Laurentide Ice Sheet

The Laurentide Ice Sheet was a massive   sheet of ice that covered millions of square kilometers, including most of   Canada and a large portion of the northern United States, multiple times   during the Quaternary glacial epochs— from 2.588 ± 0.005 million years ago to   the present.[1] The last advance covered most of northern North America   between c. 95,000 and c. 20,000 years before the present day, and among other   geomorphological effects, gouged out the five Great Lakes and the hosts of   smaller lakes of the Canadian shield. These lakes extend from the eastern   Northwest Territories, through most of northern Canada, and the upper   Midwestern United States (Minnesota, Wisconsin, and Michigan) to the Finger   Lakes, through Lake Champlain and Lake George areas of New York, across the   northern Appalachians into and through all of New England and Nova Scotia. At   times, the ice sheet's southern margin included the present-day sites of   northeastern coastal towns and cities such as Portsmouth, New Hampshire,   Boston, and New York City, and Great Lakes coastal cities and towns as far   south as Chicago and St. Louis, Missouri—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. The ice   coverage extended approximately as far south as 38 degrees latitude in the   mid-continent.[2]

劳伦泰冰原

劳伦泰冰原是一块巨大的冰盖，在第四纪冰川时期，从2588±0.05万年前到现在，多次覆盖了数百万平方公里，包括加拿大大部分地区和美国北部的大部分地区。据今95000年和20000年前，该冰盖的发展，覆盖了北美洲大部分地区，加上其它的一些地质作用，挖出了五大湖和加拿大地盾大量较小的湖泊。这些湖泊从西北地区的东部延伸，经过加拿大北部的大部分地区，以及美国中西部的上部地区（明尼苏达州、威斯康星州和密歇根州），到芬格湖，穿过纽约的Champlain湖和乔治湖地区，穿过阿巴拉契亚北部，进入并穿过整个新英格兰和新斯科舍省。有时，冰盖的南缘包括现在东北部沿海城镇和城市的遗址，如朴茨茅斯、新罕布什尔、波士顿和纽约市，以及五大湖沿岸城市和城镇，最南边是芝加哥和密苏里州的圣路易斯，然后非常精确地沿着密苏里河的当前河道一直延伸到他把柏树山的北坡与科迪勒拉山脉的冰原融为一体。在中大陆，冰的覆盖范围大约向南延伸到纬度38度。