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Plate tectonics theories.pptx POWERPOINT
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- 4. The Theories ofPlate Tectonics BASED ON TWO HYPOTHESES Continental Drift Theory Seafloor Spreading and Subduction Theory PLATE TECTONIC THEORY
- 6. Alfred Wegener proposed thehypothesis of continental drift in 1911 He gathered information from many different sources and used it as evidence for his hypothesis Continental Drift Hypothesis
- 7. Continental Drift theory(Alfred Wegener) (Oskin, 2017) - supercontinent called Pangaea two sub-continents, Laurasia and Gondwanaland. Laurasia split into a few smaller continents forming the continents in the northern hemisphere of the Earth. -Asia, Europe and North America southern hemisphere, South America, India, Africa Australia and Antarctica, are the two continents divided from Gondwanaland.
- 8. Continental Drift Hypothesis Glaciersformed at the south pole Swamps formed in tropical regions Fit of the continents Fossil evidence Ancient mountain ranges Past climate evidence
- 9. The continental drift hypothesisproposes that the continents were assembled to form the super continent Pangaea. Moved through time
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- 11. Antonio Snider-Pelligrini (1858),a geographer cut out a map of Africa and South America suggesting they were connected at one time Other physical evidence based on observation was used by Wegener Fit of Continents
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- 13. Fossil Evidence Similarterrestrial species were found on many continents now separated by oceans. Information collected by paleontologists
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- 15. Ancient Mountain Ranges Thesame sequence of rocks is found in North America, Great Brittan, and Norway. The pattern does not make sense with the continents in their current configuration.
- 16. The Appalachian Mountains Swamps 300million years ago
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- 18. Evidence of PALEOCLIMATE DATA •Glaciers carve(STRIATIONS) the rock as they move. •Scientists can determine the direction of movement (notice the direction of movement noted in South America) •As South America sits today, the pattern would not make sense. (glaciers do not move from sea level to higher elevations)
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- 20. Lack of mechanismto explain continental movement. Evidence implied that the continents were at one time assembled Wegener’s idea was not accepted by the scientific community because he could not explain how the continents moved With advances in technology, new information was gathered
- 22. Seafloor Spreading and SubductionTheory Seafloor Spreading Theory (www.divediscover.whoi.edu) - Proposed by Harry Hess of Princeton University and Robert Deits - States that the seafloor is continuously spreading and the extra crust gets recycled into the mantle through subduction
- 23. Driving Mechanisms Convection current withinthe mantle Pushing at the mid- oceanic ridges Pulling at the subduction zones Push Pull Convection
- 24. How is seafloorspreading theory and continental drift theory related?
- 25. • Seafloor spreadingexplains how the continents moved apart Seafloor spreading, along with the continental drift theory, became part of the theory of plate tectonics.
- 26. Additional Information ocean floorwere much younger than those found on the continents. The youngest rocks were those nearest the underwater ridge system which is a series of mountains that extend around the world, stretching more than 64 thousand kilometers (40 thousand miles).
- 27. Plate Tectonics Theory PlateTectonics Theory (www.ck12.org; Oskin, 2017) - States that the crust is composed of different plates which move either towards, away or past each other. - The modern version of the Continental Drift Theory of Alfred Wegener
- 28. Important concepts inthe theory of plate tectonics include the following: 1.The ocean floors are continually moving — spreading from the center, sinking at the edges, and being regenerated. 2.Convection currents beneath the plates are responsible for plate movement. 3. The source of energy responsible for generating the heat and convection currents that move the plates is most likely radioactivity deep in Earth's mantle.
- 29. EXPERIMENT MATERIALS 2table spoon cornstarch Dropper Spoon Glass or plastic cup Oil 200ml Food color Match/lighter Water 100 ml Denatured gas