Earth and Moon

Continental drift

Continental drift

The phenomenon is called by which the plates that support the continents move over millions of years of the geological history of the Earth.

This movement is due to the fact that new material comes out of the mantle below the oceanic crust. Thus, a force is created that pushes the areas occupied by the continents (continental plates) and displaces them.

In 1620, the English philosopher Francis Bacon noticed the similarity of the forms of the western coast of Africa and eastern South America, although he did not suggest that the two continents had been united before.

The proposal that the continents could move was made for the first time in 1858 by Antonio Snider, an American living in Paris.

Wegener's theory

In 1915 the German meteorologist Alfred Wegener published the book "The origin of the continents and oceans", where he developed this theory, which is why he is usually considered the author of the Theory of continental drift.

According to this theory, the continents of the Earth had been united at some point in a single "supercontinent" which he called Pangea. Later Pangea had split into fragments that, because of the internal forces of the Earth, slowly moved away from their starting positions until they reached the ones they now occupy. At first, few believed him.

What made this idea acceptable was a phenomenon called paleomagnetism. Many rocks acquire at the time of forming a magnetic charge whose orientation coincides with that of the earth's magnetic field at the time of its formation.

In the late 1950s, this ancient and very weak magnetism (called "paleomagnetism") was measured with very sensitive instruments. The analysis of these measurements allowed to determine where the continents were when the rocks formed. It was shown that everyone had been united at some time in the past.

On the other hand, it baffles the fact that some botanical species and animals are found on several continents. It is unthinkable that these species can go from one continent to another across the oceans, but they could have easily dispersed by the time all the lands were united. In addition, rock formations of the same type and age are found in western Africa and eastern South America.

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The plates of the earth's crustContinuous movement