The Columbia Icefield was formed during the Great Glaciation, or Illinoisan period (238,000 to 126,000 BCE). The initial advancement of the ice field ended during the latter millennia of the Early Wisconsinan period (73,000 to 62,000 BCE), around the time Homo sapiens began to appear on the earth. The next major advance of the ice field occurred during the Late Wisconsinan period (18,000 to 9,000 BCE), which marked the end of the major intercontinental land mass bridges. During the Crowfoot Glacier advance (9,000 to 7,000 BCE), humans were beginning to learn farming along the Tigris, Euphrates, and Nile rivers. The last major period of advance occurred during the Little Ice Age, which lasted from about 1,200 to 1900 AD. Around 1800, the Athabasca Glacier peaked, then went through a period of recession, and then advanced again until 1840, when it began receding until the present day.