Chasseurs d'épaves : Les trésors disparus ! - C'est pas sorcier [Intégrale]

It's here! The treasure of my ancestor! And what's in the treasure of your ancestor? Lingons! Plenty of lingons! Hundreds of lingons! Don't panic, it's off the coast of Marseille, we're going to get it! Come on Marcel! To Marseille! Lingons! Marseille! To Marseille! The Mediterranean, you'll see, is a real gold mine for the underwater archaeologists. With all the ships that have sunk here, some even say that it's the largest museum in the world. To give you an idea, we have already listed on the French coasts of the Mediterranean 650 ancient wrecks, that is, wrecks that have flowed here between the 6th century BC and the 7th century AD. And of course, we also find plenty of much more recent wrecks. Let's go! Hi Jean-Pierre! Hello Jean-Pierre! So, which wreck do we start with? If you want, we go on the cargo, the Chahouene. No problem! Let's go for the adventure! And we start with a cargo. You see Fred, you have the choice, because in the Mediterranean, we find all the models for the great pleasure of divers. We can explore, look, but be careful, no question of using it! Here, this is a plane. Well, this one is the same. Everything has to stay at the bottom, because in French territorial waters, when we find a wreck, we must first declare it and we cannot go back without authorization. And what does he do? But no, he doesn't have the right, the law is formal! Well, whatever the regulation, fortunately, it is not yet forbidden to go for a walk on the wrecks to visit them. So Jean-Pierre, it seems that you are one of those who discovered the most ancient wrecks in the Mediterranean. Is that true? To give you a figure, 22. The oldest is from the 6th century BC, the most recent is from the 19th-20th century. How do you find a wreck? Is there a recipe? About 15 years ago, we were looking around for shacks, because who says shacks, says shipwreck, says wreck. But everyone has done it before us. So now, the problem is to dive where no one has dived before. Planier, is it there? Yes. Come on! This is the island of Planier, the wreck is below. It seems that it is not the only one, by the way. Come on, let's dive! Great, he may find my lingots! So, the island of Planier is about 15 km offshore of Marseille. The wreck of the Chahouen, a Moroccan cargo ship, is located south of the island, here. So normally, Fred and Jean-Pierre should not take long to reach it, because it is literally lying on the flanks of the island, and it rests between 4 and 30 m deep. Only, I hope they will land on the Chahouen, because the island of Planier has trapped many other ships. Here, there is the Dalton, another cargo ship. Next to the Chahouen, there are even the remains of an ancient wreck. And there are not only boats, there are also planes around the island. Here, it is a Messerschmitt, a German plane that was shot down during the war. And there, it is a French plane, also shot down during the war. But tell me, Fred, how did your boat sink? Without a doubt, Jamy, after that, a big navigation error, because apparently, when the Chahouen crashed on the island, it was under automatic pilot. That happened in 1970, I reassure you right away, there were no victims. We are going to take a little tour inside. We enter through the big door, we can say that there is still a little open space. This boat, it seems that it slides very slowly towards the bottom. Well, take a good walk, Fred. I'm going to take a little tour on the Calypso with Commander Cousteau. And yes, it is thanks to the invention of the autonomous spacesuit that underwater archaeology was able to develop. And this is not very old. In 1952, the divers of the Calypso explore the wreck of the Grand Anglouet. It is the first major French excavation. For the first time, a methodical work of underwater archaeology allowed to bring back in 1250 dives, 7,000 amphorae, innumerable pottery, the anchors and the on-board equipment that will enrich the museums of Europe. Oh, but Vaster, we are no longer in 1952, and I am the one who tells. And I will tell you that there were so many amphorae that we kept thousands of them there, in this archaeological depot, where they are sheltered from pirates. Well yes, today an amphora is sold for more than 1,500 euros at the black market. And future archaeologists will still have a lot of work because every year in the world there are still 300 or 400 large ships that disappear into the sea. Although all these modern wrecks will also end up disappearing. Isn't that right, Jean-Pierre? It is high. The chawan, which is a kind of steel block, is being destroyed because iron, like most metals, is under the sea water and there will only be a compression barely visible. What happens when a steel object stays underwater for a long time? Well, it is attacked by corrosion. And this can be seen particularly well on cannonballs that have remained several centuries underwater. There is a concretion around the object. This is called a gangue. So what exactly is going on? Well, I don't know if you've ever felt a piece of steel, but try it. There is always a little smell. Well, this smell, these are tiny little pieces of iron that escape from the object to combine with other tiny elements that surround us. Well, in the water, exactly the same thing happens. There is a whole bunch of little pieces of iron that escape from the cannonball to combine with elements contained in the water. Chlorine, for example, which comes from sea salt. It makes iron chloride. Sodium, also, which comes from sea salt. So all these elements regroup around the object. They form a concretion, a gangue, and this phenomenon also weakens steel. Tell me, Jamy, you know I'd like to go for a little tour of the Titanic wreck. Is it far from here? Well, there is a point in gaining strength, and above all, a place to hide, because the wreck of the Titanic is located in the North Atlantic, somewhere off the coast of Newfoundland. Well, here it is, the Titanic. It rests at 3,800 metres below sea level. And yet, when it was launched in 1912, everyone said it was insubmersible. Unfortunately, on its first voyage, it hit an iceberg and disappeared in a few hours. There were 1,500 victims and only 700 survivors. Since 1985, several exploration missions have brought back objects from the Titanic. We managed to preserve them, even if some were really in a strange state. To save an object that has been underwater for a long time, we start by removing the concretion, the gangue. And then, to our surprise, sometimes we discover an object in perfect condition. Well, only in appearance. Because if we don't do anything, this is what happens after a few days, the object completely crumbles, it unravels. So what exactly happens? Well, on the surface of the object, and inside as well, because of micro-cracks, there are still iron chlorides, i.e. iron combined with chloride. The danger is that in the open air, these iron chlorides love oxygen and hydrogen from the air. They combine all these elements and form hydrochloric acid. But hydrochloric acid destroys the iron. Well, to avoid the formation of hydrochloric acid, we will remove an element, we will trap the chlorides by doing an electrolysis. To do this, as soon as we have removed the gangue, we immerse the ball in a bath. Opposite, we have a pot, a new steel plate. Then, we circulate electricity. And there, the chlorides throw themselves on their new prey, the steel plate. The ball is rid of its chlorides, it is saved. And it works really well. Look at this angel of the Titanic in his electrolysis bath. Thanks to this technique, he made totally new skin. It's cute, isn't it? Thanks to another electrical treatment, electrophoresis, we can even save leather or paper. Hey, Jamy, do you know the Christian M wreck? Do you have this in your books? Don't move! This is an ancient wreck from the 1st century B.C., but I don't think there is much left. Well, listen, we'll see. All we can say is that this boat sank about 20 centuries ago. At the time, there were no signs to report this wreck, and it's not the only wreck in the region. How many are there around this wreck? There are many Christian wrecks. There is the Christian A, B, C, D, E wreck, up to the Christian M wreck. The most recent is from the 15th century and we found a treasure of coins on it. Did you visit them all? Almost all of them. Can we still find a small treasure of coins? If we were sure not to find any, I wouldn't be here, going back to the Christian M wreck. Let's go! So, especially when I'm on an ancient wreck, you shouldn't expect to discover a boat with its hull and its masts. For a very simple reason, it's that the wood has been totally devoured by small worms called tares. All we have left to reconstruct the history of the ship is the cargo, in this case, of pottery and some amphorae. Yes, you may not believe us, but it's from this pile of debris that we managed to find out everything. Well, it was a Greek boat about 15 metres long. They found something! What's that? It's a small herd of sheep because this ship had to carry food. Before going back up, archaeologists take a look at the exact position of each piece on a carriage. You see, it's this kind of chessboard placed on the deck. Once everything is noted, we remove the pieces and move on to the next layer. We do all this deburring with this sucker. It's a huge vacuum cleaner that allows us to clear the sediments around the objects. I can guarantee you that it vacuums very well. Thanks to this technique, we review all the layers of the load. This is how we realised that there were two ancient spades on top of each other. Here is another tool used by archaeologists. It's a metal detector that allows us to locate metal objects. I have the impression that the device has detected something because the needle of the detector is a bit excited as you can see. I don't know exactly what it is. This piece is a new clue to date the spades more precisely. The ideal for them would be to find a beam that wasn't attacked by madmen. We often find this buried in the ground. Thanks to the wood, we can determine the age of the tree with which the boat was built. Let's take an example. This beam was found off the coast of Marseille. When we cut it, we can clearly see the grooves. Each groove corresponds to the growth of a year. If we get closer, we can see that each groove is different, because of the climate. From this point on, specialists created catalogs in which we find, year after year, the width of each groove. They did this for several species and several regions. To know the age of this beam, we measure the width of the grooves, and compare it with the grooves of the catalog that correspond to the species, i.e. chain and region of Marseille. We slide it, and as soon as it matches, we have the year, 25 A.D. Tell me, Jamy, can you explain how you made your catalog? Do you have chains that are 2,000 years old in your garden? Unfortunately, no. To make this catalog, we had to work from archives, old beams, old doors, and pieces of wood with dates on them. With this technique, there are catalogs with holes. Understood, Jamy? Now, look carefully. Once we have located all the objects on the beam, we can start going up to the surface. To do this, we deploy a parachute. The principle is very simple. You will see that we use the air that we have in our bottles to inflate the parachute, and slowly it will drag this amphora to the surface. Come on, let's go! With air, we can even inflate entire splinters. So what happens exactly? Two things. This splinter in the open air weighs 800 grams. In the water now, it only weighs 650 grams. It has lost weight because of the Archimedean thrust from the bottom to the top. Thanks to this Archimedean thrust, we only need a force of 650 grams to inflate this splinter. Now, to inflate it, we will use a reservoir that we have immersed. We attach the reservoir to the splinter. For the moment, the reservoir is full of water. We will chase the water with air. The air being lighter than the water, the reservoir, which has turned into mud, goes up and up the splinter. This boat, Jamy, will not fit in your aquarium. It is the Vasa, a Swedish warship that sank in 1628 In 1961, large means were used. Scaffolders passed cables under the hull, air was sent into the floaters, and the 150 tons of Vasa resurfaced. Do you know why it was not destroyed by the crazy people, the little worms who devoured the wood? Because in the cold seas, there is none. The work is not finished. The wood is full of water. It may disintegrate, so it is gradually dried by spraying a kind of glue to consolidate it. It took 20 years of treatment and today we can visit the Vasa more than 3 centuries after its shipwreck. Hey, Jamy, what about the wreck South Cape 1 that we found in the Marseilles? Does it ring a bell? Yes, it is also a wreck from the 1st century BC. You can't go there, it is 70 meters deep. Why? Because you need a submarine. I have one, and the wreck is just below. This time, we enter the field of archaeology of great depths. It becomes a professional story because you need big means. On this boat, for example, we already have a submarine, the Remora 2000. It can dive to 600 meters deep. And that's not all. There is also a robot called Super Achille, and it can work alone at the bottom of the sea up to 750 meters deep. Here, on the bridge, there is a laboratory full of electronics. Here, the research on the wreck is carried out by a robot. This technique was developed by COMEX for the industry and today it is used in submarine archaeology. We have invested a lot of money in oil and geology. Why can't we apply it to archaeology in a decent way, in a perfect ethic? After all, we have money, means, competent people, technicians. We can very well associate with science. With these new means, scientists intend to tackle very deep wrecks, where spongers sometimes have a hard time working. Maybe we could replace them with machines. Can we replace a man completely underwater for this very precise work? I don't think so, but we have to learn how to work without him. And that was the goal of this operation. And with this ship, we can also locate wrecks from the surface, even the best hidden ones. How to locate a wreck hidden in the sand? Well, thanks to metal objects on board, like cannons or cannonballs, and thanks to a magnetometer, a device that measures the variations of magnetic fields. Why are we interested in magnetic fields? Well, the Earth behaves like a big magnet. Its magnetic field moves the compass needle. That's why the needle points to the North. If we now move a metal object between the compass and the Earth, the magnetic field changes and the needle moves. Well, on board Fred's ship, or more precisely, dragged by Fred's ship, a magnetometer records these variations of magnetic fields. And when the ship passes above a wreck containing metal objects, well, we can see it right away. Well, here we go for a little dive in antiquity, let's say, with Henry Deleuze in command of the Raymora 2000. So, to follow us, it's extremely simple. There are, of course, the cameras of this submarine, and then there is also the sonar. The sonar, the little beep, beep, beep that allows to permanently locate the submarine compared to the ship. So, let's go for a dive at 63 meters deep and a descent that will only last 3-4 minutes. With a sonar, we can also spot a wreck. So, how does it work? Well, it's a device that emits sound waves towards the bottom and captures them after they bounce on the ground. Depending on the time it takes to go and come back, we know how far the bottom is. Now imagine, the ship sails on flat bottoms. The wave takes a second to go and come back. If all of a sudden, the wave comes back earlier, well, it's because it has encountered a relief, so it has traveled less distance. Either it is a wreck, or it is a rock in any case. The boat stops and we dive to check. So, right now, we are precisely at 42 meters deep. The originality, the particularity of the Raymora is that it is a huge hub. We have a magnificent view. A glass bubble that is very resistant, of course, because with the Raymora, we can go down to 600 meters deep, but I think it is calculated to go deeper. Yes, the Raymora is calculated at 2400 meters. At 2400 meters, it must implode. So, we take 4, which allows us to work at 600 meters. So, the autonomy of the Raymora? The autonomy is 8-10 hours. On the other hand, in terms of survival, the classification agencies ask us for 3 days of survival, in terms of oxygen, in terms of carbon dioxide absorption, in terms of communication, and we have 4 days, because when you ask for 3 days, you always have to put a little more. And then, it must also be specified that in this submarine, we breathe exactly like on the surface, we are at atmospheric pressure, so we absolutely do not know the constraints that divers and divers face. Absolutely not. When we go out, we open the door, we leave, we are in the same conditions as if we were in a car. Well, in any case, we will continue our descent towards the first century BC. The problem when we dive, it is the pressure. It increases with depth. Only, here, the air pressure that we breathe also increases. Suddenly, small nitrogen bubbles penetrate our body. And if we go up too fast, well, the small bubbles that take volume can become very dangerous. Therefore, we must go up slowly so that the small nitrogen bubbles eliminate themselves. Obviously, everything depends on the depth at which we dive and the time we stay there. Imagine that we do a dive of a quarter of an hour. If we dive at 10 meters deep, well, no problem, we can go up in one go. If now we dive at 40 meters deep, well, we have to start being careful and mark a level of 4 minutes at 3 meters from the surface. If we dive at 60 meters deep, well, the climb will be even longer since we will have to plan 25 minutes of level at 9, 6 and 3 meters from the surface. And then, if we dive at 700 meters deep, well, it would take a month to go up again. So you think that in these conditions, archaeologists prefer to use submarines. So, to illustrate what you just explained to us, it's very simple, since we can go up in one go, without making levels. On the other hand, the cameraman who is with us and who is called René Osé, and who films us, he can stay 15 minutes with us and he will make levels of how long? 45 minutes. Which shows, indeed, all the interest of a submarine to come and work like this, on levels. Hi René! We're going to do a little walk above this level. Ah, well, that's the level of the hundreds of Greek and Spanish children that the COMEX spotted in 1977. This boat probably left the Adriatic, went to the south of Sicily, went to Spain, where there was a load of Spanish children. In other words, we think that the Greek and Adriatic children are children of reuse. Normally they are full of wine, and here they are full of fish, which is already a product. The fish is a resin used to seal the boats. Before knowing all this, we started by putting in water a kind of big underwater hair dryer to remove the first layer of sand. Then the remora slowly flew over the ship's remains, taking pictures regularly. Hi octopus! It's called photogrammetry, and it's the best way to study a deep wreck. By using this technique at a depth of 660 m, this is what we got. A 3D image, a kind of virtual wreck. Archaeologists can study it dry in front of their computers. And now we're going to introduce our friend Super Achilles, who is with us on this wreck. Super Achilles is a robot that can go down to 750 m deep. He has no breathing problems and can do a lot of things. This robot is equipped with a blaster. It's a vertical fan, a small electric motor with a propeller that allows to very delicately clear a pelvis, a dish, a porcelain. And it's also Super Achilles who marked each object with a small buoy to locate it precisely on the wreck's map. He would even be able to go up all the amphorae at the end of the dig. But to go faster, archaeologists and the Comex preferred to use divers who used parachutes like Fred earlier. After a month of work, it's crazy what we learned. We even know the name of the manufacturer of the Spanish amphorae. He's a potter from the region of Matarro, a certain Lucius Volteus. Of course, we don't know everything about these ships yet. There are still little things to learn. And what would really interest me is to know how the captain was, his age, the color of his eyes, well, all that. I think that in a future campaign we will be able to make a perfect photogrammetry of the remains of wood once cleared and have a much better idea of its type of construction and its general shape. What about the captain? The age of the captain, I hope, too. Go on, Fred, dive. I think you're very close to the treasure. Tell me, Jamy, wouldn't the treasure of your ancestor be in a barrel by any chance? Yes, surely, my grandfather loved barrels. Well, look, it's him. I've got your treasure. I've got it, and I'm coming. He found my treasure! We found my treasure! The treasure of my ancestors! I hope it's your ancestor's, because we're not allowed to meet him. Run! Run! What's that? It's not that, it's white beans. Yes, but we also call it lingonberries. Is that why you made me dive? You're going to eat them. Go on, Marcel!