WHY CONTINENTS AND OCEANS STARTED TO MOVE?
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UNIFICATION OF EARTH |
HISTORICAL BACKGROUND
The Unification of the continents and oceans are not a new concept.The Scientists and Scholars wondered about the shape of the south america and Africa More than 400 million years ago,many scientist started to think about the earth's positions.If South america and Africa come to together ,it fits perfectly.ABRAHAM ORTELIUS in 1596 first talked about the positions of the continents and oceans.Following by him sir FRANCIS BACON in 1620 and ANTONIO SNIDER in 1858 gave the idea of unity of the earth,However it was in 1908, F.B.TAYLOR, postulated his concept of "HORIZONTAL DRIFTING OF CONTINENTS". In 1912 ALFRED WEGENER gave his theory on drifting of continents.
ALFRED WEGENER'S CONTINENTAL DRIFT THEORY
Wegener's theory was mainly based on the problem solving theory.Before wegener,there are numbers of concepts ,works and findings. Wegener assumed that the climatic change might be related to it because there are various evidences that related to the climate change.In fact ,"The continental drift theory grew out the need of explanation the major variation in climate in past"
ROLE OF CLIMATE
- Continents remains stationary at their place and climate shifts from one place to other.
- The climatic zone remains stationary and the continents moves.
MAIN CONCEPT:
Wegener said that all continents could be united together in a form of super continents.He believed that earth crust made of SIAL and SIMA continents are floating into ocean.He said that the continents are together in united form called as PANGEA which means " all land".and the ocean around pangea called PANTHALASSA.
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| PANGEA AND PANTHALASSA |
DRIFTING OF CONTINENTS ACCORDING TO GEOLOGICAL TIME SCALES
- In Carboniferous era the south pole was near the south Africa coast and the pacific ocean in north pole.
- In Mesozoic era Pangea started to split into two proto continents i.e LAURASIA and GONDWANA. Laurasia consisted of North america,Europe,Greenland,and Asia excluding India. Gondwana in southern continents consisted of India,South america ,Africa and Australia.
- By the end of Cretaceous era,the continents were seperated into landmasses and form present day continents.
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| DRIFTING OF PANGEA ACCORDING TO GEOLOGICAL TIME SCALE |
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wegener assumed the continents were moved horizontally on seafloor .due to movement of the continents ,the folded mountain formed.
WHY CONTINENTS WERE MOVED?
Wegener started that there must be some mechanisms that drifted the continents.he stated that the ocean is being lesser materials situated below the heavier materials.therefore two mechanisms that moved to help the continents was
- Centrifugal Force : wegener believed that the centrifugal forces which creates the spinning of the earth on its own axis.the breaking of continents in past was caused of centrifugal force and pushed continents towards the pole
- Tidal Force: tidal forces are causing of the movement of continents towards westward.
