Ancient fossils of the same species of extinct plants and animals are found in rocks of the same age but are on continents that are now widely separated figure 3. Wegener proposed that the organisms had lived side by side, but that the lands had moved apart after they were dead and fossilized. He suggested that the organisms would not have been able to travel across the oceans. Fossils of the seed fern Glossopteris were too heavy to be carried so far by wind.
Mesosaurus was a swimming reptile but could only swim in fresh water. Cynognathus and Lystrosaurus were land reptiles and were unable to swim Figure 3. Grooves and rock deposits left by ancient glaciers are found today on different continents very close to the equator. Today glaciers only form on land and nearer the poles. Wegener thought that the glaciers were centered over the southern land mass close to the South Pole and the continents moved to their present positions later on.
Coral reefs and coal-forming swamps are found in tropical and subtropical environments, but ancient coal seams and coral reefs are found in locations where it is much too cold today. Wegener suggested that these creatures were alive in warm climate zones and that the fossils and coal later had drifted to new locations on the continents.
Magnetic Polarity on the Same Continent with Rocks of Different Ages Geologists noted important things about the magnetic polarity of different aged rocks on the same continent: Magnetite crystals in fresh volcanic rocks point to the current magnetic north pole figure 5 no matter what continent or where on the continent the rocks are located.
Older rocks that are the same age and are located on the same continent point to the same location, but that location is not the current north magnetic pole. Older rock that are of different ages do not point to the same locations or to the current magnetic north pole. There are three possible explanations for this: The continents remained fixed and the north magnetic pole moved.
The north magnetic pole stood still and the continents moved. Both the continents and the north pole moved. And for geologists he was an outsider who dared to question the foundations of their science, so most of them rejected his ideas with the backing of figures like Einstein, who wrote the prologue to a book that ridiculed Wegener. It is also true that he made some blunders, calculating that Greenland was approaching North America at a rate of 1.
That was like saying that a plough can move on its own and leave no furrows. Tests were done, but with the most reliable instruments of the time no movement of the continents was detected.
The edition of the Encyclopedia Britannica still did not believe Wegener, but that year many geologists began siding with him, in view of new evidence. This new theory— plate tectonics —also explained that earthquakes and tsunamis occur when two plates rub against one another, and that when they collide head-on, large mountain ranges are formed.
In addition, thanks to geolocation satellites, we are now able to detect that Europe and North America are moving apart, although at the same speed that a fingernail grows: two metres in a lifetime.
Today we have all learned at school—or even before, in cartoons—the theory of continental drift. But Wegener died in , long before his success was recognised. During an expedition in Greenland, he left the camp for supplies and was found frozen months later. He was buried there and is still there, although he is now about two metres further away from his birthplace in Berlin.
Click Enter. Reaching as tall as 30 meters, the Glossopteris emerged during the early Permian period million years ago and became the dominant land plant species until the end of the Permian. Now, the Glossopteris seed is known to be large and bulky and therefore could not have drifted or flown across the oceans to a separate continent. Description showing the fossil locations of the Mesosaurus, Cynognathus, Lystrosaurus, and Glossopteris spread across different continents.
If the continents of the Southern Hemisphere are put together, the distribution of these four fossil types form continuous patterns across continental boundaries. Of course, possible explanations are brought to attention. One explanation is the species could have migrated via a land bridge or swam to the other continents. However, a land bridge is not applicable due to the differences in densities between the continents and oceans floor and violation of the isostasy concept.
Moreover, swimming as a possibility is foolish due to the lack of formidable swimming capabilities to travel across such an extensive body of water like the Atlantic. Scientists argued that there was no way to explain how solid continents could plow through solid oceanic crust.
Skip to main content. Plate Tectonics. Search for:. Theory of Continental Drift The continental drift hypothesis was developed in the early part of the 20th century, mostly by Alfred Wegener. Scientists used magnetometers, devices capable of measuring the magnetic field intensity, to look at the magnetic properties of rocks in many locations. Geologists noted important things about the magnetic polarity of different aged rocks on the same continent.
Magnetite crystals in fresh volcanic rocks point to the current magnetic north pole no matter what continent or where on the continent the rocks are located. Older rocks that are the same age and are located on the same continent point to the same location, but that location is not the current north magnetic pole. Older rock that are of different ages do not point to the same locations or to the current magnetic north pole.
In other words, although the magnetite crystals were pointing to the magnetic north pole, the location of the pole seemed to wander. Scientists were amazed to find that the north magnetic pole changed location through time.
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