The Earth's InteriorPlate Tectonics Theory By Cindy Grigg 1 The earth's crust and the upper part of the mantle are known as the lithosphere. The lithosphere is solid and very firm, but it is not one whole piece. It is broken into sections called plates. There are eight major plates and some smaller ones. The places where these plates meet are called plate boundaries. 2 The plate tectonics theory explains how the continents drifted. It also explains how volcanoes, earthquakes, and mountains form. Plate tectonics is the study of the movement of Earth's crust. It's hard to imagine huge pieces of the earth's crust moving around, but they do. The movement is very small, though - only five to ten centimeters each year. What causes the plates to move? The simple answer is heat from inside the earth. 3 Under the lithosphere lies the asthenosphere. It is part of the earth's mantle. It is still solid, but it is much less firm. Geologists (scientists who study the earth) say that it has plasticity. It is soft because it is almost, but not quite, melted. This is magma, and it can flow like thick syrup. Geologists believe that the earth's plates move about on the asthenosphere like bubbles in a pan of hot water. Heat causes the magma to rise up in the mantle. When the molten magma meets the rigid material of the lithosphere, it moves across the surface horizontally. The magma begins to cool and sinks back down into the mantle. The cycle repeats. 4 The earth's landmasses and oceans sit on top of the tectonic plates. As the plates move, the oceans and continents ride on top of them. The plates move from side to side as well as up and down. The sides of plates may push together. They may pull away from each other. They may grind past each other in opposite directions. Over millions of years, the plates change in size and shape as the edges are added to, crash together, or pushed back into the mantle and melted. 5 Where two plates crash together, mountains are pushed up. This is how the Himalaya Mountains formed about 70 million years ago. Volcanoes and earthquakes occur at plate boundaries, too. The movement of tectonic plates changes the surface of the earth. Plate movements affect people and animals living on earth.Plate Tectonics Theory1. Plate tectonics is the study of ______.2. What causes the plates to move? Volcanoes Earthquakes Heat from inside the earth All of the above3. The plate tectonics theory explains ______. How the continents drifted The cause of volcanoes and earthquakes How mountains form All of the above4. Which layer of the earth is soft because it is almost, but not quite, melted? Core Mantle Lithosphere AsthenosphereEarth's Tectonic Plates By Cindy Grigg 1 Caption: This map from the U.S. Geological Survey shows earthquakes and volcanoes, represented by dots. Together, the dots show the boundary lines of the Earth's tectonic plates. 2 You may already know that the Earth has three main layers. We live on the crust of the Earth. The crust is the outermost layer. Even the oceans have a layer of crust under them. 3 Under the crust is the mantle. The mantle is made up of rock. It is not solid rock though. Inside the earth it is hot-hot enough to melt rock! The mantle is soft and fluid. It flows like melted plastic. 4 Under the mantle is the Earth's core. The core is very hot! 5 The crust is not a hard, solid piece. It is more like a jigsaw puzzle. There are pieces that fit next to each other. The pieces of the crust stay together. But they move about on the fluid, moving mantle. The pieces are called tectonic plates. The plates bump against each other like ice cubes in a glass. 6 You usually can't feel the Earth's plates moving. That's because the movement happens very slowly. Sometimes, people do feel when the earth's plates move. It's called an earthquake! 7 When plates move, three things can happen. First, they can pull away from each other in opposite directions. They can move toward each other and smash together. Or they can move past each other side-by-side. Because of these movements, volcanoes erupt. Mountains form. Earthquakes take place. 8 In the middle of the Atlantic Ocean, two plates are moving away from each other in opposite directions. Each year, the Atlantic Ocean gets about one inch wider. What do you think happens between the two plates as they pull apart? The hot, molten rock from inside the mantle of the earth oozes out. It's like a volcano erupting. New crust is formed at the bottom of the Atlantic Ocean. 9 In Asia, two plates are pushing against each other, like two goats butting their heads together. This pressure is pushing rock upward. The two plates smash against each other. This pressure formed the Himalaya Mountains. It took millions of years. The pressure of these two plates still pushing against each other is making these mountains taller all the time. 10 Two plates in California are moving past each other. One is going in a mostly northward direction. The other is moving in a southward direction. As they slowly grind past each other, pressure builds up. Sometimes it breaks loose. People in California feel an earthquake. 11 The Earth's crust is made up of about a dozen pieces called plates. The plates move in different ways. These movements cause earthquakes, volcanic eruptions, and mountain building. The movements of the Earth's tectonic plates change the surface of the Earth.Earth's Tectonic Plates1. The Earth's crust is compared to ______. A pie crust Dinner plates A hard boiled egg A jigsaw puzzle2. The mantle of the Earth is compared to ______. A hard boiled egg Melted plastic A jigsaw puzzle A pie crust3. Pieces of the Earth's crust are called ______. Mantle Tectonic plates Core Volcanoes4. Pieces of the Earth's crust can move in ______ ways. Three Four Many Two5. What happens when two plates pull away from each other in opposite directions? Mountains are made. Magma erupts and forms new crust. Earthquakes happen. All of the above6. What happens when two plates move toward each other and smash together? Mountains are made. Magma erupts and forms new crust. Earthquakes happen. All of the above7. What happens when two plates move past each other? Mountains are made. Magma erupts and forms new crust. Earthquakes happen. All of the above8. The movement of the Earth's tectonic plates does not change the surface of the Earth. False TrueThe Earth's Interior By Sharon Fabian 1 If you take an Easter egg, and dye it a swirly blue, green, and white, what would you have? 2 It might look like the earth, as we see it in photographs from space. Now, if you slice this little model of the earth in half, you can see the layers that it is made of. 3 The earth has an outside layer called the crust (the eggshell), an in-between layer called the mantle (the egg white), and an inner core (the yolk). 4 Just like the hard shell of an egg, the earth's crust is hard and solid. It is mainly rock. All of the earth that we can see, and walk on, and drive our cars on, is crust. And if you are at the beach and can't see any crust, because you are looking out at the ocean, it is still there under the water. The whole earth is coated with a thin (about 3 kilometers under the oceans, and about 19 kilometers under the land) layer of rocky crust. 5 The earth's middle layer, the mantle, is made up of molten, or melted, rock. The lava for volcanic eruptions comes from this layer. The dividing line between the mantle and the crust has a long and hard-to-say name; it is called the "Mohorovicic Discontinuity," but scientists call it the Moho for short. On the upper part of the mantle there are sections called tectonic plates. The seven continents sit on the top of these tectonic plates. 6 In 1906, the center of the earth, the core, was discovered by a scientist named R. D. Oldham. To make this discovery, he studied earthquakes, and also the ideas of a scientist from earlier times, Isaac Newton. The core consists mainly of iron, along with smaller amounts of other elements. The iron at the earth's core is partly solid, and partly liquid. Some scientists have a theory that the core is spinning on its own, much faster than the rest of the earth. 7 To learn about the earth's layers, scientists study earthquake waves, rock formations, and magnetism, but you can get a good picture of what they look like by studying a hard-boiled egg.The Earth's Interior1. Name the three layers of the earth. Shell, white, yolk Crust, mantle, core Crust, lava, core Continents, mantle, iron2. The "Moho" is the Tectonic plate Dividing line between the crust and the mantle Mantle Crust3. The earth can be compared to an egg because They are the same colors They were discovered by the same scientist They are made of the same materials They have the same three layers4. The core was discovered by R. D. Oldham Mohorovicic Isaac Newton5. The crust is _____ under the ocean than it is under the land. Thinner Thicker The same6. The idea that the earth's core is spinning at its own speed is A theory A fact Not true7. Why do you think scientists study earthquakes and rock formations to learn about the earth's layers?8. Why do you think the iron at the earth's core is partly liquid?Clues to Earth's Past By Cindy Grigg 1 How do scientists know what the Earth was like long ago? Scientists ask questions. They notice things. They gather clues and evidence. Then they make a hypothesis. They try to collect information to prove whether their hypothesis is correct or not. 2 In 1915, Alfred Wegener published his theory of continental drift. He said that all of Earth's continents were drifting. He thought that they could fit together. He carefully studied the outlines of the continents. He noticed that Africa and South America looked as though they would fit together like a jigsaw puzzle. He compared rock types from both sides of the Atlantic Ocean. He looked at fossils in the rock and found similar ones. How did the rocks and fossils get separated by the Atlantic Ocean? 3 Wegener believed that all of Earth's land masses were once joined into one giant landmass. He called it Pangaea, meaning "All Earth." Then, he said, Pangaea split apart. The different continents drifted away from each other, in time finding their modern places. 4 Wegener's ideas were not accepted at the time. He couldn't explain how the continents moved. In the 1950s and 1960s, other scientists found evidence for Wegener's theory of continental drift. They found fossils of a seed fern that had lived 250 million years ago. The same type of plant's fossils was found in South Africa, Australia, and India. Scientists believed the seeds of this plant were too big to have been carried across the ocean by wind. They could not explain how the plant could have traveled so far if the continents were in the same place then as they are now. 5 More fossil evidence was found. A hippo-like reptile left fossils in Africa, South America, and Antarctica. Scientists did not believe this animal could have swum the oceans between these land masses. 6 Rocks also supported Wegener's theory. The Cape Mountains of South Africa match the folded mountains near Buenos Aires, Argentina. It is very likely they were part of the same mountain range at one time. Similar rocks, deposited by glaciers, have been found in South America, Africa, India, Australia, and Antarctica. This would show that the same ice sheet may have once covered those places during one of the ice ages. In 1962, Harry Hess explained how the sea floor spreads and the continents move with it. Today Wegener's theory of continental drift is widely accepted. 7 Fossils are evidence of the plants and animals that used to live on the Earth. Scientists can date the rocks that fossils are found in. They can get a pretty good idea of how old the rock is and when the plant or animal must have been become trapped in the rock. 8 Another tool scientists use is DNA evidence. DNA is in the cells of every living thing. Changes in DNA over time create new adaptations and even new species. Scientists can compare the DNA of two different living things. They can get an idea of how closely related the two living things are (or were). DNA can only be gathered from living things, or sometimes, from soft body parts that have been preserved. These two things used together can give scientists a good picture of Earth's past.Clues to Earth's Past1. Alfred Wegener's theory of ______ said that all of Earth's continents were moving. Seafloor spreading Evolution of continents Continental drift The great rift2. Wegener's idea was thought to be true right away. False True3. Which of these did not support Wegener's theory of continental drift? Fossils of plants and animals found on different continents DNA evidence Similar glacial deposits found on different continents Similar rocks on different continents4. More than ______ years passed before Wegener's theory was supported by new evidence. Forty Fifty Thirty Twenty5. What did Wegener call Earth's one giant landmass?6. Why were Wegener's ideas not accepted at the time?The Earth's InteriorLabelLabel the Outer Layers of the EarthRead the definitions below, then label the outer layers of the Earth.Label Seafloor SpreadingRead the definitions below, then label the seafloor spreading (plate divergence) diagram.Lithosphere - the crust plus the rigid, upper mantle.Lower Mantle (semi-rigid) - the deepest parts of the mantle, just above the core.Magma - molten rock withing the Earth's mantle. In seafloor spreading, magma moves from the asthenosphere to the crust.Ocean - large bodies of water sitting atop oceanic crust.Oceanic Crust - thin parts of the Earth's crust located under the oceans.Oceanic Ridge - newly-formed region of the oceanic crust.Upper Mantle (rigid) - the uppermost part of the mantle, part of the lithosphere.Asthenosphere = Upper Mantle (flowing) - the lower part of the upper mantle that exhibits plastic (flowing) properties. It is located below the lithosphere (the crust and upper mantle).Theory of Plate TectonicsWrite the letter for the term that correctly completes each sentence in the space at the left_________Earth’s crust and upper mantle are broken down into sections called _____.a. lava b. plates2. ____Where Earth’s plates meet they may move past one another, pull apart, or _____a. collide b. divide3. The collision of one continental plate with another may produce ________.a. oceans b. mountains4. A rift valley can form where two continental plates are ______.a. moving apart b. forming5. New ocean crust is formed at a _________.Rift valley b. mid-ocean ridgeUse the following terms to complete a concept map. Cut and paste.RIFT VALLEYSDEEP-SEA TRENCHESTRANSFORMMAJOR EARTHQUAKESMID-OCEAN RIDGESVOLCANOESANDFORMFORMANDANDMOUNTAINS RANGES