Question

Discuss the limitations of Continental drift Theory given by Wegner. Explain, how Plate Tectonic Theory is an improvement over it.

Answer 1

Approach:

1. Discuss Continental drift Theory given by Wegner.
2. Write an argument against the concept.
3. Add a few points on plate tectonic theory.
4. Conclude with how plate tectonic theory is an improvement over Continental drift Theory given by Wegner.

Continental drift was a theory that explained how continents shift position on Earth's surface. Set forth in 1912 by Alfred Wegener, a geophysicist and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents.Wegener thought all the continents were once joined together in an "Urkontinent" before breaking up and drifting to their current positions. But geologists soundly denounced Wegener's theory of continental drift after he published the details in a 1915 book called "The Origin of Continents and Oceans." Part of the opposition was because Wegener didn't have a good model to explain how the continents moved apart. Serious doubts have been raised about the period during which the forces causing the drift had operated and also about the direction and amount of force.

Some other limitations are as follows:

• The mechanism suggested by Wegener for the displacement of continental blocks did not withstand criticism. According to him, tidal forces due to lunar-solar attraction and the forces of the earth’s rotation were responsible for the drifting of the continents. But it was difficult for geologists to conceive of a driving force that could move continents. Sir Harold Jeffreys demonstrated that the forces suggested by Wegener to have caused the drift were either ineffective or inadequate for such movements.
• The fit suggested is hardly perfect and cannot be expected to be real since erosion along the coast lines through long geological ages must have modified them considerably.
• Fossil plants could have been spread from one continent to another by winds or ocean currents. Similarity of fossils occurring in more than one continent need not signify that the continents were all joined as one, sometimes in the past.
• R.T. Chamberlain has pointed out that the petrographic analysis of the rocks on either side of the Atlantic shows that their resemblance is only superficial.
• Bailey Willis (1928) has pointed out that the forces which were great enough to have built the Andes Mountains, would almost certainly have deformed South America to such an extent that any similarity of its eastern coastlines facing Africa would have been destroyed and the drifting is quite unlikely.
• Polar-wandering might have been caused by moving poles rather than by moving continents.

Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. Wegener didn't have an explanation for how continents could move around the planet but plate tectonic theory clearly explains this mechanism. This theory is identified to be par excellent approach to facilitate understanding of development process, development location of second order relief features it avails explanation of development mechanism of older relief features in the context of recognising dynamic locational characteristics of the plate boundary and concept of uniformitarianism. So we can say that Plate tectonic theory avails recognition to Wegener’s continental drift theory and an improvement over it.