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Continental drift theory
 

Continental drift theory

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    Continental drift theory Continental drift theory Presentation Transcript

    • Continental drift theory
    • According to the hypothesis of continental drift, continents have moved slowly to their current locations.
      Theory of continental was purposed by alferedwegner in (1912)
    • Mechanism for Plate Tectonics
      Seafloor Spreading provided insight to the mechanism for how the continents moved.
      The magma which pushes up at the mid-ocean ridge provides the new land pushing the plates, and the subduction zones gobble up the land on the other side of the plates.
      The mechanism was convection currents!
    • Thirteen plate on the world
    • About 225 million years ago , nearly all the land was united in one large land callled
      Pangaea
    • Pangaea about 200 million years ago, before it began breaking up. The southern portion of Pangaea Gondwana, and the northern portion Laurasia.
    • The continents about 70 million years ago. Notice that the breakup of Pangaea formed the Atlantic Ocean. India’s eventual collision with Eurasia would form the Himalayan Mountains
    • The position of the continents today. The continents are still slowly moving, at about the speed your fingernails grow. Satellite measurements have confirmed that every year the Atlantic Ocean gets a few inches wider!
    • Sea flour spreading
      As the seafloor spreads apart at a mid-ocean ridge, new seafloor is created.
    • Plate tectonic explain
      Earthquakes
      Mountains
      volcanoes
    • Earthquakes and volcanoes occur mostly along or near trenches and mid-ocean ridges...
    • Mountain formation
    • Volcanoes
    • Thawaearthequakeekkakdanna
    • Evidence to support the theory
    • Continental drift fossil evidence
    • “Puzzle Pieces”
      Continents look like
      they could be part of
      a giant jigsaw puzzle
    • Distribution of fossils of several organisms supported The theory that the continents were once joined together
    • Francis Bacon (1561-1626) first noted how coasts of Africa and South America fit.
    • Mesosaurus, a fresh water reptile that couldn’t swim across the open sea
    • Sequence of Rocks
      Same rock patterns found in South America, India,
      Africa, Antarctica and Australia
    • Mountains in South America and Antarctica are believed to have formed as part of the same mountain chain.
    • Ancient Climates
      Tropical plant remains (coal deposits) found in Antarctica
      Glaciations in Africa, South America, India, and Australia during the same time
    • Coal
      Deposits found inAntarctica.
      Coal requires a warm, lush climate ===>
      What’s Antarctica like today? ===>
    • Glossopteris, a seedfern whose seeds are too large to be carried far by wind
    • Fossils of Glossopteris are found in Permian rocks of South Africa, India, Australia, South America, and Antarctica—all regions that were once part of Gondwanaland.
    • Problems With The Theory
      • No mechanism for movement of continents
      • Wind and currents could possibly move fossils
      • Theory was not accepted by scientists