INTRODUCTION

The continental drift hypothesis was occurred in the early part of the 20th century, mostly by Alfred Wegener. Wegener claimed that continent move approximately on Earth’s surface and also that lock were once joined with each other as a single supercontinent. If Wegener to be alive, researchers did not think that the continents might move.

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THE continental DRIFT IDEA

Find a map of the continents and also cut each one out. Better yet, use a map wherein the edges of the continents display the continent shelf. That’s the true size and also shape that a continent. Can you fit the piece together? The easiest attach is between the eastern Americas and western Africa and also Europe, but the rest can fit with each other too (figure 1).

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api/deki/files/1204/CD_Figure_2.png?revision=1&size=bestfit&width=486&height=158" />Figure 2. The similarities between the Appalachian and also the eastern Greenland mountain ranges are evidences because that the continent drift hypothesis.

ancient fossils that the same types of die out plants and animals are uncovered in rocks that the same age but are top top continents the are now widely be separated (figure 3). Wegener proposed the the organisms had lived side by side, but that the lands had actually moved apart after ~ they to be dead and fossilized. He said that the organisms would certainly not have been able come travel across the oceans. Fossils that the particle fern Glossopteris were too hefty to be lugged so far by wind. Mesosaurus was a swimming reptile but could just swim in fresh water. Cynognathus and also Lystrosaurus were land reptiles and also were unable to swim

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Figure 3. Wegener used fossil proof to support his continental drift hypothesis. The fossils of this organisms are discovered on lands that are now far apart.

Grooves and also rock deposits left by old glaciers are discovered today on different continents an extremely close to the equator. This would show that the glaciers either created in the middle of the ocean and/or covered most of the Earth. Now glaciers only kind on land and nearer the poles. Wegener thought that the glaciers were centered over the southern land fixed close come the south Pole and the continents moved to their present positions later on on. Coral reefs and also coal-forming swamps are uncovered in tropical and also subtropical environments, but ancient coal seams and coral reefs are uncovered in locations where that is lot too cold today. Wegener suggested that these creatures were alive in warmth climate zones and that the fossils and coal later had actually drifted to new locations on the continents.

Take a look at this computer animation showing the Earth’s climate belts remain in about the same place while the continent move and this animation showing how the continents split up.

Although Wegener’s evidence was sound, many historicsweetsballroom.comlogists at the time rejected his theory of continental drift. Why carry out you think they did not accept continental drift?

Scientists suggested that there was no method to explain how solid continents could plow v solid oceanic crust. Wegener’s idea was virtually forgotten until technical advances gift even much more evidence the the continent moved and also gave researchers the devices to develop a device for Wegener’s drifting continents.


MAGNETIC POLARITY EVIDENCE

Puzzling brand-new evidence came in the 1950s from researches on the Earth’s magnetic background (figure 4). Scientists supplied magnetometers, devices capable of measure the magnetic field intensity, come look in ~ the magnetic properties of rocks in numerous locations.

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api/deki/files/1207/CD_Figure_5.png?revision=1&size=bestfit&width=429&height=305" />Figure 5. Earth’s current north magnetic pole is in north Canada.

enlarge rocks that are the very same age and also are situated on the very same continent suggest to the same location, yet that place is not the current north magnetic pole. Older rock that are of different ages perform not point to the same areas or to the current magnetic north pole.

In various other words, return the magnetite crystals were pointing come the magnetic north pole, the place of the pole seemed to wander. Researchers were amazed to find that the north magnetic pole adjusted location v time (figure 6).

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To check this, historicsweetsballroom.comlogists fitted the continents together as Wegener had actually done. The worked! There has actually only to be one magnetic phibìc pole and the continents have actually drifted (figure 7). They called the phenomenon the the magnetic pole that appeared to move but actually did no apparent polar wander.