Geology 2 - Geology Plate Tectonics: 1. Unifying theory of...

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Geology Plate Tectonics: 1. Unifying theory of the Earth 2. Greatest Revolution in the Earth Science “Central theory of earth” “whole theory of how earth works” Plate Tectonics: - This is unique to earth compared to other planets in the solar system - This theory arose out of the need to explain incontrovertible evidence for continental drift that had been occurring through geological time - Evidence that was not taken seriously until the discovery of the mechanism that makes continental drift possible sea-floor spreading Theory it has passed test –may be redefined Alfred Wegener (1880-1930) “meteorologists /climatology” not geologist. Wegener saw the Earth as a complex system and to see earth as a whole we need to be able to work with different branches of science “not just looking at a rock”! - Worked for German meteorologist service - He said to hypothesize first then theorize was the best method - Late 1920’s published the book “Our Wondering Continent” - Tragedy in Greenland Continental Drift Fit of continental margins – proves continental drift- by looking at the map you can see where they fit in “like a puzzle” Wegener’s (1920) reconstruction of Pangaea- correct by today’s standards! Not only a possible 250 Ma years ago - Laurasia : northern land mass of Pangaea that separated first from southern land mass - Gondwana: Southern land mass
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Proofs- Distribution of Upper Paleozoic (350-250 Ma) Fossils in the Southern continent (Gondwana) [DuToit & Wegner] it is not a coincidence that DuToit was form South Africa because it is easier to see the evidence for continental drift. <Mesosarus fossils only found in Africa and Argentia> all the same age <Tystosarus found in India, Africa, Antarctica> <Cynogashus- mammal like reptile South America, Africa> <Glossporis fern tropical plant> Distribution of Upper Paleozoic (350-250 Ma) glacial features in the Southern Continents (Gondwana) sediment deposited by a glacier – ice doesn’t have any restrictions so moves anything. Sediment not rounded like when carried by wind, when carried by ice on the top or in ice it is jagged shaped. Whenever glaciers move over bed of rock they form well marked groves- these scratches tell what direction they are moving. So by looking at the direction of the groves we join the continents together and move Africa and others to make a certain point in Africa to be on the South Pole because of the huge land mass that must have existed due to ice spreading and not floating. Distribution of Rain Forest Swamps and deserts equator- rainforest after they die and decay fossils form coal (350- 250 Ma) Dismembered Mountain Chains {Caledonides- roman name for Scotland} N.America, Africa, Greenland, Britain, etc. Similarties in rock types and ages
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Geology 2 - Geology Plate Tectonics: 1. Unifying theory of...

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