1. In 1915, the German-born Alfred Wegener published the Continental Drift Theory, proposing that 200 million years ago all the emerse masses of the Earth were gathered together as a sole supercontinent, called Pangaea, encircled by an universal sea, the Panthalassa. Later, this continental mass split into smaller parts, which, by degress, moved away from each other as a consequence of the horizontal movements. Besides the similarity shared by the borders of all continents, which fit into one another as a big jigsaw puzzle, Wegener searched for geologic, paleontological and climatic evidences, particularly in the continents of the southern hemisphere, to validate his hypothesis.

Pangaea

 

He believed that the force to generate the movement of the continents would have derived from the tides and the rotation of the Earth itself. Although, there are some difficulties, both of a physical and a mathematical nature, in supporting this theory for the Pangaea's movement. Thus, the theory suffered a strong opposition from the main scientists at the time, something which almost cast it into oblivion.

Wegner's Theory

 

The great scientific revolution happened in the 60's with the obtaining of countless new information, particularly in the Geology field and the marine geophysics: a better understanding of the bottom of the sea bed; development of the paleomagnetism and of the concept of the transform faults; a more accurate definition as to the source of the earthquakes, etc. Out of these ideas, between 1967 and 1968, came into being the Plate Tectonic Theory, with the works of J. Morgan, X. Le Pichon and D. McKenzie, among other author