotation of the Earth." "Because that iron is moving, it creates electric current." "This circulating current generates a magnetic field that is lined up north-south within the earth, just like a giant bar magnet." "The magnetic fields pop out the south of the planet, travel all the way round and pop back in in the north of the planet." "It was thanks to these magnetic fields that a new instrument was developed, which gave mariners an even greater command of the seas." "The compass." "And to make a compass, you needed a very special rock." "Remember the collision between the African plate and the European one that caused a crust to crumple?" "Well, that exposed this stuff at the surface - magnetite." "Magnetite is a mineral containing iron oxide which naturally aligns itself north-south with the Earth's magnetic field." "By the 12th century, the idea of the magnetic compass had been brought to Europe by Arab traders, probably from China." "These early compasses were very primitive." "Let me show you." "Sailors would rub an iron needle against a lump of magnetite to magnetise it." "Then, they would float it in a bowl of water and the needle would align itself, north-south." "Even though the compass wasn't entirely accurate, for early sailors, knowing even the rough position of the north was a big deal in letting them explore." "Having been flooded and stranded by the rising Mediterranean, over thousands of years sailors had developed increasingly sophisticated navigational skills, and introduced instruments like the compass." "They had finally learned to master the challenge of the seas." "Water also presented our ancestors with challenges on land." "To meet these, they first had to understand nature's remarkable plumbing system." "It would take all the ingenuity of the ancient Greeks to figure it out." "It is here in the Peloponnese region of mainland Greece that the ancients used their knowledge of geology to save the land from flooding and defeat their enemies." "Here, the summers are long and hot, and rain tends to appear only in the winter." "For the ancient Greeks, survival depended on freshwater springs like these." "The springs were their life blood, providing water all year round, even in the dry summer months." "The source of these springs lies many kilometres away, up in the mountains, where geology provided the Greeks with its very own water storage and plumbing system." "Here, in a labyrinth of caves and tunnels, we can see how it all works, thanks to a very useful rock." "Wow!" "Look at these wonderful cave rocks." "We've got our stalactites and stalagmites." "Remember, the 'tites come down and the 'mites go up." "We've got these curtains of rock along the back here." "We've got these sheets called flowstone and all of this is just from water that is percolating through, carrying dissolved limestone and then when it comes out into the cave, it deposits it." "These are unbelievable." "These rocks are made from limestone." "Around 100 million years ago, this limestone was actually the ocean bed." "It's made from the body parts of billions of tiny, spineless sea creatures, squashed and compacted together." "The collision of Africa into Europe squeezed these rocks up out of the ocean." "As a result, most of the Mediterranean sea is now surrounded by limestone, which has proved to be a bit of a life-saver." "Over a cup of coffee and a slice of cake" "I'm going to show you how this natural water storage system works." "Because it's porous, limestone is able to capture water falling as rain." "Imagine this sponge cake is a layer of porous limestone." "When it rains - I am going to use coffee - the rain permeates into the limestone." "Gravity drags it down through the rock until it hits an impermeable non-porous layer beneath, in this case the plate." "The limestone rocks act as a natural storage system, absorbing and then releasing the rain water over a long period of time." "Eventually this water emerges many miles away as freshwater springs." "The ancient Greeks were about to uncover the route the water took from the limestone hills to the distant springs." "This knowledge would eventually save them from a watery disaster." "The clue to discovering how the water travelled from the hills to the springs lay on the plains." "Here the Greeks found a series of holes in the ground, known as sinkholes." "They're formed by rain water flowing over limestone rock." "When the water finds a crack in the rock, it starts to slowly dissolve it." "Over time, more and more of the limestone is eaten away and the crack gets bigger and bigger, eventually creating a sinkhole like this." "The Greeks wanted to know where these sinkholes led, so they devised a simple but brilliant experiment." "To find out where the waters of a particular sinkhole went, the ancient Greeks used these - pine cones." "Down below me is where that pine cone would have come out if I'd had the patience to wait for a few weeks." "The sinkholes I've just been to are about 25 miles, 40 kilometres over in that direction." "The water in those sinkholes has flowed down through underground channels that have carried them below the limestone mountain and out into these freshwater springs at Kaveri on the shores of the Gulf of Argos." "The pine cone experiment had shown the Ancient Greeks the route the water took from the limestone mountains to the springs at the coast." "Now they had a basic geological understanding of the underground water network." "This new-found knowledge was about to come to the rescue." "The climate of the Mediterranean has changed little since ancient times." "Through the long hot summer months, the Mediterranean is dry and parched." "When, after months of drought the weather finally changes, the rain is a godsend, replenishing both the land and the springs." "But in ancient Greece, the rain could also bring destruction." "When winter storms threatened to flood the plains where they lived and farmed, the Greeks used the sinkholes to avert disaster." "To get rid of that floodwater, they built drainage channels like this down to the sinkhole." "I'm walking in a giant gutter." "By diverting the floodwater to the sinkholes, it drained safely away to distant springs." "For the people of the plane, sinkholes were a gift from geology." "Unfortunately they could also be a gift to their enemies." "This is all that remains of the ancient Greek city of Mantinea," "125 kilometres west of Athens." "In 418 BC, this was the site of the largest land battle of the Peloponnesian wars." "The Mantineans with their allies were fighting their neighbours, the Spartans." "I'm about to show you an action replay." "And here it is, in miniature at least." "Here is the city of Mantinea and here up on the hills are the Mantineans and their allies." "Down on the plain are the Spartans, 4,000 men led by their king, Agis." "Agis and his Spartan army advanced to within a javelin's throw of the Mantineans." "But the Mantineans have the advantage of height up on those hills." "Things aren't looking good for the Spartans." "Suddenly, Agis orders his army to withdraw." "He has come up with a cunning plan." "He's going to use geology to win the battle." "There were several major sinkholes on the Mantinean plain and the wily King Agis knew these were crucial to the Mantineans because they provided drainage during heavy rainfall." "Agis realised that the autumn rains were imminent so he decided to block the downstream end of this river." "That would cause the river to flood over the land-locked plains and the sinkholes wouldn't be able to cope with the amount of water." "The blocked river flowed onto the plain." "Together with the impending autumn rains, the volume of water would be too much for the sinkholes and they would overflow." "The Mantineans couldn't just stay up in the hills and watch their city and farmland flood, so they came down to the plain and lost their height advantage." "It was just what Agis wanted, and he moved in for the attack." "King Agis's tactics worked brilliantly." "I'll spare you the details of the battle that followed - suffice to say the Mantineans were defeated." "The ancient Greeks had used their knowledge of geology to control water and even conquer their enemies on the battlefield." "Back in the cities, water management was also a major issue." "Citizens were demanding water for both sanitation and recreation and the Greeks responded with their trademark ingenuity." "Established in 700 BC, Corinth was a major Greek city state which gained much of its power from its commanding position." "It ruled two gulfs, two ports and the land bridge linking Athens to the Peloponnese." "But the jewel in its crown was water." "Ancient Corinth wouldn't have been here if it wasn't for an abundance of natural springs." "In Greek times, it was known as the well-watered city and there were something like 20 springs." "The biggest and most important was here - the Pierian spring." "Its position determined the location of the baths, the agora or marketplace, even the houses of the elite." "The rain that falls on the slopes above, trickles down through these limestone pebbles until it meets rock that it can't get through." "The water then flows down along the rock until it gets to the spring." "Not satisfied with the capacity of the natural water channels, the Greeks carved out much larger ones, like this." "They put in a whole new plumbing system." "Later, when the Romans arrived in 146 BC, they took Greek plumbing to new heights." "This was a Roman fountain house." "Fresh spring water would have been constantly spouting out of these holes." "Corinthians would collect the water in their amphora, or jugs, and take it away for drinking." "The uncollected water would flow away in these channels down to the street." "The spring water would have flowed along the edge of the main street of ancient Corinth." "Here, there would have been a line of shops and shoppers would have bent down, dabbed their sweaty brow and had a little drink." "These weren't sewers or drains - they were over here, below the main road." "They were about this size - this was plumbing at its most sophisticated." "And what was flowing through the drains, well, that was over here." "Welcome to the toilets at ancient Corinth." "The Romans would have sat around here, chatting to their friends and doing their business through the holes below." "When they finished they would wash their hands in the water flowing along this channel and their business would be flushed out along here." "Convenient and very public." "Knowing that their wealth and power depended on it, water inspired the Romans to innovate, pushing them to new technological heights." "The more technologically advanced and sophisticated civilisations became, the more they battled to control water." "Often they battled in vain, and the ingenious Romans were no exception." "The Romans were ambitious." "They knew if they mastered the Mediterranean trade routes, they would secure the dominance of their empire." "The key to their strategy was to take possession of major sea ports and in the eastern Mediterranean, the most important seaport of all was Ephesus." "In 133 BC, the Romans took control of Ephesus on the west coast of Turkey." "But within 600 years, Ephesus had become a ghost town." "In its heyday, Ephesus was one of the largest cities in the Empire and a quarter of a million people lived here." "It was a thriving port, bustling with life, but after centuries of commercial and cultural dominance, Ephesus was abandoned." "So what happened to this magnificent city?" "Ladies and gentlemen, right here, you all can see..." "Today, as one of Turkey's most popular attractions, the only people you will find in Ephesus are tourists." "I'm going to find out how much they've learned." "Here at this spot we can see two different buildings together." "Why did the Romans leave this beautiful city?" "You haven't told us that." "Why did the Romans leave the city?" "He is the guide, he knows." "We haven't got round to that yet." "We are trying to find out why this city became abandoned." "Because of the mosquitoes." "I don't have a clue." "You don't have a clue!" "I'm very sorry." "The river silted up so it was no longer a harbour." "Why did the Romans leave?" "I have no idea." "No idea?" "They had a lot of problems with the river Maeander, silting up the harbour." "Because of malaria." "Because of malaria." "It was too hot!" "Once they were done with their shopping." "Cleopatra came a couple of times and went shopping." "The shops are lousy, aren't they?" "Yes, they're lousy and it's too hot." "The bathroom smells." "You just get tired of these things and move on." "I think you've just started a new theory." "It used to be a port and the sea dried up and maybe that's what it was." "Well, it looks like some people have been paying attention." "The reason for the fall of Ephesus lies in the silting up of the harbour." "This is the road leading to the ancient harbour at Ephesus, its gateway to the rest of the world." "Every day, huge amounts of vital goods would come down this way to the harbour, out to sea, bound for Rome and the Empire." "Does anyone speak English?" "I'm looking for the sea." "Is this the road to the sea?" "The sea?" "The sea?" "This way?" "This way." "How far?" "This way, just here?" "OK." "I've been walking for half an hour now and still no sign of the sea." "I should have reached the harbour ages ago - instead, all I've seen are fields and this." "Swamp." "This is where the harbour should be but there is no port, no coastline." "Just acres of marshy swampland." "The story of what happened to the harbour all started with a change in the weather." "Around the time the Romans arrived in Ephesus, the planet was undergoing climate change." "The Mediterranean area was becoming warmer and wetter." "Ephesus had fertile river valleys, which were ideal for farming." "Coupled with its easy access to the sea," "Ephesus soon became a bread basket for Rome." "But as the Roman Empire grew, so did its appetite." "More farmland was needed." "Seizing their chance to improve on what nature had given them, the Romans cleared massive areas of forest to make way for more crops." "This was a huge mistake and was going to cut off Ephesus from the sea forever." "To understand why, I need to go to the mountains." "This is what I have come into the mountains to find - the source of the Kucuk Menderes river known to the Romans as the Cayster river, which flows 95 kilometres in that direction, all the way down to Ephesus." "These mountains were among those formed 50 million years ago when Africa collided into Europe and pushed up the floor of the ocean." "As the ground rose, this river, which once meandered gently down to the sea, was raised higher above sea-level." "The higher a river is above sea level, the more power it has, and this one became a raging torrent." "But it wasn't going to stay that way forever." "By around 6,000 years ago, thanks to melting ice sheets, the Mediterranean Sea rose by 120 metres." "That's nearly 400 feet." "That meant that rivers weren't as high above sea level as before." "As a result, they lost some of their energy." "They slowed down." "It was this slowing down of the rivers that was to ultimately prove disastrous for the Ephesians." "By cutting down trees, the Romans had meddled with nature." "The trees had performed a vital function of binding the soil together." "With the increased rainfall no longer broken by the forest, water hit exposed ground and took the fertile topsoil with it." "The weakened rivers were simply not powerful enough to carry all this extra eroded soil and rock out to sea, so they dumped them at their mouths." "For this river, the Cayster, its mouth was exactly where Ephesus was." "As more and more sediment built up, the city was cut off from the sea." "It was a disaster." "The same problem was hitting other parts of the Roman Empire too." "As its arteries became clogged up, the Empire was brought to the brink of a major heart attack." "Marshy sheltered lagoons like this covered large areas of the Mediterranean coastline." "For many ancient cities, these lagoons were their life-blood, teeming with fish, but as the rivers dumped sediment at the coast, the lagoons turned to muddy swamps and the fish disappeared." "Navigating these congested rivers also became a major problem." "Forces of geology were unrelenting." "To give you an idea of how unrelenting," "I climbed to the highest point of the theatre at Ephesus." "The harbour is at the end of that ancient road that we walked down but the harbour itself has been completely filled in by river sediments." "All that's left is a couple of patches of shimmering water." "The sea is 11 kilometres - 8 miles - over there, just visible on the horizon." "This clogging up by river deposits turned what was a port into an inland moth-balled city." "By isolating them from the sea, geology hadn't been very kind to the inhabitants of Ephesus, but unfortunately that was only the half of it." "In ancient times, this was one of the wonders of the world, the Temple of Artemis." "Today it lies ruined, submerged in a water-filled swamp." "These swamps provided the perfect breeding ground for mosquitoes, which brought deadly malaria." "Plagued by disease, the people of Ephesus either died or fled." "And Ephesus wasn't alone." "As other cities suffered the same fate, the very ships that had once ferried goods and ideas around the Mediterranean now began to spread malaria throughout the Roman Empire." "In the end, the Romans could no longer keep hold of the land." "All around the Mediterranean world, their harbours and ports were abandoned behind advancing coasts." "I know the fall of the Roman Empire could be put down to many things, but as a geologist, I reckon rivers causing the silting up of harbours and the resulting deadly malaria must have had a huge impact." "For the Roman Empire, water played a crucial role in both its rise and fall." "Water had brought it prosperity." "It had created fertile river valleys and bustling ports." "But fuelled by the desire to expand, the Romans upset the balance of nature and unwittingly unleashed the destructive power of water." "Today, centuries after the fall of Ephesus, mismanagement is still causing problems on our coastlines." "Just as coastal areas get clogged up by rivers dumping their deposits, so the exact opposite also takes place, which brings us here, to the Costa del Sol." "Millions of tourists flock here every year, but I'm not here for the sun, I'm here for the geology." "The beaches, which are the main attraction, are under threat." "When we come here on holiday, we expect to find acres of this stuff - sand." "But something has happened to the sand all along this coastline." "Things are not as they seem." "This natural beach here completely disappeared, exposing all these rocks." "The sand that we now see was dredged up from way offshore and dumped." "This beach and many others like it along the coast are completely man-made." "The problem is that the demands of the tourist industry are destroying the very coastline people come here to enjoy." "It all starts inland." "Up in the hills, dams have been built, which are great for providing electricity and water, but they also reduce the power of rivers." "Rivers carry eroded rock or sediment from the mountains down to the coast." "When they reach the shore line, they deposit the sediment, creating beautiful natural sandy beaches." "But when dams and reservoirs reduce the flow of these rivers, less sediment is carried downstream." "And when the sediment does eventually reach the coast, there is often another man-made obstacle in its way." "Down here at the coast, promenades like this act as barriers and make it much more difficult for the rivers to deliver the sand to the sea." "What little sand does make it to the beach is then exposed to a natural process called longshore drift." "This is how longshore drift works." "The ocean currents here are moving westwards, that direction." "So what happens is that they bring the waves in at a high angle to the coast, let me show you." "The waves bring the water in at an angle to the beach, say something like that." "As the water goes back out, it goes back down here taking sand grains with it." "The next wave takes the water back in." "Aaah, look what it's done." "The next wave brings it back in, the sand grains trickle back down." "The next one brings it back in and it trickles down." "Back in, trickles down." "Back in, trickles down." "That is how your average sand grain moves along the beach." "Longshore drift takes sand from up there and carries it down here, creating and replenishing beaches, but what happens when humans intervene to upset that process?" "Smart new marinas like this are an essential part of every fashionable resort." "While they may seem like a natural addition to the coastline, they're actually very bad news for beaches." "Marinas act as barriers, disrupting the process of longshore drift." "By stopping sand moving along the shore, beaches further down the Costa del Sol are gradually disappearing." "Coastal environments are very delicately balanced and we meddle with them at our peril." "Water is an immense and unpredictable force." "It can be destructive, but it can also inspire." "All around the Mediterranean, the influence of water has shaped history." "The rising seas around Turkey started one of the first waves of human migration." "Our Stone Age ancestors journeyed far from their home lands." "Their cultural influence has helped shape many of the languages we speak today." "As the water continued to rise, successive civilisations looked for new ways to navigate the high seas." "Geology provided solutions." "The arrival of the compass brought great power and wealth as new trade routes were opened all across the Mediterranean." "On land, geology led the ancient Greeks to a greater understanding of how water could be controlled." "The ingenious Romans developed their own technology to manipulate water, though ultimately it was water itself that helped seal their downfall." "But what of the future?" "Will it be as dramatic as the past?" "Deep down beneath the ocean, even more powerful forces are at work, forces that will eventually destroy the Mediterranean." "Three great plates - Arabia, Africa and Europe - are being pushed together, squashing the land masses of the Med in an enormous vice." "Eventually North Africa will crush into southern Europe." "The Mediterranean will literally squeeze shut." "In 30 million years, the Mediterranean Sea will be pushed up into the Mediterranean mountains." "Some day, people will be skiing here and I don't mean water-skiing!" "Subtitles by BBC Broadcast 2005" "E-mail us at subtitling@bbc.co.uk" "For further information on Open University programmes, please go to open2.net" "There's one rock that can cause catastrophic climate change." "A rock that has helped to shape modern civilisation..." "And is essential to life itself." "What is it?" "It's an edible rock - salt." "To show you why this holds the secret to our survival and success," "I'm going on a journey - a journey through 190 million years of geological change." "I'll see how salt saved the ancient Egyptians from starvation... ..how our Stone Age ancestors managed to find it in an icy Mediterranean wilderness... and I'll tell you a salty story of Venice that you won't hear from the tour guides." "I'll show you how all this... our world, our civilisation, even you and me, might not be here if it wasn't for salt." "The Mediterranean is one of the world's most popular tourist destinations." "But I'm not here for a holiday." "For me, as a geologist, the Med is an ideal place to understand how salt can have such a dramatic effect on our climate, our civilisation and our survival." "Salt is fundamental to life." "Without it our nerves, lungs, muscles and even hearts won't work." "We're constantly losing salt when we sweat." "But our bodies can't make salt, so we have to eat it." "We need salt to survive." "Today it's all too easy to add it to what we eat." "But we don't need to do this." "Our food naturally contains enough salt." "So how does it get into our food in the first place?" "To show you, I'm going to leave the sunshine behind and travel back 20,000 years to a time when ice and snow covered much of Europe." "I've come to Lapland in the far north of Norway." "This is the nearest that I can get to how Europe would have been almost 20,000 years ago when there were woolly mammoths in the South of France and reindeer in Paris." "It gives me the chance to see how our ancestors found the salt they needed to survive in a frozen, inhospitable world." "And to discover how this world would eventually be destroyed by salt." "20,000 years ago our Mediterranean ancestors lived a nomadic life hunting and gathering food." "They thrived in a frozen world with no farming, and hardly any fruit or vegetables, thanks to reindeer." "The original fast food." "The only problem was catching it." "Think I'll leave that to the experts." "It's still possible to sample the hunter-gatherer diet by visiting Lapland's Saami people." "Like the Saami, our Mediterranean Ice Age predecessors ate a diet made up almost entirely of reindeer." "But where did they get their salt from?" "Fortunately for the Saami and our hunter-gatherer ancestors, in a world with few vegetables, reindeer came ready salted." "Hello." "Excuse me, can I come in?" "Are you decent?" "Today, the Saami offer tourists a taste of this ancient way of life." "OK, Scotch broth, super." "I've joined them for a traditional meal." "OK." "Wonderful, thank you." "Thanks." "What is this?" "It's reindeer meat." "Reindeer meat?" "And what?" "And also a reindeer tongue." "This is tongue?" "This is reindeer tongue?" "Ah, OK." "And what do I do?" "Do I eat it?" "What do I do, eat it whole?" "But maybe you must cut it up, with a knife." "This is not a good knife." "Oh, my gosh." "This is better." "I'm going to chop my finger off." "Oh, it's the tastiest bit of the tongue then." "Oh, it's like kidney." "Delicious." "I mean delicious." "Honestly." "And it's actually very good for some of man's most important abilities." "Oh, yeah, what...?" "Tell me more." "Well, it's sort of a Norwegian form for Viagra." "Viagra?" "Yes." "This is Viagra." "Fantastic." "Yeah, be careful." "All right." "Saturday night, out with your friends in Oslo, would this be what you're eating?" "No." "Reindeer kebab, after the pubs have shut." "No?" "But what if there were no vegetables?" "No potatoes, no rice, no carrots?" "It would be too much." "I mean, that's what the hunter gatherers..." "Apart from a few berries and some nuts, this was what they were eating." "In fact, reindeer meat contains plenty of salt." "But where, in an icy wilderness like this, did the reindeer get it from in the first place?" "We all know that salt is soluble." "Much of the Earth's salt is dissolved in oceans." "But there are tiny traces of it in water everywhere - in streams, in rivers and in the ground beneath our feet." "Water in the soil, with its tiny traces of salt, is picked up by plants." "When glaciers covered much of Europe, plants could be pretty thin on the ground." "But the reindeer knew where to look for them." "They dug through deep snow to eat the frozen moss underneath." "The moss contained salt, and by eating it so did the reindeer." "Which meant that reindeer meat provided all the salt and other nutrients the hunter gatherers needed to survive." "Turns out, unless you were a Stone Age vegetarian in search of a salad, the ice age wasn't that bad after all." "The animals that thrived in the cold and icy climate." "provided humans with a perfectly healthy diet." "But then, thanks to salt, all that was set to change." "Salt, the very thing we needed to survive, was about to destroy the diet we'd come to rely on." "Imagine this is the sun... and that snowball is the Earth." "It turns out that the Earth's orbit around the sun isn't the perfect circle that we might imagine." "The Earth's orbit changes from an almost circular, to an oval path, and then back again." "The whole cycle takes about 100,000 years." "Not only that, the angle that the Earth spins on its axis varies as well." "If this is the North Pole, then over thousands of years that angle changes, shifting the Pole from pointing towards the sun when it warms up, to facing away from it when it cools down." "All this tilting poles and changing orbits means that the amount of heat from the sun that the Earth receives varies." "As a result of which, 18,000 years ago, the whole planet got a little bit warmer." "As the Earth's orbit changed, the world warmed up." "But this alone wasn't enough to take the world out of the freezer." "Here in the Arctic, there was something else, something that would help to dramatically change the climate." "And that something was salt." "Salt plays a major part in driving ocean currents." "It helps to move water between the Earth's oceans." "These currents dramatically affect the world's weather." "18,000 years ago, combined with changes in the Earth's orbit, the currents helped to transform the climate, and shape civilisation." "And it all started in the Arctic." "Here, cold, dry air evaporates the sea water." "But salt can't evaporate." "It's left behind." "This makes the remaining water saltier and denser, so it sinks down into the deep ocean." "As the salty water sinks, water from the south has to move northwards to take its place." "And when this water reaches the Arctic the process begins again." "Cold air evaporates the water." "It gets saltier, sinks, and pulls yet more water up from the south." "These currents are like a giant conveyor belt." "But this salt conveyor moves more than water." "It also moves heat." "Imagine that walkway up there is the Atlantic Ocean." "And where I'm standing is the Pacific Ocean." "Warm water from the equator moves south to north, like me, through the Atlantic and eventually into the Arctic." "As this warm water moves north from the equator, it raises the temperature of the sea and the air above it." "It was this conveyor, in combination with a shift in the Earth's orbit, which dramatically changed the climate 18,000 years ago." "As the planet got warmer, thanks to the salt conveyor, the increase in temperature was spread up into the icy Arctic." "The result - a massive meltdown." "The ice that covered much of Europe slowly retreated." "People in the south could only look on as their dinner moved north." "Salt had changed everything." "But it would also hold the key to survival in this warmer world." "Egypt, one of the Mediterranean's most popular tourist destinations... ..with its baking sun and awe-inspiring ancient monuments." "It's also the perfect place to discover how the hunter-gatherers who didn't head north with the reindeer survived when the world warmed up." "For the last few thousand years, Egypt has been an inhospitable desert." "Salt had helped create a warmer world for the ancient Egyptians." "But they did more than just survive in this scorched climate." "They went on to build one of the most successful civilisations in the ancient world." "I'm going to sidestep the tour guides to show you how, although salt caused the problem, it also provided the solution." "As the world had got warmer, the glaciers that covered much of Europe began to melt." "Water was released back into the atmosphere." "It fell as rain and eventually found its way to Egypt." "The Nile river is the lifeblood of Egypt." "This water falls as rain over 3,000 kilometres away in the highlands of East Africa and Ethiopia." "As the water runs off the mountains, it flows to the Mediterranean Sea, going straight through the heart of this vast dry country." "Thanks in part to salt, the world was warmer and wetter." "Egypt was blessed with the world's longest river and on its banks was some of the most fertile land in the Mediterranean." "A whole new way of life was about to emerge." "In the new warm and wet climate, wild wheat and barley began to spring up around the Mediterranean." "Slowly the hunter-gatherers began not just to gather but, through accident, trial and error, to actually grow their own cereals." "It was basically the first GM experiment." "By carefully selecting seeds from the most suitable plants, these early farmers domesticated cereals and developed the wheats that were most suited to making bread." "Bread provided people with a cheap, filling food." "They began to cultivate other wild plants, like vines and olives." "Farming had been born and with it a whole new diet." "With the help of milk and the occasional piece of meat from the animals they domesticated, these farmed foods would become the staples of the Mediterranean diet." "By about 10,000 years ago, the seeds of modern Mediterranean civilisation had been sown." "There was a new diet, a new warmer climate, and a new way of life." "For the ancient Egyptians, life was beginning to look good and it seemed they had everything they needed to thrive." "But this incredibly successful civilisation was also vulnerable." "The warmer world had provided a new diet, but it also created a new danger... one that would kill thousands." "Excuse me." "Can I ask you a question?" "Just one question." "The question is, what do you think is the most dangerous thing in the Mediterranean?" "I think the sharks." "Sharks?" "Yeah." "The sharks in the sea." "I think shark, but also unexpected storms." "Alcohol." "Alcohol?" "What do you think is the most dangerous thing in the Mediterranean." "Tornado." "Tornadoes." "I think it's a shark." "Shark." "Shark!" "I think the heat, the heat and the dryness." "And the fishes are in the sea." "It's the rising of the...the seas." "Earthquake." "Oh, that's a good one." "I think war." "War?" "There's something in the Med that's killed more people than war, disease, alcohol and sharks all put together... and that's water." "Or rather the lack of it!" "When salt helped to melt the ice, the climate that resulted could be perfect for growing crops." "But the new farming civilisations relied heavily on this weather remaining favourable." "And nowhere was it more precarious than in Egypt." "To the ancient Egyptians, the annual flooding of the River Nile was crucial." "But sometimes the rain didn't fall and the Nile didn't flood." "The results were catastrophic." "Crops turned to dust." "Famine followed." "And these droughts could last for years." "Farming, on which the ancient Egyptians relied, lay in ruins." "The people starved." "They prayed to their gods for help." "But prayers weren't what the ancient Egyptians needed." "Their whole way of life relied on an unreliable climate." "They had to find a way to protect themselves." "And salt was about to provide a solution that would help the Egyptians combat famine." "The story of how salt saved the living from starvation started in a most unlikely place..." "..in the tombs of ancient Egypt." "The ancient Egyptians believed that after death a person travelled to a new life, the afterlife." "And to get to there the body had to remain intact." "The only problem is, if you put a body in here, it will decay long before it makes it to the afterlife." "The solution was on their doorstep." "Outside, in the desert." "The ancient Egyptians noticed that bodies that had been buried directly in the sand still had skin, nails, even hair, long after they'd died." "This body, now in the British Museum, was buried in the Egyptian desert over 5,000 years ago." "It's so well preserved even his ginger hair is still visible." "It was a combination of very dry and salty sand that preserved the bodies." "The sand absorbs the moisture and helps to kill the bacteria." "The proteins in the flesh are forced to unwind, similar to the effect of cooking." "This stops the rot that would normally happen after death." "It was salt that held the secret to a successful afterlife." "By burying a body in salty sand, it would remain intact for its new life after death." "Back in the tombs and pyramids, the ancient Egyptians now knew how to preserve their dead." "But they still had to make the process work, not in the dry desert but in the dank, dark tombs and pyramids." "With the lessons learned from those burials in the sand, the answer was simple." "Rather than take the deceased to the desert, the ancient Egyptians found a way of taking the desert to the deceased." "They scraped up salty sand from the desert and packed it around the body." "After 40 days, the body had been mummified." "It was ready for the afterlife." "But more importantly, the Egyptians had unwittingly stumbled across a way to overcome famine." "They were among the first people in history to realise the preservative properties of salt." "And they didn't stop at bodies either." "As well as jewels, gold and even the occasional slave that archaeologists found in Egyptian tombs, there were things like this." "The Egyptians preserved food in the same way as they would a body." "They would pack it in salt to draw out the moisture, wash it and wrap it." "All so that mummy wouldn't go hungry in the afterlife." "This knowledge of salt's properties was the weapon the Egyptians needed." "They realised that if you can preserve food for the dead, you can do it for the living as well." "The ancient Egyptians used salt to preserve fish and meat." "But instead of burying them with the dead, these preserved foods could be stored until they were needed and then eaten by the living." "From now on, if the rains failed the Egyptians wouldn't starve." "So salt, the stuff that had helped create the unreliable and warmer climate, turned out to be the very thing that helped the Egyptians, and others, survive in an unpredictable world." "Salt had helped to change the climate and led to drought and famine." "But by using it to preserve food, the Egyptians found a way to fight famine when the harvests failed." "Food preserved with salt became an essential part of Mediterranean life." "It soon became a rock that everyone wanted." "And this demand made it a valuable commodity." "Now another civilisation would find a way to satisfy this demand... ..and get rich in the process." "To find out why, I'm going to have to go back millions of years, beyond the ice age, to a time when the Mediterranean never existed." "Imagine this the soup is a great ocean called the Tethys." "200 million years ago this stretched from the Straits of Gibraltar, east to the Pacific Ocean, covering the area of the Mediterranean that we now visit." "But all this was about to change." "With some help from this bread, I can show you what happened." "This bread is a vast land mass." "This bit here is Europe and this bit is Africa." "Thanks to processes deep in the Earth, the plates move, roughly at the rate your fingernails grow." "It might not sound fast, but in geological terms" "Africa is in the fast lane speeding towards an unsuspecting Europe." "The two plates collided in a massive rocky pile-up." "Under great pressure, the African plate squeezed against the European plate, with dramatic consequences." "Mountains." "Mountains like these are the beautiful product of that geological pile-up." "Squeezed between the European, African and Arabian plates," "Lebanon is home to some of the highest mountains around the Mediterranean." "But rocky land is difficult to farm." "The Phoenicians, the people who lived in Lebanon 3,000 years ago, couldn't make their fortune as farmers... but they would make it from salt." "And their success story began in the mountains." "Thanks to the higher altitude and rainfall, they had an abundance of trees." "The resourceful Phoenicians put all this wood to good use." "They used it to make boats." "And they soon became master boat builders and sailors." "They were about to embark on a journey that would lead them to great wealth and power." "The Phoenicians would become the first civilisation to make a fortune from salt." "Like all the ancient sailors, the Phoenicians rarely ventured far from home." "They navigated by sailing along the coastline from one familiar landmark to another." "This was a slow process, and limited them to sailing only short distances." "But nearly 3,000 years ago, they realised there might be a way to sail further than ever before." "It was after dark that they saw something really useful." "The Phoenicians were among the first people to use the stars to navigate." "The realised that by measuring the height of the North Star above the horizon, they could calculate their latitude, their position north or south." "But the thing is, it's quite hard to do that when you can't see the horizon and when the boat's all over the place." "But that is about 35 degrees, and that gives us our latitude - the distance from the North Pole." "Thanks to the stars, the Phoenicians could sail across open water, far out of sight of land." "And when they did, they spotted an opportunity." "Trade had been going on between neighbours for millennia." "But the Phoenicians realised that they could expand this trade across the length and breadth of the Mediterranean." "They built a string of ports and trading posts around the region." "Using these, they traded goods from Lebanon in the east to Spain in the west, from the coasts of Africa to Europe." "But for the Phoenicians perhaps the most important place of all was the base they established right in the middle of the Med... on the island of Sicily." "On their long journeys across the Mediterranean, the Phoenicians used Sicily as a stepping stone." "They colonised the island and turned it into a vital link in their Mediterranean trade network." "But they discovered that Sicily had something else to offer." "Tuna." "Lots of tuna." "Every year millions of tuna leave the cold Atlantic Ocean for the warmer waters of the Mediterranean." "They swim straight past Sicily, making it one of the best places to catch them in the Med." "This abundance of tuna presented the Phoenicians with a great business opportunity." "By using salt to preserve the tuna, they could ship their catch across hundreds of miles of sea." "If they could transport the tuna, they could sell it at trading posts from one end of the Mediterranean to the other." "Like the Egyptians before them, if the Phoenicians wanted to preserve their catch they needed to find salt." "But unlike Egypt, there were no dry salty deserts here in Sicily." "If the Phoenicians wanted to preserve their catch they'd have to find another way to get salt." "They didn't have to look far." "They were surrounded by the stuff." "In the sea." "The problem was getting the salt out of the water." "But the Phoenicians found the answer." "They harnessed the natural process of evaporation to extract the salt from the sea water, and began doing this on an industrial scale." "By trapping sea water in marshes near the coast, just like these, and using the heat from the sun, they extracted salt from the sea." "Salt's preservative powers had made it the most important commodity in the Mediterranean, and the Phoenicians now had an unlimited supply." "This was geological alchemy." "The Phoenicians had turned worthless sea water into white gold." "But how did all this salt get into the sea in the first place?" "Why is the sea salty?" "Because, er, the salt is in the sea." "No, no, no." "Because the rain is the same." "The rain is the salt." "Salty rain?" "I need to ask you one ques..." "You don't speak any English?" "No?" "Because...because...because..." "Because the land have a little part of, er... sodium chloride." "Sodium chloride." "Yeah, yeah, yeah." "Yes." "Only this." "Because, er..." "Che...?" "Oh, dear, I don't know." "This is harder than I thought." "The legend of a man with a magic... magic..." "Salt thing." "Salt." "In the sea..." "Ah, right." "So he salted the sea?" "Yes." "Well, that's probably as good as any." "Grazie, thank you." "The real reason is time, and lots of it." "Hundreds of millions of years." "As rain falls onto land, it runs into streams and rivers, or filters down through the earth." "On its journey, the water collects tiny traces of minerals from the rocks and soil." "Including sodium and chloride - the ingredients of salt." "Eventually most of the water finds its way back to the sea." "And that is where time comes in." "With the help of these swimmers and their beach balls, I'll show you what happened." "OK, come on." "I know this is going to be crazy." "Just come in." "Is everyone here?" "You guys are droplets of water..." "agua, OK?" "And you've fallen as rain down onto the mountain here, yeah?" "OK?" "OK?" "All right, so what I want you to do is the water picks up dissolved substances, salts." "OK, so...so this beach ball and this beach ball are salts." "This is sodium, and this is chloride." "So you can be sodium, chloride." "You all need to be salts, so here's another sodium, chloride..." "OK, salt." "Some more sodium." "OK, now we're going to flow down to the ocean as a river." "Let's go." "Let's go, get in the pool." "Dive, dive, dive." "At first there wasn't much salt." "So if you tasted the water billions of years ago it wouldn't have been very salty at all." "But as the sun heated the sea, the water evaporated and rose up into the atmosphere." "But salt can't evaporate." "It got left behind in the sea." "Meanwhile the water in the atmosphere fell again as rain over land, and picked up even more salt and took it back to the sea." "Where the whole process began again and again...and again." "And that is how, over millions and millions of years, the sea becomes salty." "So by the time the Phoenicians set foot on Sicily, the Mediterranean was salty enough to taste." "And this meant they could extract an almost unlimited amount of salt from the sea." "The Phoenicians had harnessed the natural process of evaporation taking place all around them." "With the salt they produced, they made a fortune." "From their mountainous homeland in distant Lebanon... ..they'd come a long way." "They'd built boats... learned to navigate... and created a Mediterranean trade network." "A vital ingredient had been salt." "In this new world of trade, salt would become a valuable currency in its own right, used to buy and sell goods across the Phoenicians' trade network." "For now, by building salt pans around the Mediterranean, the Phoenicians controlled the region's economy." "A tiny nation had become a Mediterranean superpower." "A journey that began out of necessity led the geologically impoverished Phoenicians to become the first truly Mediterranean-wide civilisation." "Unfortunately it wasn't to last, and it was the Phoenicians' very success that led to their downfall." "That's the thing about success, it breeds envy, there's always someone else wanting to get in on the act." "And men being men, that usually means one thing...war." "For the next thousand years, wars raged around the Mediterranean." "The Phoenician empire, which had once seemed so mighty, was soon forgotten." "Waves of Greeks, Romans, barbarians and Arabs fought to control Mediterranean trade... and with it, salt." "Out of this destruction came Venice." "By the Middle Ages, the city had emerged as the greatest Mediterranean trade empire of all." "And it was here that salt, which had dominated Mediterranean trade, would lose its value." "Perched on a series of sandbanks and surrounded by sea, Venice was an ideal place to make salt." "For hundreds of years, Venice's salt pans had made the city rich." "The profits it made from salt are reflected in the city's opulent architecture." "But all this was about to change." "And in a strange irony, it was salt's effect on the climate that would end its role as a currency." "Grazie, Roberto, grazie." "At the start of the 13th century, the Med and northern Europe were ravaged by floods and storms." "The consequences for Venice's coastal salt production were awful, with a third of the pans destroyed." "Something had happened to change the climate once again, and the reason for all this change, we think, was salt." "Remember these?" "They helped us see how salt plays a vital role in controlling the Earth's climate." "Salt in the Earth's oceans helps move around the heat, like a giant conveyor belt." "For thousands of years, salt had driven the system that brought warm water from the Pacific to the cold Atlantic." "This had helped to keep northern Europe warm." "Then 800 years ago, we're not sure why, but the whole system stopped." "Heat was no longer being circulated by the ocean conveyor belt." "The Earth cooled, just a little, but enough to make the climate colder and stormier." "And it was those storms that damaged, among other things, production of Venice's salt." "Storms ravaged the Venetian salt pans." "It became harder and harder to produce salt." "But salt remained a valuable commodity." "The Venetians had to get it from somewhere." "And if they couldn't make it, they'd have to take it from someone else." "The mighty Venetian navy seized control of salt pans around the eastern Mediterranean." "The city's control of this area gave Venetian traders almost exclusive access to the great ports of Constantinople and Alexandria." "Here they bought exotic goods, carried over land and sea from India, China and the Far East." "And by selling these luxuries to the rest of Europe," "Venice became the richest city in the world." "At the height of the Middle Ages, wonderful palaces - like these - were built on the profits that Venice made from trade." "But not only did buildings get more ornate, food got spiced up too." "Spices, above all the luxuries the Venetians bought in the east, captured the imagination and taste buds of the west." "These are all the spices..." "Sarah Cosiggia is an expert on medieval food." "This is what it's all about, you know." "And these were definitely the greatest ingredients you could get in Venice in the old days when Venice was the leader of the spice trade." "There are lots of them, you can see." "Incredible colours as well." "These were among the most common spices in the medieval dishes." "Right." "You see here, for instance, cloves and, er, the nutmegs." "Nutmeg." "There's nutmeg, yeah." "And then even saffron." "Oh, yeah." "This is saffron." "Yeah." "Well, saffron was also used in order to dye actually dishes, in order to get the colour of gold." "Then see the cinnamon." "Cinnamon and ginger." "And ginger also." "So where are these from?" "From India and China, both of them." "Oh, yeah, we got some pepper, which was the most expensive spice." "And one of the very first to be imported to Europe." "So pepper was the most expensive spice?" "Yes, the most expensive one." "Salt had at last found its perfect partner - pepper." "From now on, in kitchens throughout Europe, the two would be inseparable." "But it was spices like pepper that spelt the end for salt as such a valuable commodity." "Oh, here you are." "Hi." "Hello." "Buongiorno." "Ready to...to cook now?" "Yeah." "Oh, I need an apron." "Is this for me?" "Yeah, that's for you." "I'll put it this way." "You can tell I'm a man then." "What is this?" "What is in the sauce?" "'Food was no longer limited to what could be grown around the Mediterranean.'" "I recognise water." "They're stuck together." "Gently, gently, just a little bit." "'Now people enjoy food and exotic goods from across the known world.'" "We're not going to eat all that." "We can try though." "We'll have a good bash." "The saffron is glowing..." "'The taste for spicy food quickly became an insatiable appetite." "'And, by the 15th century, this demand made spices like pepper far more valuable than salt.'" "I didn't want to be rude..." "'But reminders of salt's powerful past were everywhere.'" "I haven't seen any salt." "Where is the salt on the table?" "Well, it's over there, because, er... well, the social rank was gauged by the position of the salt on the table." "Ah, so I'm quite far away from that salt." "Oh, well, in this case, yes, the main chef." "I think that's fine!" "Today, but maybe tomorrow, who knows?" "It could be...just close." "So salt wasn't just a flavouring, it also established your social rank." "No, well, in...in the... here the...the word salary, for instance, comes from salt." "Because that's a way...that the Romans used to pay their slaves for the labour work." "Worth their salt." "With salt, yes." "So 'salario' comes from 'sale', so from salt." "Salt's legacy is everywhere." "In our food, on our tables." "Even in our language." "Salt no longer has the power to build or destroy empires." "But its power to upset the delicate balance of our climate remains as real as ever." "Because the salt conveyor transfers heat, it plays a crucial role in moderating the planet's temperature." "But now we may be disrupting that sensitive system." "We could be on the brink of the next big change." "By burning huge quantities of fossil fuels, we're increasing the amount of carbon dioxide gas in our atmosphere." "Carbon dioxide is a so-called greenhouse gas." "It traps the heat from the sun and creates a greenhouse effect." "This causes the whole planet to warm up." "And that's where things could go wrong again with the salt conveyor." "Such global warming could have a dramatic effect on the Earth's poles." "Because if ice caps melt, this would add a massive volume of fresh water to the oceans." "All this fresh water in the sea would dilute the salt even further and water wouldn't be dense enough to sink." "Just like it did during the time of the Venetian empire, the salt conveyor could slow down again." "Or worse still, it could stop altogether, taking us back to the climate of our ice-bound hunter gatherers." "With no warm currents from the equator, Europe and North America would become frozen wastelands." "This unimaginable winter would last for hundreds, perhaps even thousands of years." "But nearer the equator, with no cool currents from the north, things would get much hotter." "Scary stuff." "To some scientists this is a disaster waiting to happen." "To many it's just a remote possibility." "The truth is, nobody knows for sure if and when the conveyor could stop." "But whatever happens, one thing is guaranteed." "Salt will be crucial to the outcome." "The story of salt's far from over." "It's funny how we take it for granted." "For further information on Open University programmes, go to..." "E-mail us at subtitling@bbc.co.uk"