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26-746: The Ager emerged towards the end of the Würm glaciation , when the mighty glaciers began to melt. Influx into the Ager: Over the Attersee the Ager also receives water from the Mondsee , the Irrsee (also called Zeller See), and the Fuschlsee , that are all connected by relatively short streams. In the postwar period, the Ager was strongly polluted by various nearby factories. Today this

52-409: A lower portion of the moraine. Multiple outlets could form through low spots too until one would become dominant after erosion lowered both the outlet and lake surface. Ice melt and rainfall carried large quantities of clay , sand , and gravel from the ice mass. Clays could be moved long distances by moving water, while sand and gravel could not. Thus, sand and gravel landforms developed along

78-898: A result, the Illinoian Stage is only temporally equivalent to either middle and late Wolstonian stage or late Wolstonian stage in the British Isles. In North America, the term "Wolstonian stage" is not used by geomorphologists and Quaternary geologists to designate glacial deposits and paleosols lying between the Sangamon and Yarmouth soils ( paleosols ). During the Illinoian Stage, the Laurentide Ice Sheet covered about 85 percent of Illinois. At its maximum extent during this stage, this ice sheet reached its southernmost extent in North America near Carbondale, Illinois . At their maximum extent,

104-468: A whole. The striations made by the ice field in moving over the bedrock show that it moved principally to the west through the passes of the coast range. Whenever the ice sheet melted from the north at a moraine , water would begin to pond in the divide between a moraine and the ice front. The ice would act as a dam as water could not drain through the ice sheet, which in the Wisconsin period covered most of

130-754: Is defined as the period of geologic time during which the glacial tills and outwash , which comprise the bulk of the Glasford Formation, accumulated to create the Illinoian Glacial Lobe. At its type exposure in Peoria County , Illinois , the Illinoian deposits consist of three till members of the Glasford Formation. They overlay Pre-Illinoian tills of the Banner Formation, in which

156-526: Is less the case because several sewage treatment plants have been created. This Upper Austria location article is a stub . You can help Misplaced Pages by expanding it . This article related to a river in Austria is a stub . You can help Misplaced Pages by expanding it . Wisconsin glaciation The Wisconsin glaciation , also called the Wisconsin glacial episode , was the most recent glacial period of

182-732: Is the name used by Quaternary geologists in North America to designate the Penultimate Glacial Period c.191,000 to c.130,000 years ago, during the late Middle Pleistocene (Chibanian), when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes the Sangamonian Stage (corresponding to the global Last Interglacial ) and follows the Pre-Illinoian Stage in North America. The Illinoian Stage

208-560: The Bering Strait is believed to have allowed human occupation of this area which provided potential access for some of the first humans to move between North America and Siberia in Asia (see Settlement of the Americas ). Other human migration routes also opened during interglacial periods in both Europe and Asia. North American flora and fauna species were distributed quite differently during

234-815: The Late Wisconsin in North America. This glaciation radically altered the geography north of the Ohio River , creating the Great Lakes . At the height of the Wisconsin Episode glaciation, the ice sheet covered most of Canada , the Upper Midwest , and New England , as well as parts of Idaho , Montana , and Washington . On Kelleys Island in Lake Erie , northern New Jersey and in New York City 's Central Park ,

260-558: The Waterman Hills researchers found that Juniperus osteosperma and Pinus monophylla were early to mid-Holocene dominant trees, while Monardella arizonica has been a continuously present understory plant. Celtis reticulata is an example of a plant present in the early Holocene following Wisconsin glacial retreat, a species no longer present at the Waterman Mountains site. Illinoian The Illinoian Stage

286-641: The Yarmouth Soil ( paleosol ) has developed. In this exposure, the Illinoian Glasford Formation, in which the interglacial Sangamon Soil (palesosol) has developed, is overlain by early Wisconsinan stage loess , called the Roxana Silt . A paleosol, called the Pike Soil , separates two of the till members within the Glasford Formation. The Illinoian Stage is further subdivided into: Since 1986,

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312-482: The fluvial deposits of the Pearl Formation and Illinoian glacial tills of the Glasford Formation, which fill an ancient and buried Mississippi River valley in north-central Illinois, demonstrated that the Illinoian Stage in its type area consists of glaciations that occurred only during Marine Isotope Stage 6. The age of proglacial fluvial sediments underlying the oldest known glacial till ( Kellerville Member ) of

338-671: The grooves left in rock by these glaciers can be easily observed. In southwestern Saskatchewan and southeastern Alberta a suture zone between the Laurentide and Cordilleran ice sheets formed the Cypress Hills , North America's northernmost point that remained south of the continental ice sheets. During much of the glaciation, sea level was low enough to permit land animals, including humans , to occupy Beringia (the Bering Land Bridge ) and move between North America and Siberia . As

364-718: The Canadian Territory of Keewatin . The ice moved south some 1,500 miles (2,400 km) into Kansas and Missouri. To the west, it reached 1,000 miles (1,600 km) to the foothills of the Rocky Mountains . The Cordilleran Ice Sheet has left remnants throughout the Northern Rocky Mountains . Unlike the other two ice sheets, this one is mountain based covering British Columbia and reaching into northern Washington State and Montana . The Cordilleran Ice Sheet has more of an Alpine style of many glaciers merged into

390-408: The Glasford Formation yield optically stimulated luminescence (OSL) dates that averaged 160,000 BP . The oldest fluvial sediments, which overlay bedrock in the deepest part of the valley, were dated by OSL dating to around 190,000 BP. These OSL dates demonstrate that the Illinoian Stage is temporarily equivalent only to Marine Isotope Stage 6, which ended at 130,000 BP and started at 191,000 BP. If

416-552: The Illinoian Stage has been interpreted as consisting of two glaciations, the early Illinoian ( Marine Isotope Stage 8) and late Illinoian glaciations (Marine Isotope Stage 6) and the intervening interglacial period (Marine Isotope stage 7). In this interpretation, the Pike Soil is proposed to an interglacial (Marine Isotope Stage 7) paleosol. According to this interpretation, the Illinoian Stage started about 300,000 years ago and ended about 130,000 years ago. However, later studies of

442-632: The Illinoian Stage is limited in duration to Marine Isotope Stage 6, the Yarmouth Soil (paleosol) spans a period of geologic time equivalent to Marine Isotope stages 7, 8, 9, 10, and 11. The Illinoian Stage in North America is not exactly equivalent to the Wolstonian Stage of the British Isles . The Wolstonian stage is equivalent to Marine Isotope stages 6, 7, 8, 9, and 10. and, thus, started about 352,000 years ago and ended 130,000 years ago. As

468-712: The North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet , which nucleated in the northern North American Cordillera ; the Innuitian ice sheet , which extended across the Canadian Arctic Archipelago ; the Greenland ice sheet ; and the massive Laurentide Ice Sheet , which covered the high latitudes of central and eastern North America. This advance

494-476: The Wisconsin era, due to altered temperatures, surface water distribution, and in some cases coverage of earth surface by glaciers. A number of scientific studies have been conducted to determine species distribution, particularly during the Late Wisconsin and early to mid-Holocene. An example of findings is from the investigation of flora species using pollen core samples in present-day northern Arizona. Here in

520-499: The glacial deposits were eroded and weathered. This first Wisconsin period erased all the Illinoian glacial topography that its glaciers extended over. The Late Wisconsin ice sheet extended more towards the west than the earlier movements. This may have been due to changes in the accumulation center of the ice sheet, topographic changes introduced by the Early phase or by pressure changes in

546-427: The glacier when it melts back is called the ground moraine or till plain . Till is highly permeable and creates a large ground reserve for water. This formation is highly desirable for human economic development as a source of water. Prehistoric human migration was likely greatly influenced by this last glacial period, as during much of the Wisconsin era, the formation of a land bridge known as Beringia across

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572-577: The glaciers retreated, glacial lakes were breached in great glacial lake outburst floods such as the Kankakee Torrent , which reshaped the landscape south of modern Chicago as far as the Ohio and Mississippi Rivers. Two related movements have been termed Wisconsin: Early Wisconsin and Late Wisconsin. The Early Wisconsin was the bigger of the two and extended farther west and south. It retreated an unknown distance before halting. During this period of quiet,

598-475: The ice mass in the north. The Labrador Ice Sheet centered east of Hudson Bay. Expanding towards the southwest, it reached into the eastern edge of Manitoba and across the Great Lakes to the Ohio River , upwards of 1,600 miles (2,600 km) from its source. Its eastern lobes covered New England and reached south to Cape Cod and Long Island, New York . The Keewatin Ice Sheet began west of Hudson Bay in

624-423: The proglacial river valleys. Numerous small, isolated water bodies formed between the moraine and the ice front. As the ice sheet would continue to melt and recede northward, these ponds combined into proglacial lakes . In areas without an available outlet, the water levels would either continue to rise until reaching one or more low spots along the rim of a moraine, or the ice sheet would retreat, opening access to

650-409: The sides and front of the ice sheet; elongated accumulations of this material are known as kames . Mounds along the frontal edge of the ice are called moraines . Wherever a subglacial tunnel began infilling, long winding formations known as eskers would form. The sweeping plain of sand and gravel beyond the ice margin and a terminal moraine is called an outwash plain . The materials left under

676-521: Was synchronous with global glaciation during the last glacial period, including the North American alpine glacier advance, known as the Pinedale glaciation . The Wisconsin glaciation extended from about 75,000 to 11,000 years ago, between the Sangamonian Stage and the current interglacial, the Holocene . The maximum ice extent occurred about 25,000–21,000 years ago during the last glacial maximum , also known as

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