Continental Drift Theory

Continental Drift Theory

Continental drift theory proposed by Wegner explains the horizontal displacement of continents and oceans. According to this theory, there was a time when all the continents of the world were joined together as a single landmass. This single landmass got fractured around Carboniferous period into various different landmasses and got drifted away from each other.

Wegner gave the name Pangea to the super-continent which was the only single landmass. Although it was a single landmass, it was considered to be of two parts: Lauratia- the northern block and Gondwanaland- the southern block. Between these two blocks, a shallow sea named Tethys is said to be situated. The Pangea was surrounded by an extensive ocean that has been named Panthalasa.

The continental landmass of Pangea consisted low density sialic matter (silicon and aluminium) and the sea Panthalasa surrounding Pangea consisted of high density simatic matter (silicon and magnesium).

According to Wegner, the single landmass got fractured into different blocks under the influence of differential forces i.e. gravitational and tidal forces before Carboniferous period. Then they started drifting away from each other under these forces. The present day oceans have occupied the spaces between the drifted away land blocks called continents. The advancing edges of the continents got folded due to the obstruction caused by the bottom of the ocean. In some area, Fold Mountains have formed due to this reason.

There are mainly two facts supporting this theory:

1. Fossil evidence: The fossils collected from the different continents supports the fact that earlier these continents where joined together to form the single landmass.
2. Structure of blocks: It has been found that if the continents on the eastern and western sides of the Atlantic Ocean are brought together, then they fit into each other like the pieces of a jigsaw puzzle.

Despite of the various reasoning and evidences supporting the theory, this theory was rejected as it was not able to answer certain questions. Displacement of higher density simatic ocean bottom by lower density sial (continents) has been questioned. Also, the differential forces are not strong enough for the horizontal drifts.