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Transcript of Earth Science
Explore the processes that led to formation of sedimentary rocks and fossil fuels. The surface of the Earth is always changing! One of the ways we can learn about our Earth is by studying rocks and the changes that may have happened to rocks over time. Sedimentary rocks are formed from sediment that is deposited after being weathered and eroded from other rocks. The deposited sediment is pressed together over time to form new rocks. These are a few examples of sedimentary rocks. Limestone Quartz Sandstone Quartz Sandstone Gypsym Conglomerate Sandstone Sedimentary rocks form layers as they are deposited and pressed together. The older layers of rock are on the bottom and the newer layers of rock are on the top. This cliff at Zion National Park in Utah shows very distinct layers of sedimentary rock. The rocks are different colors depending upon what type of sediment was deposited. Most of the red and yellow rocks are sandstones. The gray layer is a type of sandstone called graywacke. In this formation, the graywacke is from the late Triassic period about 210 million years ago, in which dinosaur footprints have been found. The upper layers of the rocks were deposited about 10 million years ago. The lowest layers of rocks were deposited over 250 million years ago. Sedimentary rock contains some very useful resources called fossil fuels. Fossil fuels are found inside sedimentary rock deep underground in regions that used to be oceans or swamps millions of years ago. Fossil fuels are made from organic material. Organic means that it was once living. The organic material that make up fossil fuels are microscopic animals and plants that died millions of years ago. When the microscopic animals and plants died, they sank to the bottom of the ocean or swamp and were eventually buried under sediment. The weight of more sediments on top of the layer of organic sediment creates pressure that generates heat. MILLIONS
Years Organic sediment
takes to convert into fuel! The main ingredients
for the creation of
fossil fuels are: organic material pressure heat millions of years There are three main types of fossil fuels:
COAL, OIL, and NATURAL GAS. Formation of COAL Coal is a fossil fuel formed from dead plant material. Between 280 and 345 million years ago, plants in swampy areas died and sank to the bottom of the swamp. Underwater, in the absence of oxygen, they did not decay but got compressed by the weight of more dead plants and sediment on top of them. Over millions of years, this formed peat (brown layer). When near the surface, the coal can be extracted by mining. Coal Mine Coal Power Station More sediment layers increased the pressure and changed the peat into coal (black layer). Formation of OIL Oil is a fossil fuel which forms over millions of years from organic remains. It is thought that the process starts when large amounts of dead plankton formed a layer on the seabed. Over millions of years, layers of sediment built up on top of this organic layer, compressing and heating it until the organic material turned into oil. The oil is lighter than the surrounding rocks and filters upwards accumulating in a reservoir where a drilling platform mines it. Oil platforms are used to drill and pump oil from below the Earth's surface, often from below the seabed. Oil can be pumped from deep underground in regions that used to be oceans or swamps millions of years ago. Crude oil is what comes out of the ground before it has been processed. Formation of NATURAL GAS Natural gas is one of the world's three main fossil fuels. It is a gaseous mixture, consisting mainly of methane, found in the Earth's crust. Natural gas is moved by pipelines. It is stored along the way in large storage systems. When chilled to very cold temperatures, natural gas changes to a liquid and can be stored this way as well. Slightly more than half of the homes in the United States use natural gas as their main heating fuel. Natural gas is also used in homes to fuel stoves, water heaters, clothes dryers, and other household appliances.