Plate Tectonics Lecture Chapter 2
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Plate Tectonics Lecture Chapter 2



continental drift

continental drift



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    Plate Tectonics Lecture Chapter 2 Plate Tectonics Lecture Chapter 2 Presentation Transcript

    • Plate Tectonics Mr. McKay Earth Science
    • Drifting Continents
      • Evidence of drifting
        • Fossils found on both of the continents of Africa and South America that are of the same organism
          • Fossils: The preserved remains of ancient organisms
        • German scientist Alfred Wegner came up with the theory of continental drift , he was actually a meteorologist and not a geologist
          • The theory called the giant landmass that once was on Earth Pangaea
            • Pangaea : Means all Earth
      • Early Earth & Plate Tectonics
    • Fossil Evidence
      • Fossils play a key role in supporting the theory of Continental drift
        • Glossopteris is an extinct plant
          • They are found in rocks that are around 250,000,000 years old ( 250 million)
          • The seeds were to large to be carried by wind and too fragile to have survived ocean waves
          • The fact that they are found in Antarctica implies that they had to be in a better climate than what is present Antarctica
    • Fossils
      • Glossopteris: a fern found on the southern continents
      • Cynognathus: a land reptile found in South America and Africa
      • Lystrosaurus: a land reptile found in Africa, Antarctica, and India
      • Mesosaurus: a freshwater swimming reptile found in Africa and South America
    • Fossil Evidence
      • From Rocks
        • Not only fossils provide evidence for theory support
          • Rocks in Africa and South America
            • When you examine the continents from these two they look as if they could piece together like a puzzle
            • The layers of coal depth line up with each other
            • Rock deposits from glaciers also match
    • Divergent Boundary
      • Divergent Boundaries
        • Constructive-add new land
        • Mid-ocean Ridge
          • Ocean floor moves away on either side of the ridge
          • Called sea-floor spreading
          • Often offset by transform faults which causes a curve in the ridge
      Transform Faults Sea-Floor Spreading/Mid-Ocean Ridge Spreading Sea Floor Basic Plate Boundaries
    • Magnetic Rock Strips
      • Some minerals have magnetic properties
      • These minerals line up with the Earth’s magnetic poles
      • When the molten rock hardens, a permanent record of the Earth’s magnetism remains
      • The Earth’s magnetic poles have reversed themselves from time to time
      • Animation
      • Sea Floor Spreading
    • Convergent Boundaries
      • Plates collide-destructive
      • Two continents colliding build mountains or plateaus
      • The Indian Plate and the Eurasian Plate collide to form the Himalayas which have Mt. Everest , the highest mountain on Earth.
    • Convergent Boundary
      • Destructive-crust is destroyed (melted by the mantle)
      • Called Subduction
      • When oceanic and continental crust collide
      • Oceanic crust is pushed down into the mantle and melted
      • Some of this melted material surges upward
      • The continental crust is also forced upward producing volcanoes
      • The Cascade Range in Washington and Oregon are an example of this
      Convergent Boundaries Convergent Boundaries
    • Convergent Boundaries
      • When two oceanic plates collide subduction occurs
      • The older denser plate is pushed into the mantle and melted
      • Some of the material rises upward and erupts on the ocean floor forming an island arc
    • Theory of Plate Tectonics
      • Tectonics: refers to the branch of geology that is concerned with plate movements
      • Theory of Plate Tectonics: Links together the ideas of continental drift and ocean floor spreading to explain how the Earth has evolved over time.
        • It explains the formation, movements, collisions, and destruction of the Earth’s crust
        • According to the theory the Earth’s uppermost layer, called the lithosphere, is made up of plates
    • Lithospheric Plates
      • There are seven major plates
        • The Pacific Plate-
          • which covers 1/5 of the Earth
        • North American
        • South American
        • Eurasian
        • African
        • Indo-Australian
        • Antarctic Plates
      • There are also Many smaller plates
        • Caribbean
        • Arabian
      • Plate Tectonics Review