Meteorite Impacts


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THE THIRD PLANET E. R. Swanson – spring 2009 METEORITE IMPACTS Introduction A meteoroid traveling through space becomes a meteor when it blazes through the Earth’s atmosphere and it is known as a meteorite after it impacts the ground . Meteors are objects that have left the realm of astronomy to become a part of the Earth and geology. Large meteors, sometimes called asteroids, can even become geological agents of erosion and more. Asteroids and comets can significantly impact (puns still always intended) life on Earth. They have profoundly affected geologic history, and they hold the potential for profoundly ending human history. Speaking of ending, this meeting of space and Earth seems an appropriate way to end the course. In doing so we have come full circle back to the astronomy, the point from where we began. In the astronomy section we discovered how the 3rd planet from the Sun fits into the grand (really grand) scheme of things. We recognized that Earth is just one among trillions of trillions of other places, and we tried to imagine the unimaginable size of the universe. We will end the course as life on Earth may end with one of those trillions of places chaotically causing our demise. Early in the text we traced the development of Astronomy from the Ancient Greeks to Sir Isaac Newton and the Age of Enlightenment. We learned how science began to view the Universe as an orderly place governed by universal laws. Biologists starting seeing order in plants and animals and arranging them in orderly groups with cultured Latin names that confound students yet today (e.g. Armadillidium vulgare was used instead of simply using pill bug or roly poly for the critter that everyone on the planet can plainly see looks like a vulgar little armadillo – Oh, I think that I am beginning to get it). In section two of the course we saw how geologists picked up this “order in nature theme” with the Principle of Uniformitarianism. No longer was it necessary to call upon catastrophes like great floods and upheavals to explain the landforms around us or to understand what was being revealed about earth history through the study of rocks. Earth history, it seemed, could all be explained by the ordinary forces of nature that we see operating every day, given a sufficiently long period of time. Modern Geology, however, is writing catastrophes back into geologic history. It is not that Uniformitarianism was so terribly wrong; it is just that that those Enlightenment Age geologists were still thinking small. When they though about present day processes of nature, they were still viewing “day” in human terms. They needed to expand their view of what constitutes present day so that all geologic processes are included. A day, a week or a century is not enough time to experience a representative sampling of the incredible range in geologic processes. The tides may carry sediment in and out twice a day and a Vesuvius may bury a Pompeii once in recorded history, but a typical week or millennium
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This note was uploaded on 09/09/2009 for the course GEO 301 taught by Professor Long during the Spring '07 term at University of Texas.

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