The Cambrian In this class we will talk about petanca (French bowling game), billiards, puzzles, of the flying carpet game. But, although it does not seem so, we will not comment on sports. Or even talk about games. We're going to talk about the formation of our planet. In the previous class we had seen how our world was generated. Let us remember how, according to some, it was formed from a nebula; according to others, from the famous Big Bang or a large meteorite clash. Afterwards we saw our planet turn into a ball of fire. When it was starting to calm down, the game advanced. And now the most important movements were to come. An excellent carom, as in the jargon used in pool/billiards, hit the target in full. The large meteorite, CEA, hit right on us and took us out of our first orbit, to situate us in the present one. It seems to be correcting an initial error of calculation. It was this clash and this game that allowed for the existence of life. It placed us at the right distance from the sun. Before the impact life on Earth was not viable. Furthermore, as a result of the bang, the Moon, our satellite, was formed, with fragments of CEA and the Earth. Our planet won both in spatial position and in volume because CEA increased it in 20% so it is now under our feet. After the tremendous bang, came the unrest and more fire. The Earth roared. To calm the fire down, the water arrived. It was the most intense flood ever. 500 million years of rain. Some scientists set out that it could not be only land water. That it also had to be Extraterrestrial that created our oceans and seas. The zircon suggests an answer as we saw. The result was that the planet became a ball of green water, color that was obtained by the residues of iron that are visible on rocks dating from that era. However, large and thick clouds prevented any non infra- red color from passing through. If we would had had the opportunity to witness the Pre-Cambrian landscape, we would have had the vision of this red colored landscape. But, despite the water contribution, the atmospheric toxic gases, produced by the intense volcanic activity, prevented any type of life. Until the Stromatolite arrived. THE STROMATOLITE Thanks to this single-celled organism the Earth was filled with life. Stromatolite fossils It is the first inhabitant of our planet. A species of alga that adheres to rocks and it would be like our great-great-great- great-grandfather. In the West Australian coast, particularly on the shores of Shark Bay, this organism can be seen, even today. They are thin layers of micro-organisms that capture energy from sunlight and with the remains form this rocky appearance. The discovery of these organisms was a revolution in the research of fossils and the dating of the Earth. While some proposed that the Earth had, at most, 6000 years of age, the dating of some Stromatolite fossils indicated an antiquity of 3500 million years. So the Earth had at least 3,500 million years. Millions of years ago the entire planet was full of these rocky weeds. It therefore had the same appearance as Shark Bay has today. But in order to have life there has to be oxygen and that atmosphere full of toxic gases was impossible and impractical for any organism. Where did the oxygen come from? From this simple kind of alga, the Stromatolite, which, through photosynthesis, is able to breathe these toxic fumes of carbon dioxide and change it to expel oxygen. It’s what our plants do and it is called photosynthesis. This small being changed the color of our house, from green it became the blue planet we know today and made it livable, breathable. Possible. However, once the planet was blue, full of clean air and generating life, new disasters would destroy all this. The Earth was once again going to fall into confusion. Destruction will be created. What happened next is the description of the period known as the 1st worldwide Great Extinction. The nearly massive disappearance of a life occurred for the first time in the history of our planet. What nearly ended with the Stromatolite? The convulsion came from the depths of the oceans. THE THEORY OF THE CONTINENTAL DRIFT At school, the children, experts in solving the great puzzles, when they saw the map of the world, said that the continents fitted together. The same was observed in 1620 by Francis Bacon and after by Benjamin Franklin. But this would mean that the continents moved, and were still moving. Without specific and proven evidence, which could be assured by the academic dogma, teachers could not accept it. They looked at this child intuition with tenderness, indulgence and certain superiority. For them it did not have much logical sense. Moreover, it seemed impossible to prove. The forms were a mere coincidence. Science replied: "What atrocity! How are the continents going to move? The reply came from Germany. The theory of the continental drift was originally proposed by Alfred Lothar Wegener in 1912. The same year that the Titanic sank. Wegener was a German meteorologist, geologist and scientist who developed his theory by observing the map of the Earth as did the children. He realized how the continents seemed to fit on each side of the Atlantic Ocean. In particular Africa and South America. He also based his opinion on the likeness of the fossils from different continents far away from each other, for example, from fresh water only species and also from certain geological formations typical of a certain place. Wegener said that all the present continents must have been united in the past forming a proto continent to later split, slide and end up separating as it is now. In his original thesis, he proposed that the continents were moving on the mantle of the Earth in the same way that a carpet moved on the floor of a room. However, this audacity led to the rejection of the scientific community. His theory was considered as a hypotheses, curious, clever and even funny, but impossible. Saint-Exupery, the pilot as he liked to be called, wrote with great clarity one of the most interesting stories in history: "The Little Prince". The story of the little boy that looked for friends became an anti-Nazi symbol. One of the most famous phrases is: "The essential is invisible to the eye." Well then, when the Little Prince draws a picture and shows it to the adults, they say it is a hat. Disappointed, he completes the picture and says: My drawing is not a hat, but a boa snake, being eaten by an elephant. Then he drew the inside of the snake, so that adults could understand, because adults always need explanations. Indeed, the little prince was right. Hats do not have eyes. If we would have looked better, we would have realized that it was a boa. In the same way, if they had looked better, they would have realized that this curious coincidence of forms between continents seemed to show they had been united further back. The answer and knowing who was right came, as it usually occurs, due to a coincidence. During World War II the Americans allies needed a map of the oceanic crust to observe, without being discovered, the Japanese submarines. They observed some deep cracks from where magma flowed. It had a curious shape. The map appeared to be pieces of a puzzle. When expelling lava and cooling, they moved moving the masses. Wegener and the children were right. There was a time when the continents were united. The pieces fit. Continental crust moved and moves over the oceanic mantle separating an average of 2.5 cm per year. As a carpet on the floor. Similar to the game of the Magic Carpet. This means that Europe and America each year are a little further. The discovery gave the reason to the children and Wegener and opened a new science: the Tectonics of Plates. According to the Tectonics, the oceanic layer is formed by 12 major marine plates and a few smaller ones. Fissure eruptions are generated and where the plates come together it is where there is seismic activity. The reason is very simple: the underwater volcanic activity cracks the oceanic mantle. The magma escapes from the cracks. Then there are fissure eruptions, vapors, and the liquid fire opens its way through where it can and as it pleases. It mainly affects the basaltic stone lid that is the oceanic crust. Just like when we cook with steam and we see that the heat comes out from where it can. Each new gap allows for the lava coming out to cool down, forming a new space. This lava solidifies and creates a new piece of crust. If that space is occupied by a new space, where does the old one go? Well, inside. It is recycled. It is introduced in the mantle where it is mixed with the magma. The movement is like that of the conveyor belts or mechanical escalators. Osaka Umeda Building. Japan. Architect Horishi Hara. Suspended 167 meters. But this activity is not very beneficial. When the continental crust cracks, it produces tremendous damage. The extent of damage depends on where it happens. Depending if it is farther or closer to inhabited areas. If it happens near the earth, earthquakes arise. One of the countries that most suffers from earthquakes is Japan. There everything that is built is anti-earthquake. As these escalators in the Osaka Umeda Building of the architect Horishi Hara, who, with his 167 meters in suspension, and that make them unique in the world. Not suitable for those who suffer from vertigo. But if it happens at or near sea areas, geysers, fumaroles, tidal waves and tsunamis occurr. In this image of Hokusai called "The Great Wave" it shows us his interpretation of the Tsunami. We can see the poor sailors with their faces in fear. This artist and this work in particular will be very important for the Impressionists. He made a series on Mount Fuji during the day, the evening, in winter, in summer. As will later do Cezanne with the Saint- Victoire mountain and Monet with the Rouen cathedral. But it is also very important because Hokusai introduced a new genre: Manga as the precedent of a drawing that contains a story, a narrative intent. In recent times, he has also inspired other artists like the photographer Jeff Wall. Iceland is one of the countries where this activity of the movement of plates is better appreciated. Thingvellir National Park, a place of great historical importance because it was the place where the Icelandic parliament first gathered in the year 930, is also of a geological and unsurpassable significance. There one can see the fault system that separates the American and European tectonic plate. Therefore, it is evident that if compact masses move there comes a time when they will eventually unite at some end. Whilst developing this theory we come up with the super continental cycle or Wilson cycle, proposed by John Tuzo Wilson, who said that every 400-500 million years all the emerged land masses unite, forming a super continent. The next one would be the 4th. The first was called proto-continent Columbia and is believed to have been formed between 2,000 and 1,800 million years ago. Then Rodini was formed which began to slowly come together about 1300 million years ago and from the three or four existing continents. It was a continent that gathered much of the land emerged from the planet. It remained united about 200 million years. It began to break 800 million years ago due to the earthquakes caused by intense volcanic activity. It is believed to have been largely responsible for the Neoproterozoic Glaciations, which ended up with most of the living organisms. And it is believed that it occurred because when splitting and moving, it blocked the warm currents, and the planet froze. The eight continents that were part of Rodini later united again in the global super continent called PANGEA formed around the Permian period 280-240 M. years ago But what was happening with existence in the meantime? With life? The Primary era began 542 M. years ago. The Cambrian period is the first of the six stages of the Paleozoic Era, also known as the Primary Era. At this time there is an outbreak of life because, as we have seen, of the Stromatolites. "Cambrian Explosion". This name refers to the sudden appearance of complex multi cellular macroscopic organisms. Animal life thrives in the seas. The first fish appear. THE CAUSES OF THE CAMBRIAN EXPLOSION The Causes of the Cambrian explosion are unknown. There is no one single accepted reason by the entire scientific community to explain the Cambrian explosion. It is a phenomenon constantly under discussion. It can be the result of several factors, both biological and geological. But with this explosion of life, it seems that the Earth has been subjected to a test of trial and error. Create, develop and destroy. It seems a waste of time, talent, work and effort. So long to create life. So much suffering, for then to have everything covered with the white mantle of the Glaciations. It is curious that when we are preparing a project we quickly proceed to write it on paper. If we are not satisfied, what do we do? We crumple the white paper into a ball and throw it away. We start again with a new sheet white as snow. Just as the Earth has done 15 times. Sometimes you reject most of the project, but part of what is done is of value and is passed on to the new sheet. But at other times, hardly anything is useful, we consider it useless and we don’t consider it. We start virtually from scratch. This has happened 7 times because it has suffered 7 mass extinctions. Is it that Nature makes mistakes? Nowadays the life of some species can survive because as the water slowly freezes it turns into very transparent ice, and the little light that can pass through the huge layer of ice on the sea is enough to maintain the first link in the food chain. THE CAUSES OF MASS EXTINCTIONS How is this new white paper produced? With every ice age? The immediate causes of the mass extinctions are unknown. Although we know the damage caused by volcanic activity. But it does not seem enough, say the scientists, to produce such devastating effects. There is a theory that attributed all or nearly all major extinctions to the meteorite impacts. It has been statistically established that, approximately, each 100 million years on average a kilometric asteroid hits the Earth. If one takes into account that the multi cellular life is present some 600 million years, there has been between 5 and 6 great extinctions since then. The same volcanoes that in many moments created the disaster, also solved the Glaciations. When it was covered with snow, like a blanket, the gases produced the greenhouse effect making the temperature rise until, at least, part of the sea melted. Geologists are beginning to accept the mass extinctions of species of organisms as normal events in the geological history of Earth. FOSSILS When reading "The Wonderful Life” of Stephen Jay Gould, there is a fascination with the beings that are described. Such a technical and academic theme as the Cambrian explosion is narrated with such passion that it makes anyone, even if not knowledgeable in the matter, to want to go to Canada and hit with a geologist’s hammer on the Rocky Mountains chalk of the famous Burgess Shale site. "Burgess Shale" is the name of a town and a famous fossil site in Yoho National Park in Canada, known for its rich remains of invertebrate animals of the Cambrian period about 540 million years old discovered in 1909 by Charles Walcott. What was found there? A burst of life and imagination that had surged millions of years ago. Anything that we could imagine with the maximum of strangeness and creativity occurred in those moments. There were more different species in the primary age that there has been since then. The superb preservation of fossils is of such quality that they exist also in 3 dimensions. Even the digestive system can be appreciated. This is why we have been able to reproduce them with reliability. The drawings of the scenes from the Primary era are a wonder that show the imagination of Nature. The strangest beings met under the water. Let us imagine beings with 5 eyes? Yes, they existed. And who also had a trunk? Yes, as well. And at the end of the trunk a pincer? Why not? Well, this also. So much imagination and creativity has not been in vain. At least in what pertains to the future. It has awaken the creativity of many filmmakers with regard to their characters in science fiction films like BLADE RUNNER and ALIEN by Ridley Scott, DUNE by David Lynch, STAR WARS by George Lucas or the latest of THE HOST Bong Joon-ho. After the burst of life came annihilation. Only the marine sponges and a few simple organisms that could stand up to the glacial cold remained. It seems incredible, right? So much life wasted. Well that's not all. In the Jurassic nearly all animal life was lost. We have existed 800,000 years since our first ancestor. We believe that after all this time we will not disappear as easily as that. The dinosaurs were 160 M. years on Earth and there is no trace of them. We may need to be more humble and should not think we are so important, nor so essential to this planet. In the next class will end with the Flintstones. Funny drawings. We will advance until we meet with Lucy, our first Eva. Thank you very much and until the next day.