Figure 2 – Pangaea

2.1.1. Evidences in Support of the Theory

A variety of evidences were offered in support of the continental drift theory. These are summarized as:

(a) 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 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.

(b) Rocks of Same Age Across the Oceans - 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. Similarly, Appalachian mountains of North America which come right up to the coast and then continue their trend across the North Atlantic Ocean in the old Hercynian fold mountains of South-West Ireland, Wales and Central Europe.

(c) Tillite - It 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. It clearly demonstrates that these landmasses had remarkably similar histories.

(d) Placer Deposits - The 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.

(e) Distribution of Fossils - 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. Such presence of identical plants and animals is possible only when they lived on a common landmass.

2.1.2. Forces for Drifting

Wegener suggested that the movement responsible for the drifting of the continents was caused by pole-fleeing force and tidal force. The polar-fleeing force relates to the rotation of the earth. This was, according to Wegener, the cause for movement of continents towards equator ward. Tidal force – due to the attraction of the Moon and the Sun – was the main reason given by Wegener for the westward movement of the Americas. Wegener believed that these forces would become effective when applied over many million years.