Information AboutUniformitarianism (science) |
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Uniformitarianism, though often treated as a single idea, is in fact a family of four related (but not identical) propositions. Paleontologist and evolutionary theorist onward. The second and particularly the third senses remained controversial and (though more increasingly accepted in the 20th Century ) have been occasionally challenged by scientists who believe the ''presumption'' of uniformity (in the second and third senses) is unwarranted. UNIFORMITARIANISM AND THE HISTORY OF GEOLOGY Uniformitarianism is one of the most basic principles of modern Geology , the observation that fundamentally the same geological processes that operate today also operated in the distant past. It exists in contrast with Catastrophism , which states that Earth surface features originated suddenly in the past, by radically different geological processes than those currently occurring. Note, however, that many "catastrophic" events are perfectly compatible with uniformitarianism. For example, Charles Lyell thought that ordinary geological processes would cause Niagara Falls to move upstream to Lake Erie within 10000 years, leading to catastrophic flooding of a large part of North America. Uniformitarianism is a generalisation of the principle of Actualism , which states that present day-processes (astronomical, geological, Paleontological ,...) can be used to interpret past patterns. It is also known as "the present is the key to the past". The principle of actualism is the cornerstone of Paleoecology . The geologist James Hutton was a pioneer of the principle, which was later popularised by Charles Lyell and influenced Charles Darwin . In the 18th and 19th centuries, the debate between the two theories was intense, since uniformitarianism seemed hard to reconcile with the prevailing Religious Beliefs of the time. Today, however, all mainstream scientists support uniformitarianism as do most mainstream religious denominations. The understanding of slow geological processes have changed in several ways. Before Continental Drift (see Plate Tectonics ) was recognized in the 20th Century , the surface of Earth was believed to have remained generally unchanged since creation. Cooling from a molten state was believed to have caused shrinkage, which caused mountains and folding of the surface. Currently it is accepted that much of the Mantle is plastic and fluid, and the Crust is slowly moving over it. It is this relative motion that produces folding, compression, rises, depressions, etc. In recent decades, the theory of uniformitarianism has been modified to reflect the discovery that catastrophic events occur today and have occurred in the Earth's past. The present is still the key to the past, Meteorite impacts, giant Earthquake s, Tsunami s, and explosive Volcanism occur today as they have in the past and these events provide ''punctuations'' in an over-all gradual process. |
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