Describe the continental drift theory of Wegener.
In 1912 Alfred Wegener proposed the Continental Drift Theory. The basic concept regarding continental drift was that all the continents of today formed a single continental mass — a Super Continent. This was surrounded by a mega ocean. PANGAEA is a Greek word which means all earth.
He argued that around 200 million years ago the super continent Pangaea began to split. It was first broke into two large continental land masses —
1. Laurasia in the Northern Hemisphere,
2. Gondwanaland in the Southern Hemisphere.
These two continued to break apart into the various smaller continents that exist today. A number of evidences were there in support of the Continental Drift Theory :
1. The matching of the continents : The shore lines of Africa and South America facing each other have a remarkable and unmistakable match.
2. Rocks of the same ages across the oceans : The belt of ancient rocks of 2000 million years from Brazil coast matches with those from western Africa.
3. Placer deposits : Discovery of rich deposits of Gold in the Ghana and the complete absence of source rock in the region has left in scientists wondering. The location of gold bearing veins are in Brazil and make it obvious that the gold deposit of Ghana are derived from Brazil.
4. Distribution of Fossils : The identical species of plants and animals adapted to living on land or in fresh water are found on either side of the marine barriers.
5. Tillite : Tillite are sedimentary rocks formed out of deposits of glaciers. Gondwana system of sediments from India is known to have its counterparts in six different land masses of Southern Hemisphere.
