Geology And Geophysics

Alfred Wagner and Harry Hess Plate Tecton



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Plate tectonics: More than a theory

The Earth is in a state of change. It has been in this state since its beginning, some 4.5 billion years ago. It will continue to change long into the future. Try as we might, there is no escaping it. In limited detail, this article will explore one of the many ways this planet undergoes change. Albeit a slow one, here we will examine the scientific history of the amazing process that is plate tectonics.

To begin, near the turn of the 20th century, a meteorologist named Alfred Wagner was one of the first to begin to grasp the idea of plate movement. He was truly ahead of his time. Wagner theorized, through a comparison of Paleozoic fossils and rocks, the continents we see today were once joined together in a single supercontinent called Pangaea.

Now, when most folks think of Pangaea, they often envision a world much unlike our own. And, in many ways, they are correct. It was different. Very different. If you could imagine Europe, Asia, Africa, India, North America, Antarctica, South America, and Australia all slapped together in one, single super mass you are on the right track. Take another step, and you will witness a time and place inhabited by creatures many of us would jump at the chance just to get a look at.

Yes, the remarkable and fantastic supercontinent of Pangaea was like something straight from a science fiction novel.

P-a-n-g-a-e-a.

Even the name has a wild ring to it.

Still, alas, nothing lasts forever. Yet, again, the Earth did change; and the process Alfred Wagner used to explain this change was continental drift:

"Continental drift is the idea that continents move freely over Earth's surface, changing their positions relative to one another" (468).

When we examine a present-day map of the world, it is fairly easy to see how the continents fit together 225 million years ago. It doesn't take a trained geologic eye to unravel the puzzle.

Unfortunately, and despite the obvious, even the best of theories do often suffer the worst of skepticism, and Wagner's theory was no exception. It's how the scientific method works. Hence, from a present-day perspective - and with a greater understanding of geologic processes - we can now see how the idea of continental drift does have its problems.

For one, Wagner made the mistake of believing the sea floor was stationary. We now know it isn't. We can hardly blame the man for his short-sightedness. We owe him a great amount of debt, and not to mention gratitude, for being far ahead of his time.

Second, Wagner was not so adept at explaining why or, more specifically, how it happened. So, in all, when we put two and two together, it is not too surprising his ideas were soon buried by the scientific community and would not resurface until much later.

At the time, did they all think Wagner was a bit of a quack?

Most likely.

Nevertheless, science did continue on, and, 60 years after Wagner, a geologist by the name of Harry Hess revamped Wagner's old idea. Hess, in his astute, geologic brilliancy, moved the field of geology another leap forward with his theory of sea floor spreading:

"Sea floor spreading is a hypothesis that the sea floor forms at the crest of the mid-oceanic ridge, then moves horizontally away from the ridge crest toward an oceanic trench. The two sides of the ridge are moving in opposite directions like slow conveyor belts" (468).

Thus, through a combination of both Wagner's and Hess's theories, we have finally arrived at the unified theory of plate tectonics. Amazing, don't you think? I am not going to offer you a long discourse on how it all works exactly. (If you are curious, please feel free to look it up yourself.) Just know, for now, plate tectonics is responsible for earthquakes, volcanic activity, mountain ranges, and even island chains. In more ways than one, the movement of both oceanic and continental plates has given birth to the shape of the planet, and, as an added bonus, it has withstood the tests of all scientific scrutiny. Yes, it was around long before a great ape fueled a fire, fashioned a tool, and uttered a prayer. Yes, plate tectonics was around long before one of us looked up and contemplated the stars; and, for whatever it is worth, chose to build a pyramid, a skyscraper, or a cathedral.

And there is little doubt it will be around long after.

Works Cited Plummer, Charles C., McGeary, David., and Carlson, Diane H. Physical Geology (Tenth Edition. New York: McGraw-Hill, 2005.

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