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Did you know that Europe and North America are slowly moving away from each other, at the rate of about four centimetres per year? This movement seems far too slow to be of any importance, but over a period of millions of years, continents can move great distances across the surface of the Earth.
Until the early 20th century, scientists assumed that the locations of the continents were fixed.
But a young German scientist named Alfred Wegener began to question that assumption.
He noticed several facts that suggested the possibility that continents could move.
First, Wegener noticed that the coastlines of some continents seemed that they could fit together.
A good example of this is the west coast of Africa and the east coast of South America.
This suggested that these continents had long ago “broken apart” from each other.
Also, Wegener knew that some similar species of animals lived on continents that were very far apart.
This made him wonder if those species had once been a single species that lived in one homeland.
Those species would then have diverged when the continents divided.
In addition, Wegener found that some of the landforms on distant continents were quite similar.
For example, the rocks that make up the mountains of Scotland are similar to the rocks that make up the mountains of the eastern United States.
At first, Wegener’s idea was ridiculed by many scientists.
They thought that his theory of continental drift was absurd.
Part of the reason for this was that Wegener did not know how this movement of continents could happen. Unfortunately, Wegener died in 1930, at the age of 50, when he was on a scientific expedition to Greenland.
During the 1960s, scientists realized that Wegener had been right. New discoveries showed that the continents rested on top of giant “plates,” that could slide around the Earth, above a layer of molten rock.
Today, the idea of continental drift has been shown to be basically correct.
The movement of continents accounts for the creation of many mountain ranges, which rise when continents slowly collide. It also accounts for the creation of many valleys, which sink when continents slowly break apart. Continental drift also explains why the fossils of tropical plants and animals are sometimes found on islands in very cold places: those islands had once been located in warmer parts of the earth!
Wegener’s theory of continental drift was a revolutionary and radical idea. Eventually, however, this theory turned out to be correct. It is too bad that Wegener did not live to see the acceptance of this theory.