Discuss the geological evidences in support of Wegner theory?

 

 There are mainly five geological evidences, which support the Wegner theory, which are as follows: i. Similarities in Shape of Coastlines: The Atlantic coasts of South America and Africa have a roughly similar shape. They would fit in nicely if they are brought in contact with each other. However, the coastlines are not reliable geological features because there shape changes with rise and fall of sea level relative to the land. The real edge of the continent occurs at the continental slope where sea bottom flows rapidly down to deep ocean floor. The mapping of the continental slopes of eastern south America and west Africa has indicated that there contours match excellently. This strongly suggests that these two continents were once joined together.

 ii. Similar Orogenic Belt: If the eastern coast of South America and the western coast of Africa are fitted together, the orogenic belts of the two continents, which have the same range ages and similar structural trend, are found to align themselves across the join

. iii. Permo-Carboniferous glaciations: In the Parana basin in eastern Brazil (South Africa) glacial deposits of Permo- Carboniferous age are widespread. Their average thickness is about 600meters. The direction of ice movement suggests that the source area of these glacial deposits lies in south east of the present Brazilian coast. In southwest Africa, though the glacial deposits are meagre, there is abundant evidence for ice erosion. The direction of ice flow recorded is from east to west. This suggests that southwest Africa was covered by an actively eroding ice sheet which dumped its load further west in Brazil.

 iv. Paleomagnetic evidence: Igneous rocks record the earth’s magnetic field present at the time of their formation. A study of fossil magnetism in a region where several volcanic eruption had occurred on a widely separated occasions, has led to an interesting discovery. The orientation of the earth’s magnetic field in each of the separate lava flows is found to be different. This suggests that between volcanic eruptions, the magnetic poles have moved to a new location. Thus palaeomagnetic techniques, which locate the magnetic pole of any stage in the past, give consistent results on each continent only when they are placed in the proposed framework of the Gondwanaland. 

Animal And Plant Fossils: On the both sides of the south Atlantic, the fossil remains of Mesosaurus have been found. Nowhere else in the world, remains of Mesosaurus or other organisms were found on the continents of Africa and South America appears to link these landmasses during the Late Paleozoic and early Mesozoic eras. The remains of the “glossopteris flora” occur in the rock beds of the Gondwana series in South America, South Africa, India, Australia and Antarctica. These floras reached their maximum development in the Permo- Carboniferous period. The nature of their species distribution can only be explained if all the southern continents were joined together.