[PDF Notes] Essay on the Theories Involving the Displacement of Continents

These theories are based on the presumption that some 300 million years ago all the continents were joined together to form the super continent ‘Pangaea’. It was located at high latitudes far to the south of their present positions.

Although Pangaea was centered on the equator, its southernmost part included the South Pole. There was a rift in the Pangaea, and gradually it broke up into the separate continents that we know at present.

These continents drifted apart to occupy their present positions. Antarctica separated from Australia and slowly moved southward into its present position around the South Pole.

The continents of North America and Eurasia moved towards the North Pole. Brazil, Argentina, South Africa, India, Antarctica and Australia, where there are marks of glaciations, were then located in the high latitudes of the southern hemisphere.

This hypothesis, known as Wegener’s Continental Drift Theory, no doubt, solves many problems of geology, paleontology and climatology. The continental drift might have caused extensive temperature changes, even if the over-all climate of the earth did not vary appreciably.

However, this theory could not stand the rigorous test of geology. No force adequate enough to have rafted together the original Earth’s crust is known.

Similarly, geologists fail to understand the force which could break apart the super-continent and move its component parts to their present positions. The amount of movement required to account for the four glacial and four interglacial stages of Pleistocene ice age is out of question.

With the emergence of the Plate Tectonic Theory, the hitherto misunderstood Continental Drift Theory has regained wide support. This theory explains that the outer portion of the earth consists of several individual pieces called plates.

These plates move in relation to one another upon a partially molten zone below. Except the plate which covers the Pacific Ocean Basin, all other plates are made up of both continental and oceanic crust.

It is due to the movement of these plates that the continents shift their positions. It may be pointed out that the glacial features of present-day Africa, Australia, South America and India are not in harmony with the present climatic conditions.

These features give a clear indication of the ice age in geologic past. Now, the scientists are unanimously of the view that some 230 million years ago these regions must have experienced an ice age. At present it is hard to believe that climates in these regions located mostly in the tropical latitudes were like those found in Greenland and Antarctica.

According to the plate tectonic theory, all these regions having glacial features were joined together to make one universal continent called Pangaea. This super-continent was situated farther south from the present positions of its component parts.

Later on this super-continent broke apart. Each piece drifted towards its present position moving on a different plate. This revolutionary theory emerging from geology thus explains how large fragments of glaciated terrain reached their scattered subtropical locations.

Now, the geologists and other scientists believe that during the geologic past the continental drift must have brought about many more climatic changes. It must have radically changed the pattern of oceanic circulation leading to a corresponding change in the transport of heat and moisture.

Since the plates move at a very slow rate of only a few centimeters per year, significant changes in the positions of continents occur over large scales of geological time. Therefore large- scale climatic changes also happen in millions of years.

However, for explaining the short term climatic changes covering tens, hundreds or thousands of years, the plate tectonic theory is not helpful. Other explanations must be sought for explaining them.

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