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Planet Earth, home to over 6.5 billion human beings! Over the last 100 years, our species's appetite for energy has increased staggeringly. Exciting new technologies, funky gadgets and amazing machines are just some of the things which adds to the energy we demand everyday. But where do we get this energy? Most of the energy found in our planet begins its journey at the sun. As the sun shines down on the earth, some of this energy is captured by the green plants, and stored. When these plants are eaten, some of this energy is passed on. And, if that animals are eaten, it's passed on again. This is a simple food chain providing the energy our bodies need. However, getting hold of this energy, so we can use it to power technology and machines, can be tricky. We don't usually use the energy stored inside plants and animals alive today. But, we do use the energy stored in ancient animals and plants from the past. To find this energy, we don't need to go back in time. We just need to dig deep into the upper layer of our planet, crust. If we dig in the right spot, we can find these ancient remains. But, they don't look like animals or plants anymore. They have transformed into coal, or gas, or oil. We call these fossil fuels. And, we can burn them to get the energy we need. But, hold on. Let's rewind for a minute. There are a few mysteries to be solved here. How do these ancient animals and plants change to become solid coal, liquid oil, or even gas? Also, why are they found deep underground? Why not lying about in the surface? That certainly would make them much easier to find. Part of the answers to these questions is locked up in the time it takes for them to change. In fact, the true age of many of these animals and plants is older than the pyramids, older than the last ice age, and in some cases older than the dinosaurs. Let's look really closely, and find out exactly what happens to make them change, from a living thing, millions of years ago, to a fossil fuel today. The first thing to realize is that not all ancient animals and plants become fossil fuels. In fact, there are 4 different things that must happen to an ancient living thing in order for them to transform into a fossil fuel. We call these conditions. So, let's have a look at them. Let's examine them one at a time, and find out what they mean, beginning with this condition, the need for a saturated environment. But what does saturated mean? Imagine a sponge. Dip it in a sink, and, all of its tiny holes fill up with water. When the sponge cannot hold anymore, we say it's saturated. A perfect example of a saturated environment is a swamp. This time, let's have a look at the need for an anaerobic environment. But, what does anaerobic mean? Anaerobic sounds like a complicated word, but, it just means there is no oxygen around. There are lots of living things including you and me, need oxygen to survive. So, we live in places where there's lots of it. We call this an aerobic environment. However, some living things like certain types of bacteria like to live where there is no oxygen. This is called an anaerobic environment. A great example of an anaerobic environment is in a swamp. Up next, let's have a look at the need for high pressure. But, what really is pressure? Pressure is a force pushing down on or against something. A good example of a place with really high pressure is deep underground where there's lots of rock pressing down. The more rock, the more weight, and so the more pressure. And finally, the need for high temperature. So, what exactly is temperature? Temperature is the measure of how hot or cold a place is. Now we all know that the sun can make places hot on the earth. But, it's also very hot underground, beneath the earth's surface. This is because the earth produces its own heat. An example of a really hot place is in deep mines. Okay, let's recap. This means, for our ancient living things, to turn into fossil fuels, they need a saturated environment, anaerobic conditions, lots of pressure, and high temperatures. Let's watch the whole story now, from the ancient plants to a lump of coal. Tropical areas provide the ideal conditions for plant growth. Millions of years before the dinosaurs walked the earth, the land was covered with early types of plants, mainly ferns. In tropical areas, these ferns were huge, gigantic tree ferns. At this time in the earth's history, lots of changes were occurring across the planet. These changes caused the sea levels to rise, and flood the land, saturating the environment. As the water levels rose, small particles of soil and sediments were washed in. These gradually began to settle out to form a layer on the bottom. These changes transformed the area into a swamp, and overtime, it became more and more anaerobic. Without oxygen, the plants and trees died. Toppled over in layers, they were covered with water. Beneath the surface, in these anaerobic conditions, the plants however did not fully rot away, as oxygen is needed for things to properly decay. Gradually, layers of this plant material built up. And, then sediments continued to wash in, forming another layer on top, a bit like a sandwich. When the water levels eventually dropped, these sandwich layers left behind, were rich in nutrients; ideal conditions for new plants to grow. These plants, they grew big over many years, and the whole process began again. In fact, over millions of years, this process repeated over and over, like a cycle. So, in the formation of coal, ancient forests became flooded. And the rising water brought lots of sediments. These swampy conditions then became anaerobic, and caused the trees and forests to die. Layers of dead trees began to build up. And, they were covered by sediments, washed in with the rising water. In this anaerobic conditions, plants and trees could not fully rot. When water levels dropped again, layers of completely dead plants, buried under a layer of sediments were left behind, creating a perfect environment for new plants to grow. This process repeated over millions of years, and each time creating more sandwich-like layers of plants and sediments. As more and more layers piled up, the temperature and the pressure increased, pushing, squeezing, and heating the plant material to form coal. This process created layers of coal that we see today, when we dig underground in parts of Scotland.

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Duration: 9 minutes and 9 seconds
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Language: English
License: Dotsub - Standard License
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Views: 7
Posted by: pgtranscribes on Apr 4, 2015

7.Topic-2_Video-2

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