DMPQ: What is continental drift theory? Write down the evidence for continental drift?

The continental drift hypothesis was developed in the early part of the 20th century, mostly by Alfred Wegener. Wegener said that continents move around on Earth’s surface and that they were once joined together as a single supercontinent. While Wegener was alive, scientists did not believe that the continents could move. Alfred Wegener proposed that the continents were once united into a single supercontinent named Pangaea, meaning all earth in ancient Greek. He suggested that Pangaea broke up long ago and that the continents then moved to their current positions. He called his hypothesis continental drift.

 

  1. identical rocks of the same type and age are found on both sides of the Atlantic Ocean. Wegener said the rocks had formed side-by-side and that the land had since moved apart.Mountain ranges with the same rock types, structures, and ages are now on opposite sides of the Atlantic Ocean. The Appalachians of the eastern United States and Canada, for example, are just like mountain ranges in eastern Greenland, Ireland, Great Britain, and Norway. Wegener concluded that they formed as a single mountain range that was separated as the continents drifted.
  2. Ancient fossils of the same species of extinct plants and animals are found in rocks of the same age but are on continents that are now widely separated. Wegener proposed that the organisms had lived side by side, but that the lands had moved apart after they were dead and fossilized.
  3. Presence of glossopteris vegetation in carboniferous rocks of India, Australia, South Africa, Falkland Islands (Overseas territory of UK), Antarctica, etc. can be explained on the basis of the fact that parts were linked in the past.
  4. Tillite deposit: It is the sedimentary rock formed out of deposits of glaciers. The Gondwana 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.
  5. Rich placer deposits of gold are found on the Ghana coast (West Africa) but the source (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.

 

 

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