Finally, Venetz convinced his friend Jean de Charpentier.
When he read his paper before the Swiss Society for Natural Research, most scientists remained sceptical. In 1829, independently of these debates, the Swiss civil engineer Ignaz Venetz (1788–1859) explained the dispersal of erratic boulders in the Alps, the nearby Jura Mountains, and the North German Plain as being due to huge glaciers. In a paper published in 1832, Bernhardi speculated about the polar ice caps once reaching as far as the temperate zones of the globe. In Germany, Albrecht Reinhard Bernhardi (1797–1849), a geologist and professor of forestry at an academy in Dreissigacker (since incorporated in the southern Thuringian city of Meiningen), adopted Esmark's theory. Jameson's remarks about ancient glaciers in Scotland were most probably prompted by Esmark. At the University of Edinburgh Robert Jameson (1774–1854) seemed to be relatively open to Esmark's ideas, as reviewed by Norwegian professor of glaciology Bjørn G. ĭuring the following years, Esmark's ideas were discussed and taken over in parts by Swedish, Scottish and German scientists. Esmark's discovery were later attributed to or appropriated by Theodor Kjerulf and Louis Agassiz. Esmark discovered the similarity between moraines near Haukalivatnet lake near sea level in Rogaland and moraines at branches of Jostedalsbreen. He attempted to show that they originated from changes in Earth's orbit. In a paper published in 1824, Esmark proposed changes in climate as the cause of those glaciations. Only a few years later, the Danish-Norwegian geologist Jens Esmark (1762–1839) argued for a sequence of worldwide ice ages. Haukalivatnet lake (50 meters above sea level) where Jens Esmark in 1823 discovered similarities to moraines near existing glaciers in the high mountains. He regarded glaciation as a regional phenomenon. Two decades later, in 1818, the Swedish botanist Göran Wahlenberg (1780–1851) published his theory of a glaciation of the Scandinavian peninsula. In 1795, the Scottish philosopher and gentleman naturalist, James Hutton (1726–1797), explained erratic boulders in the Alps by the action of glaciers. The Swedish mining expert Daniel Tilas (1712–1772) was, in 1742, the first person to suggest drifting sea ice was a cause of the presence of erratic boulders in the Scandinavian and Baltic regions. From the middle of the 18th century, some discussed ice as a means of transport. Meanwhile, European scholars had begun to wonder what had caused the dispersal of erratic material. When the Bavarian naturalist Ernst von Bibra (1806–1878) visited the Chilean Andes in 1849–1850, the natives attributed fossil moraines to the former action of glaciers. Such explanations could also be found in other parts of the world. Comparable explanations are also known from the Val de Ferret in the Valais and the Seeland in western Switzerland and in Goethe's scientific work. An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss-German geologist Jean de Charpentier (1786–1855) in 1834. In 1815 the carpenter and chamois hunter Jean-Pierre Perraudin (1767–1858) explained erratic boulders in the Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further. Later similar explanations were reported from other regions of the Alps. 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. Two years later he published an account of his journey. In 1742, Pierre Martel (1706–1767), an engineer and geographer living in Geneva, visited the valley of Chamonix in the Alps of Savoy. See also: History of climate change science The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for the next 500,000 years, which otherwise would begin in around 50,000 years, and likely more glacial cycles after. By this definition, Earth is currently in an interglacial period-the Holocene.
In glaciology, ice age implies the presence of extensive ice sheets in both northern and southern hemispheres. Individual pulses of cold climate within an ice age are termed glacial periods (or, alternatively, glacials, glaciations, glacial stages, stadials, stades, or colloquially, ice ages), and intermittent warm periods within an ice age are called interglacials or interstadials. Earth is currently in the Quaternary glaciation. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. An artist's impression of ice age Earth at glacial maximum.Īn ice age is a long period of 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.
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