Question

discuss the distribution of oceans and continents. Pls ans in pointwise

Answer 1

CONTINENTAL DRIFT:-

By Alfred Wegener—a German meteorologist 1912. This was regarding the distribution of the oceans and the continents.According to Wegener, all the continents formed a single continental mass and mega ocean surrounded the same.The super continent was named PANGAEA, which meant all earth.The mega-ocean was called PANTHALASSA, meaning all water.He argued that, around 200 million years ago, the super continent, Pangaea, began to split.Pangaea first broke into two large continental masses as Laurasia and Gondwanaland forming the northern and southern components respectively.Subse-quently, Laurasia and Gondwanaland continued to break into various smaller continents that exist today.

 

Evidence in Support of the Continental Drift

The Matching of Continents (Jig-Saw-Fit)The shorelines of Africa and South America facing each other have a remarkable and unmistakable match.It may be noted that a map produced using a computer programme to find the best fit of the Atlantic margin was presented by Bullard in 1964.It proved to be quite perfect. The match was tried at 1,000- fathom line instead of the present shoreline.
 Rocks of Same Age Across the OceansThe radiometric dating methods developed in the recent period have facilitated correlating the rock formation from different continents across the vast ocean.The belt of ancient rocks of 2,000 million years from Brazil coast matches with those from western Africa.The earliest marine deposits along the coastline of South America and Africa are of the Jurassic age. This suggests that the ocean did not exist prior to that time.​
 TilliteIt is the sedimentary rock formed out of   deposits of glaciers.The Gondawana system of sediments from India is known to have its counter parts in six different landmasses of the Southern Hemisphere.At the base the system has thick tillite indicating extensive and   prolonged glaciation.Counter parts of this succession are found in Africa, Falkland Island, Madagascar, Antarctica and Australia besides India.Overall resemblance of the Gondawana type sediments clearly demonstrates that these landmasses had remarkably similar histories.The glacial tillite provides unambiguous evidence of palaeoclimates and also of drifting of continents.
 Placer DepositsThe occurrence of rich placer deposits of gold in the Ghana coast and the absolute absence of source rock in the region is an amazing fact.The gold bearing veins are in Brazil and it is obvious that the gold deposits of the Ghana are derived from the Brazil plateau when the two continents lay side by side.
 Distribution of FossilsWhen identical species of plants and animals adapted to living on land or in fresh water are found on either side of the marine barriers, a problem arises regarding accounting for such distribution.The observations that Lemurs occur in India, Madagascar and Africa led some to consider a contiguous landmass “Lemuria” linking these three landmasses.Mesosaurus was a small reptile adapted to shallow brackish water.The skeletons of these are found only in two localities : the Southern Cape province of South Africa and Iraver formations of Brazil.The two localities presently are 4,800 km apart with an ocean in between them.


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