Plate Tectonics
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Plate Tectonics

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Plate Tectonics Plate Tectonics Presentation Transcript

  • Tectonics Plate T- 1-855-694-8886 Email- info@iTutor.com By iTutor.com
  • Plate Tectonics  The Earth's crust is made of pieces of rock called tectonic plates.  Plate tectonics is the study of how the Earth's crust is shaped by geological forces. It relies on the understanding that the crust is divided into large pieces, or plates, that sit on the molten interior of the planet.  The theory was formulated in the 1960s and 1970s as new information was obtained about the nature of the ocean floor, Earth's ancient magnetism, the distribution of volcanoes and earthquakes, the flow of heat from Earth's interior, and the worldwide distribution of plant and animal fossils © iTutor. 2000-2013. All Rights Reserved
  • Structure of the Earth  The interior of the Earth is divided into layers based on chemical and physical properties.  The Earth is made up of 3 main layers:  Core  Mantle  Crust  The Earth has an outer silica-rich, solid crust, a highly viscous mantle, and a core comprising a liquid outer core that is much less viscous than the mantle, and a solid inner core. Inner core Outer core Mantle Crust © iTutor. 2000-2013. All Rights Reserved
  • Structure of the Earth The Crust  This is where we live!  Outermost layer  5 – 100 km thick  Made of Oxygen, Silicon, Aluminum  The Earth’s crust is made of:  Continental Crust thick (10-70km) buoyant (less dense than oceanic crust) mostly old  Oceanic Crust thin (~7 km) dense (sinks under continental crust) young © iTutor. 2000-2013. All Rights Reserved
  • Pangaea  Alfred Wegener was a German climatologist and arctic explorer who suggested the concept of continental drift.  Continental drift is the idea that the continents move round on Earth’s surface.  Wegener thought that the continents we know today had once been part of an earlier supercontinent.  He called this great landmass Pangaea. © iTutor. 2000-2013. All Rights Reserved
  • Movement Of Continents  The surface of Earth is broken into many pieces like a giant jigsaw puzzle.  Plate tectonics describes how these pieces move on Earth’s surface. © iTutor. 2000-2013. All Rights Reserved
  • Evidence For Continental Drift  Wegener’s belief was a scientific hypothesis based on observations.  Continental drift was accepted by all scientists because there was no evidence at the time to explain how continents could move. © iTutor. 2000-2013. All Rights Reserved
  • Evidence For Continental Drift  Coal beds stretch across the eastern U.S. and continue across southern Europe.  Matching plant fossils are found in South America, Africa, India, Australia, and Antarctica.  Matching reptile fossils are found in South America and Africa.  Matching early mammal fossils are found in South America and Africa.  Fossils in South America and Africa are found in rocks of identical age and type.  Matching rock types and mountain belts occur in North America and the British Isles, and Africa and South America.  Evidence of glaciers is present in regions with warm, dry climates. Continents that are close to the equator today were once closer to the South Pole in the distant past. © iTutor. 2000-2013. All Rights Reserved
  • Map With Fossil Reaction © iTutor. 2000-2013. All Rights Reserved
  • Sea Floor Spreading  American geophysicist Harry Hess helped develop the theory of plate tectonics.  While a Navy officer, Hess helped map the ocean floor. © iTutor. 2000-2013. All Rights Reserved
  • Undersea mountains  Naval maps showed undersea mountain chains that formed a continuous chain down the centers of the ocean floors.  Hess wondered if new ocean floor was created at these mid-ocean ridges. © iTutor. 2000-2013. All Rights Reserved
  • © iTutor. 2000-2013. All Rights Reserved
  • Sea Floor Spreading Hypothesis  Hess called his hypothesis sea-floor spreading.  The key was the discovery that there are “magnetic patterns” in the rocks on either side of the mid- ocean ridges.  Matching magnetic patterns and the age of rocks on either side of mid-ocean ridges provided strong evidence for sea- floor spreading. © iTutor. 2000-2013. All Rights Reserved
  • Moving Pieces Of The Lithosphere  Scientists realized that large pieces of Earth’s surface moved about like rafts on a river.  These “rafts” are pieces of lithosphere called lithospheric plates.  Plate tectonics is the study of these lithospheric plates.  There are two kinds of lithospheric plates:  Oceanic plates and Continental plates. © iTutor. 2000-2013. All Rights Reserved
  • What Drives Lithospheric Plates?  Convection cells in Earth’s lower mantle drive the lithospheric plates on the surface.  Heated lower mantle material rises toward Earth’s surface.  Cooling makes the nearby material denser and it sinks deeper into the lower mantle.  This sinking process is called subduction. Rising convection current Mid – ocean ridge Lithosphere Convection cell in the mantle subduction © iTutor. 2000-2013. All Rights Reserved
  • Hot Spots And Island Chains  If the eruption is strong and lasts long enough, the volcanic eruption may form an island on the plate.  After the island forms, the movement of the plate carries it away from the mantle plume.  Scientists determine the direction and speed of plate movement by measuring these island chains.  A single hot rising plume, called a mantle plume, can cause a volcanic eruption in the plate above it. © iTutor. 2000-2013. All Rights Reserved
  • Hot Spots And Island Chains © iTutor. 2000-2013. All Rights Reserved
  • The End