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The Laurentide ice sheet was a massive sheet of ice that covered hundreds of thousands of square miles, including most of Canada and a large portion of the northern United States, between ~ 90,000 and ~ 18,000 years before the present day. Its southern margin included the modern sites of New York City and Chicago, and then followed quite precisely the present course of the Missouri River up to the northern slopes of the Cypress Hills, beyond which it merged with the Cordilleran Ice Sheet An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²). The only current ice sheets are Antarctic and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada...
Midtown Manhattan, looking north from the Empire State Building, 2005 New York City (officially named the City of New York) is the most populous city in the United States, and is at the center of international finance, politics, entertainment, and culture. ...
Chicago (officially named the City of Chicago) is the third largest city in the United States (after New York City and Los Angeles), with an official population of 2,896,016, as of the 2000 census. ...
The Missouri River and its tributaries N.P. Dodge Park, Omaha, Nebraska High silt content makes the Missouri (left) noticeably lighter than the Mississipi here at their confluence above St. ...
The Cypress Hills are a region of hills in southwestern Saskatchewan and southeastern Alberta, Canada. ...
The Cordilleran ice sheet was a major ice sheet that covered, during glacial periods of the Quaternary, a large area of North America. ...
Up to two miles thick in Nunavik but much thinner at its edges where nunataks were common in hilly areas, this ice sheet was the primary feature of the North American ice age. The Nunavik Region of Quebec, Canada Nunavik (ᓄᓇᕕᒃ) is a region making up the northern third of the province of Quebec, Canada. ...
A nunatak is a mountain top that never has been covered by land ice (glaciation, ice age) or glaciers. ...
Its cycles of growth and melting were a decisive influence on global climate during its existence. This is because it served to divert the jet stream which would otherwise flow from the relatively warm Pacific Ocean through Montana and Minnesota to the south. This gave the southwestern United States, otherwise a desert, abundant rainfall during ice ages - in extreme contrast to most other parts of the world which became exceedingly dry, though the effect of ice sheets in Europe had an analogous effect on the rainfall in Afghanistan, parts of Iran, and possibly western Pakistan (only in winter) and North Africa. Jet streams are fast flowing, confined air currents found in the atmosphere at around 12 km above the surface of the Earth, just under the tropopause. ...
State nickname: Treasure State Other U.S. States Capital Helena Largest city Billings Governor Brian Schweitzer (D) Official languages English Area 381,156 km² (4th) - Land 377,295 km² - Water 3,862 km² (1%) Population (2000) - Population 902,195 (44th) - Density 2. ...
State nickname: North Star State Other U.S. States Capital Saint Paul Largest city Minneapolis Governor Tim Pawlenty (R) Official languages None Area 225,365 km² (12th) - Land 206,375 km² - Water 18,990 km² (8. ...
In many parts of the world, winter is associated with snow. ...
North Africa is a region generally considered to include: Algeria Egypt Libya Mauritania Morocco Sudan Tunisia Western Sahara The Canary Islands, Ethiopia, Eritrea, Azores and Madeira are sometimes considered to be a part of North Africa, though they do not share a common culture with the countries listed above. ...
Its melting also caused major disruptions to the global climate cycle, because the huge influx of low-salinity water into the Atlantic Ocean initially via the Susquehanna River and later via the Saint Lawrence is believed to have disrupted the circulation of water from south to north in the Atlantic, creating the brief Younger Dryas cold epoch and a brief re-advance of the ice sheet, which did not retreat from Nunavik until 6500 years ago. The Susquehanna River is a river in the northeastern United States, approximately 410 mi (715 km) long. ...
The Saint Lawrence River (French: fleuve Saint-Laurent) is a large west-to-east flowing river in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. ...
The Younger Dryas stadial, named after the alpine / tundra wildflower Dryas octopetala, and also referred to as the Big Freeze [1], was a brief cold climate period following the Bölling/Allerød interstadial at the end of the Pleistocene, and preceding the Preboreal of the early Holocene. ...
Some people have controversially argued that huge influxes of fresh water stopped the feeding of the ice sheet and starved it, aiding the retreat that had already began. This is a controversial position because it is known that the North Atlantic was very cold throughout glacial periods and it is likely that the anticyclone on top of the ice sheet helped sustain it through moist easterly winds which encouraged snow-bearing winds from the south. In glaciology, starvation is said to occur when a glacier retreats not because of temperature increases, but due to precipitation being so low that ice flow downwards into the zone of ablation exceeds the replenishment from snowfall. ...
In meteorology, an anticyclone is a weather phenomenon associated with atmospheric high pressure. ...
During the Kansan Glaciation the Laurentide Ice Sheet extended even further south, reaching as far as Douglas County, Kansas and almost as far as St. Louis, Missouri. The Kansan Glaciation (known in UK as the Anglian Glaciation and sometimes referred to as the Illinoian Glaciation, Elster glaciation in northern Europe and the Mindel glaciation in the Alps) was a very severe glacial period in the Pleistocene. ...
Douglas County (standard abbreviation: DG) is a county located in the state of Kansas. ...
The Gateway Arch, shown here behind the Old Courthouse, is the most recognizable part of the St. ...
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