Continental Drift Theory
In 1912 Alfred Wegener (1880-1930) postulated that all the continents once were together forming a single continent. According to him, about 250 million years ago, the earth was made up of a single landmass called Pangaea (meaning "all lands"), and a single ocean surrounding it called as Panthalassa. Over a long period of time, probably 220 million years ago, they drifted apart and gradually moved to form their present position. First, Pangaea broke into two landmasses namely Laurasia in the north and Gondwana in the south.
Laurasia further split into Eurasia and North America. Gondwana land split into Africa, South America, Antarctica, Australia, and India.
Wegener put forward certain evidences to support the continental drift theory. Let us deal with it in detail.
The continental drift theory is supported by the following evidences.
· Certain identical rare fossils have been found in different continents.
· The fossils of Mesosaurus (a small Permian reptile), for example, have been found only in Africa and South America.
· The fossil of a Fern tree, about 360 million year old, has been found only in India and Antarctica.
· Rocks of similar type, formation, and age have been found in Africa and Brazil.
· Geological structure in Newfoundland matches with that of Ireland, Scotland and Scandinavia. Geological Structure of Appalachian Mountains matches with Morocco and Algeria in North Africa.
· The corresponding edges of the continents fit together. For example, the western side of Africa and the eastern side of South America fit together.