II.

Geologic Activity

At the beginning of the Holocene Epoch ice covered much of North America, Scandinavia, and other northern and southern latitude and high altitude regions of the world. The ice was melting rapidly, and substantial glacial lakes, including ancestors of the Great Lakes of the United States and Canada, formed at the edge of melting glaciers. The world’s climate warmed extremely rapidly in the early Holocene Epoch, and by 8000 years before the present temperatures in the middle latitudes of the earth neared today’s temperatures.

By about 6500 years before present the last remnants of the Laurentide Ice Sheet, which had covered most of Canada, finally vanished from either side of Hudson Bay. Afterward, the only continental ice existed at high altitudes and northerly latitudes. Plant and animal communities rapidly colonized the landscape revealed by retreating ice sheets. Humans have modified some of the natural landscape, most substantially in the last two hundred years.