![]() New Games - Play free with absolutely no time limit! The Age of Discovery or the Age of Exploration from the end of the 15th century to the 18th century, was an informal and loosely defined European historical period. Ice age - Wikipedia. An ice age is a period of long- term reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Within a long- term ice age, individual pulses of cold climate are termed "glacial periods" (or alternatively "glacials" or "glaciations" or colloquially as "ice age"), and intermittent warm periods are called "interglacials". In the terminology of glaciology, ice age implies the presence of extensive ice sheets in both northern and southern hemispheres.[1] By this definition, we are in an interglacial period—the Holocene—of the ice age. The ice age began 2. Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice sheets still exist.[2]Origin of ice age theory. In 1. 74. 2 Pierre Martel (1. Geneva, visited the valley of Chamonix in the Alps of Savoy.[3][4] Two years later he published an account of his journey. FLING.COM - World's Best Adult Personals for adult dating, search millions of adult personals from singles, couples, and swingers looking for fun, browse sexy photos. Download cheat engine 6.2 free, Cheat Engine is a free piece of software and the hacking process is quite simple. Cheat engine is used to hack Health, Skill. He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, saying that they had once extended much farther.[5][6] Later similar explanations were reported from other regions of the Alps. In 1. 81. 5 the carpenter and chamois hunter Jean- Pierre Perraudin (1. Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further.[7] An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss- German geologist Jean de Charpentier (1. Comparable explanations are also known from the Val de Ferret in the Valais and the Seeland in western Switzerland[9] and in Goethe's scientific work.[1. Such explanations could also be found in other parts of the world. When the Bavarian naturalist Ernst von Bibra (1. Chilean Andes in 1. Meanwhile, European scholars had begun to wonder what had caused the dispersal of erratic material. From the middle of the 1. The Swedish mining expert Daniel Tilas (1. Scandinavian and Baltic regions.[1. In 1. 79. 5, the Scottish philosopher and gentleman naturalist, James Hutton (1. Alps by the action of glaciers.[1. Two decades later, in 1. Swedish botanist Göran Wahlenberg (1. Scandinavian peninsula. He regarded glaciation as a regional phenomenon.[1. Only a few years later, the Danish- Norwegian geologist Jens Esmark (1. In a paper published in 1. Esmark proposed changes in climate as the cause of those glaciations. He attempted to show that they originated from changes in Earth's orbit.[1. During the following years, Esmark's ideas were discussed and taken over in parts by Swedish, Scottish and German scientists. At the University of Edinburgh Robert Jameson (1. Esmark's ideas, as reviewed by Norwegian professor of glaciology Bjørn G. Andersen (1. 99. 2).[1. Jameson's remarks about ancient glaciers in Scotland were most probably prompted by Esmark.[1. In Germany, Albrecht Reinhard Bernhardi (1. Dreissigacker, since incorporated in the southern Thuringian city of Meiningen, adopted Esmark's theory. In a paper published in 1. Bernhardi speculated about former polar ice caps reaching as far as the temperate zones of the globe.[1. In 1. 82. 9, independently of these debates, the Swiss civil engineer Ignaz Venetz (1. Alps, the nearby Jura Mountains, and the North German Plain as being due to huge glaciers. When he read his paper before the Schweizerische Naturforschende Gesellschaft, most scientists remained sceptical.[1. Finally, Venetz convinced his friend Jean de Charpentier. De Charpentier transformed Venetz's idea into a theory with a glaciation limited to the Alps. His thoughts resembled Wahlenberg's theory. In fact, both men shared the same volcanistic, or in de Charpentier's case rather plutonistic assumptions, about the Earth's history. In 1. 83. 4, de Charpentier presented his paper before the Schweizerische Naturforschende Gesellschaft.[2. In the meantime, the German botanist Karl Friedrich Schimper (1. Bavaria. He began to wonder where such masses of stone had come from. During the summer of 1. Bavarian Alps. Schimper came to the conclusion that ice must have been the means of transport for the boulders in the alpine upland. In the winter of 1. Munich. Schimper then assumed that there must have been global times of obliteration ("Verödungszeiten") with a cold climate and frozen water.[2. Schimper spent the summer months of 1. Devens, near Bex, in the Swiss Alps with his former university friend Louis Agassiz (1. Jean de Charpentier. Schimper, de Charpentier and possibly Venetz convinced Agassiz that there had been a time of glaciation. During the winter of 1. Agassiz and Schimper developed the theory of a sequence of glaciations. They mainly drew upon the preceding works of Venetz, de Charpentier and on their own fieldwork. Agassiz appears to have been already familiar with Bernhardi's paper at that time.[2. At the beginning of 1. Schimper coined the term "ice age" ("Eiszeit") for the period of the glaciers.[2. In July 1. 83. 7 Agassiz presented their synthesis before the annual meeting of the Schweizerische Naturforschende Gesellschaft at Neuchâtel. The audience was very critical and some opposed to the new theory because it contradicted the established opinions on climatic history. Most contemporary scientists thought that the Earth had been gradually cooling down since its birth as a molten globe.[2. In order to overcome this rejection, Agassiz embarked on geological fieldwork. He published his book Study on Glaciers ("Études sur les glaciers") in 1. De Charpentier was put out by this, as he had also been preparing a book about the glaciation of the Alps. De Charpentier felt that Agassiz should have given him precedence as it was he who had introduced Agassiz to in- depth glacial research.[2. Besides that, Agassiz had, as a result of personal quarrels, omitted any mention of Schimper in his book.[2. All together, it took several decades until the ice age theory was fully accepted by scientists. This happened on an international scale in the second half of the 1. James Croll, including the publication of Climate and Time, in Their Geological Relations in 1. Evidence for ice ages. There are three main types of evidence for ice ages: geological, chemical, and paleontological. Geological evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret. Furthermore, this evidence was difficult to date exactly; early theories assumed that the glacials were short compared to the long interglacials. The advent of sediment and ice cores revealed the true situation: glacials are long, interglacials short. It took some time for the current theory to be worked out. The chemical evidence mainly consists of variations in the ratios of isotopes in fossils present in sediments and sedimentary rocks and ocean sediment cores. For the most recent glacial periods ice cores provide climate proxies from their ice, and atmospheric samples from included bubbles of air. Because water containing heavier isotopes has a higher heat of evaporation, its proportion decreases with colder conditions.[2. This allows a temperature record to be constructed. However, this evidence can be confounded by other factors recorded by isotope ratios. The paleontological evidence consists of changes in the geographical distribution of fossils. During a glacial period cold- adapted organisms spread into lower latitudes, and organisms that prefer warmer conditions become extinct or are squeezed into lower latitudes. This evidence is also difficult to interpret because it requires (1) sequences of sediments covering a long period of time, over a wide range of latitudes and which are easily correlated; (2) ancient organisms which survive for several million years without change and whose temperature preferences are easily diagnosed; and (3) the finding of the relevant fossils. Despite the difficulties, analysis of ice core and ocean sediment cores[3. These also confirm the linkage between ice ages and continental crust phenomena such as glacial moraines, drumlins, and glacial erratics. Hence the continental crust phenomena are accepted as good evidence of earlier ice ages when they are found in layers created much earlier than the time range for which ice cores and ocean sediment cores are available. Major ice ages. Timeline of glaciations, shown in blue.
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