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In the early 19th century the mining industry and Industrial Revolution stimulated the rapid development of the stratigraphic column - “the sequence of rock formations arranged according to their order of formation in time.”[16] In England. the mining surveyor William Smith, starting in the 1790s, found empirically that fossils were a highly effective means of distinguishing between otherwise similar formations of the landscape as he travelled the country working on the canal system and produced the first geological map of Britain. At about the same time, the French comparative anatomist Georges Cuvier assisted by his colleague Alexandre Brogniart at the École des Mines de Paris realized that the relative ages of fossils could be determined from a geological standpoint; in terms of what layer of rock the fossils are located and the distance these layers of rock are from the surface of the Earth. Through the synthesis of their findings, Brogniart and Cuvier realized that different strata could be identified by fossil contents and thus each stratum could be assigned to a unique position in a sequence.[17] After the publication of Cuvier and Brongniart’s book, “Description Geologiques des Environs de Paris” in 1811, which outlined the concept, stratigraphy became very popular amongst geologists; many hoped to apply this concept to all the rocks of the Earth.[18] During this century various geologists further refined and completed the stratigraphic column. For instance, in 1833 while Adam Sedgwick was mapping rocks that he had established were from the Cambrian Period, Charles Lyell was elsewhere suggesting a subdivision of the Tertiary Period;[19] whilst Roderick Murchison, mapping into Wales from a different direction, was assigning the upper parts of Sedgewick's Cambrian to the lower parts of his own Silurian Period.[20] The stratigraphic column was significant because it supplied a method to assign a relative age of these rocks by slotting them into different positions in their stratigraphical sequence. This created a global approach to dating the age of the Earth and allowed for further correlations to be drawn from similarities found in the makeup of the Earth’s crust in various countries. Geological map of Great Britain by William Smith, published 1815. In early nineteenth-century Britain, catastrophism was adapted with the aim of reconciling geological science with religious traditions of the biblical Great Flood. In the early 1820s English geologists including William Buckland and Adam Sedgwick interpreted "diluvial" deposits as the outcome of Noah's flood, but by the end of the decade they revised their opinions in favour of local inundations.[21] Charles Lyell challenged catastrophism with the publication in 1830 of the first volume of his book Principles of Geology which presented a variety of geological evidence from England, France, Italy and Spain to prove Hutton’s ideas of gradualism correct.[17] He argued that most geological change had been very gradual in human history. Lyell provided evidence for Uniformitarianism; a geological doctrine that processes occur at the same rates in the present as they did in the past and account for all of the Earth’s geological features.[22] Lyell’s works were popular and widely read, the concept of Uniformitarianism had taken a strong hold in geological society.[17] During the same time that the stratigraphic column was being completed, imperialism drove several countries in the early to mid 19th century to explore distant lands to expand their empires. This gave naturalists the opportunity to collect data on these voyages. In 1831 Captain Robert FitzRoy, given charge of the coastal survey expedition of HMS Beagle, sought a suitable naturalist to examine the land and give geological advice. This fell to Charles Darwin, who had just completed his BA degree and had accompanied Sedgwick on a two week Welsh mapping expedition after taking his Spring course on geology. Fitzroy gave Darwin Lyell’s Principles of Geology, and Darwin became Lyell's first disciple, inventively theorising on uniformitarian principles about the geological processes he saw, and challenging some of Lyell's ideas. He speculated about the Earth expanding to explain uplift, then on the basis of the idea that ocean areas sank as land was uplifted, theorised that coral atolls grew from fringing coral reefs round sinking volcanic islands. This idea was confirmed when the Beagle surveyed the Cocos (Keeling) Islands. Darwin's discovery of giant fossils helped to establish his reputation as a geologist, and his theorising about the causes of their extinction led to his theory of evolution by natural selection published in On the Origin of Species in 1859.[21][23][24] Economic motivations for the practical use of geological data caused governments to support geological research. During the 19th century the governments of several countries including Canada, Australia, Great Britain and the United States funded geological surveying that would produce geological maps of vast areas of the countries. Geological surveying provides the location of useful minerals and such information could be used to benefit the country’s mining industry. With the government funding of geological research, more individuals could study geology with better technology and techniques, leading to the expansion of the field of geology.[8] In the 19th century, scientific realms established the age of the Earth in terms of millions of years. By the early 20th century the Earth’s estimated age was 2 billion years. Radiometric dating determined the age of minerals and rocks, which provided necessary data to help determine the Earth’s age.[25] With this new discovery based on verifiable scientific data and the possible age of the Earth extending billions of years, the dates of the geological time scale could now be refined. Theories that did not comply with the scientific evidence that established the age of the Earth could no longer be accepted. |
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