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History and physical geography of the Arctic


The Arctic, the northmost region of the planet, is centered on the pole and characterized by distinctively polar conditions of climate, plant and animal life, and alternative physical options. The term comes from the Greek arktos (“bear”), about the northern constellation of the Bear. It's typically been wont to designate the realm at intervals the polar circle a mathematical line that's drawn at latitude 66°30′ N, marking the southern limit of the zone that there's a minimum of one annual amount of twenty-four hours throughout which the sun doesn't set and one throughout which it doesn't rise. This line, however, is while not worth a geographic boundary, since it's not keyed to the character of the terrain.

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Arctic Ocean

While no differentiation is definitive, a generally useful guide is that the irregular line marking the north limit of the stands of trees. The regions north of the line embrace Gronland (Kalaallit Nunaat), Svalbard, and different polar islands; the northern parts of the mainlands of geographical region, Alaska, and Canada; the coasts of Labrador; the north of Iceland; and a strip of the Arctic coast of Europe. The last-named area, however, is assessed as a line of latitude as a result of various factors.

permanent snow and ice within of the high country and grasses, sedges, and low shrubs within the lowlands; and for well-frozen ground (permafrost), the surface layer of that is subject to summer thawing. Three-fifths of the Arctic piece of land is outside the zones of permanent ice. The brevity of the Arctic summer is partially remunerated by the long daily period of the summer sunshine.

since war 2 International interest within of the Arctic and polar circle, regions has steadily redoubled throughout of the twentieth century, significantly. 3 major factors square measure involved: the benefits of the North Pole route as a crosscut between vital centers of population, the growing realization of economic potentialities like mineral (especially petroleum) and forest resources and grazing areas, and therefore the importance of the regions within the study of worldwide meteorology.

Physical geography

The land


The Arctic lands have developed geologically around 4 nuclei of the ancient crystalline rocks. The biggest of those, the Canadian protect, underlies all the Canadian Arctic apart from a part of the Queen Elizabeth Islands. It's separated by sea from an identical protected space that underlies most of the island. The Baltic or Scandinavian protect, centered on Suomi, includes all of northern Scandinavia except the Norwegian coast and also the northwestern corner of Russia. The 2 different blocks square measure smaller.

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In the sectors between the shields, there are long periods of marine alluviation, and consequently, the shields area unit is partially buried. In some areas thick sediments were afterward pleated, therefore manufacturing mountains, several of that have since been destroyed by erosion. 2 main orogenies (mountain-building periods) are recognized within the Arctic. In Paleozoic era times (about 542 million to 251 million years ago) there developed a posh mountain system that has each Caledonian and Hercynian components. It extends from the Queen Elizabeth Islands through Robert Peary Land and on the geographical region of the island. Mountain building occurred throughout an equivalent amount in Svalbard, Nova Zembla, the northern chain, the Taimyr Peninsula, and Severnaya Zemlya. There's sizable speculation on however these mountains area unit joined below the ocean. The second geologic process occurred throughout the Age of Reptiles (251 million to 65. 5 million years ago) and Cenozoic (the past 65. 5 million years) eras. These mountains survive in northeastern Siberia and Last Frontier. Horizontal or gently crooked matter rocks cowl a part of the protection in northern North American nation, wherever they're preserved in basins and troughs. Matter rocks area unit even a lot of in-depth in northern Russia and western and central Siberia, wherever they vary in age from early Paleozoic era to Quaternary (the past 2.6 million years).

It is evident that the polar landmasses are transported on lithospheric plates through time which their positions relative to every alternative and to the pole have been modified, with vital modification to ocean circulation and to climate. The motion of plates within the Paleogene and Neogene periods (about 65.5 million to 2.6 million years ago) LED to igneous activity in 2 regions. One was related to mountain building around the Pacific Ocean, and active volcanoes square measure still found in Kamchatka, the archipelago, and Alaska. The opposite space of igneous activity extended across the North Atlantic and enclosed the entire of Iceland, Jan Mayen Island, and east Kalaallit Nunaat south of Scoresby Sound; it absolutely was in all probability connected to west Kalaallit Nunaat north of Disko Bay and to east island. The geological phenomenon continues in Iceland and on Jan Mayen, and hot springs square measure found in Kalaallit Nunaat.

Continental ice sheets of the past

Little is understood concerning the climate of the northern lands in early geological era times; it's doable that the line was a minimum of 1,000 miles farther north than nowadays. Throughout the geological era, however, the polar lands became cooler and permanent land ice shaped, 1st within the Alaskan mountain ranges and afterward, by the top of the epoch (2.6 million years ago), in Greenland. By the onset of the Quaternary period, glaciers were widespread in northern latitudes. Throughout the Quaternary, continental-scale ice sheets enlarged and decayed on a minimum of eight occasions in response to major environmental condition oscillations in high latitudes. Elaborate info on the market for the ultimate glaciation (80,000 to 10,000 years ago) indicates that in North America the most ice sheet developed on the island and sweptback south and west across North American nation, amalgamating with smaller glaciers to create the Laurentide Ice Sheet, covering a lot of of the continent between the Atlantic and therefore the mountain range and between the ocean and therefore the Ohio and Missouri River valleys. A smaller ice cap-shaped within the Western Cordillera. The northern margin of the ice lay on the Brooks vary excluding the Yukon Basin and across the southern islands of the Canadian earth. To the north, the Queen Elizabeth Islands supported tiny, in all probability skinny, ice caps. Ice mass ice from Greenland crossed Nares Strait to succeed in Ellesmere Island throughout most glaciation.

The Atlantic Arctic islands were lined with ice except wherever isolated mountain peaks (nunataks) projected through the ice. In Europe, the Scandinavian Ice Sheet lined most of the geographical area between Severnaya Zemlya in Russia and also the British Isles. Northeastern geographical area free significant glaciation, although, as in northern North American country, the ice sheet had been additional in-depth in Associate in Nursing earlier glaciation.

As the ice sheets liquid, distinctive landforms developed by the ice were discovered. Though not restricted to this Arctic, they're usually distinguished there and, within the absence of forests, area units visible. In areas of crystalline rocks, as well as massive elements of the northern Canadian protect and Finland, the ice left disturbed drain and unnumberable lakes. Within the lowlands, deep glacial deposits stuffed scoured surfaces and created a sander landscape, usually broken by low ridges and hills of glacial material, drumlins, Rogen (ribbed) moraines, and eskers. Within the uplands, the characteristic glacial landforms area unit formed valleys. Close to the polar coasts, these are submerged to provide fjords, that area unit well developed in southern American state, on the geographic area of North American country, around Gronland, in east and west Iceland, on the coast of Norge, and several of the Arctic islands.

Because of their monumental weight, continental ice sheets depress the Earth’s crust. Because the ice sheets liquid at the shut of the Glacial epoch (11,700 years ago), the land slowly recovered its former altitude, however before this was completed the ocean flooded the coastal areas. resulting emergence has elevated marine beaches and sediments to extensive heights in several components of the Arctic, wherever their origin is well recognized from the presence of marine shells, the skeletons of ocean mammals, and wood. The best strandlines are found five hundred to 900 feet on top of modern water level in several components of the western and central Canadian Arctic and somewhat lower on the Baffin Bay and geographic area coasts. Comparable emergence is found on Svalbard, Greenland, the northern Urals, and on the Franz Josef terra firma, wherever it reaches over 1,500 feet. In several emerged lowlands, like those south and west of the sea, the raised beaches are the foremost conspicuous options within the landscape, forming many low, dry, gravel ridges within the otherwise ill-drained plains. In distinction, some Arctic coasts, notably around the Beaufort Sea, are experiencing immersion at the current time.

Polar continental shelves in areas that at large glaciation throughout the ice ages were exposed during times of low water level, particularly within the Bering Strait and ocean (Beringia), that expedited migration of individuals to North America from Asia, and within the Laptev and East Siberian seas.

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