Let's talk about the theory of continental drift. yeet Why don't we look at a world map? Have you ever seen one of these? Well of course you've seen one of these. Everyone has seen a map of the world in fact you probably first saw a map of the world when you were in kindergarten and what you may have noticed similar to so many people before you is that if you look carefully at the Continents the giant land masses covering about 29 percent of the earth if you look at them carefully they almost look like puzzle pieces like they fit together Especially if you look at certain parts of the world Like the eastern coast of South America and the west coast of Africa for example. They look like they belong together now I hate to break your hearts, but this is not a groundbreaking discovery in fact people have known this for hundreds of years Most people have just taken it for granted that that's just the way the continents look But there have been a few brave scientists throughout history who have thought that it must be something more Let me introduce you to one this is Alfred Wegener Alfred Wegener was a German meteorologist. He studied weather he lived in the late 1800s and early 1900s and as a weather person a scientist of the Atmosphere of course Vagner spent a lot of time looking in maps and so he noticed this strange shape Phenomenon just like you did The problem is he couldn't get past it. He actually devoted his whole life to it He came up with a radical theory that suggested that the continents were actually once connected and then somehow Ripped apart to where they are today He came out and he said I think the continents are moving of Course people thought this was kind of a silly thought to have how could a continent possibly move? But Vagner really thought that this was the case and so he devoted his whole career to studying this and coming up with proof of this radical idea in Fact Vagner didn't just think the continents were moving he actually believed that there was a time when they were all connected and they have Since drifted apart to their current look patience He even came up with a name for that supercontinent that existed in the past he called it Pangaea the supercontinent that he believed existed about 250 million years ago Pangaea or Pangaea is actually an appropriate name It's a greek term that means entire earth or all earth So if you think about it when all the continents were together if vector is correct It would make sense to call that landmass pan, Gaia or Pangaea Here's what he thought it looked like you can see within this diagram the modern-day continents of North America Africa South America Antarctica India etc But they don't look quite the same way. They do today and of course They're in totally different positions all connected into this one supercontinent Now people thought Vagner was a little bit nutty and so he knew that if he was going to make any headway with this idea he had to come up with evidence and So we're gonna take a look at four pieces of evidence that Victor put together To prove to the public that the continents had in fact drifted Let's take a look at his first piece of evidence. We'll go back to this map here now the first piece of evidence We've actually already discussed It's simply the observation that the continents appear to fit together as Simple as that Vegh nur didn't believe that this could be simply a coincidence He feels like there's no possible way the continents would have this appearance Just randomly and so this becomes evidence number one we will call it the Apparent fit of the continents the fact that they look like they fit together and just to expand on that a little bit Essentially the coastlines of the continents appear to fit together kind of like the pieces of a puzzle But that's not enough so vecna went back to the drawing board He dug through piles of books and libraries and became quite interested in fossils and other evidence of prehistoric life in Fact Beckner came particularly interested in that guy who just swam across the screen the Meza soros now Let me tell you about the meso source. This is an ancient reptile that lived only in shallow freshwater What's interesting though is that there's only two places in the world where we find fossils of this freshwater creature? One place is the eastern coast of South America and the other is the western coast of Africa Now there's a couple possible solutions for this now either the Meza source was living on one of these continents and somehow learned how to fly across the Atlantic Ocean to Inhabit the other side of the other continent But that's not likely the Meza source certainly could not fly and we know the Meza source couldn't have swam across the distance is just too great and They can't survive in salt water, so that's out of the question Maybe the water was frozen and he walked across well That's a possibility, but there's really no evidence to support that and so what vector said is that while the Meza source roamed the land? Africa and South America were connected and they were able to freely walk across the land masses and then after going extinct the land masses were torn apart and Separated carrying some of the fossils to what would become South America and some to what would become Africa interestingly Vagner looked into this and found that there were other organisms that lived in the past that had similar fossil distributions Sign onethis life stress or sandglass a terrace being amongst the more Notable ones these fossils all have these very unique distribution patterns that suggest that the continents were once together and In fact if you in reassemble the continents and map out the locations of these fossils, they line up perfectly so That's our evidence number two we call it fossil correlation correlation Simply means matching up so matching up fossils on either side of the ocean to summarize identical fossils have been found in the rocks on either side of the ocean and Therefore the continents were once connected and must have drift drifted apart but Vagner knew he needed a stronger case and so he went back to the library yet again and became fascinated by rocks and Geologic structures like mountain ranges of the past and he found a really interesting pattern not unlike what he found with foul In fact if we go back to our world map here and let's zoom in on the North Atlantic Here if you look at the mountain ranges in the northeastern United States and the mountain ranges in Northern Europe They match up perfectly and what I mean is that they are made of the same type of rock and the same age of rock now of course anything is possible and the same exact rocks could have formed in two different locations at the same time but geologically that's unlikely a better explanation is that these mountains were once connected and as the continents move they tore them into two and That becomes evidence number three We call it rock or mountain correlation and what we see is that? identical rocks and mountain structures have been found on either side of the ocean Suggesting that the continents were once connected But we need one more, and this is probably the most complex of them all Again, Vecna returned to the librarian this time he returned to his roots as a meteorologist And he began to look at past climate data meaning He looked at evidence of cold and warm weather in different parts of the world and he found something fascinated See he first looked into glaciers So glaciers are these giant? Rivers of ice that move slowly across the Earth's surface and of course glaciers have to be found in cold parts of the earth Today they're restricted to only the highest mountaintops and of course the North and South Poles of the earth Something interesting about glaciers is that they move and when they move over the rock beneath? They leave evidence in the form of scratches that we call glacial striations, which you see here Now how does this relate to climate to a continental drift? Well if we look at our map if you look in the present day tropical rainforests of South America and Africa you will find glacial striations here in These two regions you find these scratches in the bedrock now if you think about that how could there be glaciers in a tropical rainforest? Unless it wasn't always a tropical rainforest This suggests that these continents were not always in there war Equatorial regions like they are now They were once down near the South Pole. Where could have been cold enough to have glaciers, and they have since drifted apart But Vagner wanted more from this climate data, and so he began to explore a little deeper, and that's when he came across this rock This is a sedimentary rock called bituminous coal we know it because we burn it for energy. It's a fossil fuel What we know about bituminous coal if you were to look in in earth science reference? Tables you would see that bituminous coal is made from compacted plant remains So picture tropical plants like this dying on this forest floor and getting compressed over millions of years to form coal Now let's look at where coal is found on earth Anywhere you see this little icon. We have found coal deposits now. Let's think about this coal forms from tropical plants yet It's found in Antarctica in northern Europe in northern Asia And the southern tip of Africa and Australia and in the northern United States These are not tropical climates yet They have coal Which is evidence of a past tropical climate and so this just like the glaciers? Suggest that the continents have moved over time and that becomes evidence number four Paleo climate data or past climate data the observation that coal has been found in cold areas and that glacial evidence has been found in warm areas and with these four pieces of evidence vague nner Published his book the origin of continents and oceans in which he laid out his case for continental drift suggesting that all the continents were once connected in a supercontinent called Pangea, which existed about 250 million years ago and since the continent has ripped apart into the present-day land masses that we know so well Later in his life Vagner took an expedition to the North Pole and in this expedition He want to gather more evidence to support his theory of continental drift Unfortunately on a very cold dark stormy day feckner set out on an expedition to gather food for his colleagues and He never was heard from again Feckner died of exposure and was frozen in the ice and his body is actually still there today frozen forever The sad thing about that is that vague nerve was never able to explain. What made the continents drive? What made them move? What made the supercontinent rip apart and so he died before his theory would become accepted by the scientific community? He never got to see his life's work come to fruition That's the story of continental drift, thanks for listening