Continental Drift

Abstract

Continental drift can be shown to be true by the scientific theory presented by various scientists throughout history. The scientific method and theory development can be used to prove the hypothesis of continental drift, seafloor spreading, and plate tectonics. Plate tectonics are shown as a viable explanation for the various and varied geological formations and features found throughout the world.

Continental Drift

When you look at a map, you will notice that some of the continents look as if they fit together like a puzzle. When the first accurate maps were made, many people made the same observation and wondered why this was. Early in the twentieth century, a German scientist named Alfred Wegener suggested that the continents had once been joined together as a single landmass he called Pangaea (meaning all-Earth). He said that Pangaea broke apart forming the present continents. Over tens of millions of years the continents slowly moved or drifted to their present positions. This theory has become known as continental drift.

This idea was so different that few geologists took it seriously. But Wegener supported his theory with several pieces of evidence one of which was he used landforms. Wegener showed that the shoreline of South America would fit remarkably well with the shoreline of Africa if the Atlantic Ocean were closed up. He showed that a mountain range in South Africa lines up with a mountain range in Argentina. In addition, Brazilian coal fields match up with identical coal fields in Africa. Second, he pointed to a fossil of a fernlike plant that has been found in Africa, South America, Australia, India, and Antarctica. Third, Wegener noted evidence that certain continents had once been exposed to different climates. For example, deep scratches in rocks showed that glaciers once covered South Africa. The climate of South Africa today is far too mild for glaciers to form. Rather than suggesting that the climate had changed, Wegener proposed that South Africa had once been much closer to the South Pole.

Although a few geologists accepted Wegener's theory, most scientists found it to absurd to think about continents plowing through solid rock on the ocean floor. Further evidence had to come from the ocean floor itself. Extended exploration of the ocean depths, made possible by technological advances achieved during World War II, revealed a great system of underwater mountains that encircle Earth like the seams on a baseball. This underwater mountain range is known as the system of mid-ocean ridges.

In 1960, an American geologist named Harry Hess reconsidered Wegener's theory in light of his research into the mid-ocean ridge. He suggested that molten material from the mantle rises and erupts though a valley that runs along the center of the mid-ocean ridge. The molten material then spreads out, pushing older rock to both sides. As the molten material cools, it forms strips of solid rock in the center of the ridge. Over time, more molten material erupts. This material splits apart the strip of solid rock that formed before, pushing it to either side. Hess called this process sea-floor spreading.

Several other forms of evidence supported Hess's theory of sea-floor spreading. First,, scientist found evidence that new material is indeed erupting along the mid-ocean ridge. Scientists found strange rocks shaped pillows, which can form only when molten material hardens quickly after erupting underwater.

As we all know the earth is magnetic and acts like a huge magnet. The rock on the ocean floor contains iron, which is a magnetic material. When the rock is still soft, the iron bits line up in the direction of the Earth's magnetic field. As the rock hardens, the iron bits are locked into place like a magnetic memory. The direction of the magnetism depends on the location of Earth's magnetic poles. Earth's magnetic poles have reversed themselves several times, every 300,000 years of so. In other words, the north magnetic pole became the south magnetic pole and the south magnetic pole became the north magnetic pole. If the entire ocean floor was formed at the same time, all of the rock should be magnetized in the same direction. But this is not the case. Instead scientists found stripes. The magnetic material in one stripe of rock points in one direction,, while a parallel stripe points in the other direction. These stripes indicated that the rocks could not have been formed at the same time.

Further evidence comes from rock samples taken from the ocean floor. When the age of the samples were determined, they it was found that the further away from the ridge, on either side, the rocks became older. The youngest rocks are always found near the center of the ridges.

The process of scientific method is when you ask a question about something that you observe: How, What, When, Who, Which, Why, or Where? But in order for the scientific method to actually answer the question it must be about something that you can measure, preferably with a number or statistics. Next rather than starting from scratch in putting together everything yourself and when answering your question, you are allowed to cheat a bit by using the library or Internet research to help you find out how to do things, by looking at how others did them, thereby making sure that you don't make the same mistakes again. Then you are going to want to make a hypothesis , which is just an educated guess about how things work i.e.

"If _____[I do this] _____, then _____[this]_____ will happen." Your hypothesis must be made in a way that can easily be measured, and of course, your hypothesis should help you answer your original question.

Next you want to experiment and conduct tests to see whether your hypothesis is true or false. Your experiment must be a fair test. You can conduct a fair test by making sure that you change only one variable at a time while keeping all other factors the same. You want to also repeat your experiments several times to make sure that the first results weren't just a fluke.

Once you are finished with you experiment, you will