Why do we suffer through volcanoes, earthquakes, and other terrors of such? Why are the same types of dinosaur fossils found in Europe and Antarctica? Why do the continents fit together like a jigsaw puzzle? Was there really a continent called Pangea; if so, where did it go? Why are the Himalayas so great in size?
Plate Tectonics answers all of these questions and many more.
Plate Tectonics is the theory that describes plate movements in the past, the present, and what will soon be today, the future. It shows where continents were yesterday and where they will possibly be tomorrow.
The ancient people of our world did not know why these things occurred, so they made up many reasons. They mainly linked the events of the natural world to the work of gods. For example, the Japanese thought that earthquakes were the work of the Namazu, or giant catfish. The Romans, on the other hand, said that volcanoes were caused by Vulcan, the crippled blacksmith god, working at his forge. The Hawaiian Islanders thought that eruptions were the work of Pele, fire god.
Greek Philosopher Aristotle (384-322 B.C.), said that the Earth was made up of huge caverns with tunnels that wind flowed through, causing pressure to build up and the Earth to shake.
Starting in the 1600's, people began to question of what the Earth was actually made up. In that time period, English Philosopher Francis Bacon, noted that the coast of South America and Africa fit together like a jig-saw puzzle. He noted that this was "no mere accidental occurrence". The people at this time were biblically guided and explained this occurrence, by saying that the excess water from Noah's flood, or the Great Deluge, caused the resemblance.
>James Ussher, of Ireland, said that Creation started the night of October 22, 4004 B.C. at about the same time as Francis Bacon was making his discoveries. He came to this conclusion by adding up the life spans of people in the Old Testament of the Bible (on a side note: he had a wholelot of free time).
James Hutton, of Scotland, questioned Ussher's theory on the date of Creation. He could see that 6000 years would have been too short of a time period for land forms to form and then evolve into what is now their present state. His solution was quite simple - "geologic time", or the time it takes for land forms to form and erode.
Alexander von Humbolt was another one of those people who saw the beginnings of plate tectonics but really didn't act on what he saw. This German noticed that rock layers were the same in the east of South America and in Africa. He realized that this could not be a mere coincidence.
Even as late as the 18th century, people couldn't agree about what caused the events of the Earth. The two prevailing theories of that time were each based on completely different ideas. The first of these two was the Neptunist Idea. This stated that the Earth was made up of a solid core which was surrounded by watery materials. These materials settled, slowly becoming the rocks on the Earth's surface. This theory conveniently described where all the water on the Earth had come from. The other theory of this time, the Platonist Idea, said that the Earth had a hot interior of molten rock which erupted onto the surface.
In the Mid-1800's, a scientist by the name of James Dwight Dana had the theory that the Earth was made up of a hot molten center, and that it was slowly cooling, thus, causing the Earth to shrink and contract. This in turn formed the mountains and ocean basins. His only thoughts on Earthquakes were that when they occurred, zones of rock were fractured. He had NO opinions of what caused the earthquakes (it was a small necessity, really). These same fractures were the holes from which lava spewed in volcanoes.
Sir George Airy had another brilliant theory about the continents and mountains. He thought that mountains and continents moved like icebergs, floating on top of a sea of magma. The reason that the mountains floated higher, according to him, was that they were made up of a lighter material, granite, than the continent's basalt.
By the 1870's, a majority of geologists agreed that the Earth probably had a solid center core surrounded by a liquid mantle. This mantle was then surrounded by a solid crust. Until 1880, there was no proof supporting this theory. At that time, an English engineer by the name of John Milene created the seismograph. The seismograph told the scientists what they thought all along, that the Earth was made up of a solid core and that it was surrounded by a mantle which was then surrounded by a crust.
Frank Taylor also had a one-of-a-kind theory. This one was closer to the truth, but still a fair shot off. This theory stated that the continents were originally two large land masses floating over the North and South poles. South America, Africa, and Australia had their origins in the southern land mass (the one over the South Pole), and the northern land mass had broken apart, forming Europe, Asia, and North America. These continents were slowly moving toward the Equator, caused by the Moon's gravitational pull.
All of these early theories had a great impact on the current state of the theory of plate tectonics, some more than others. There were strokes of brilliance in them all, yet the theory of plate tectonics has undergone some major changes. More can be found out about plate tectonic's present state here.