The last continental ice sheet had three main component parts, the Laurentide Ice Sheet, the Cordilleran Glacier Complex, and the Queen Elizabeth Islands Glacier Complex. The Laurentide Ics Sheet is commonly regarded, on the basis of ice-flow patterns, as comprising the Labrador and Keewatin sectors which, although confluent at the Wisconsin glacialmaximum, became discrete areas of outflow during deglaciation. The former retreated to one or more centres or ice divides in northern Quebec and Labrador, and the latter to an ice divide west of Hudson Bay. These major areas of late ice flow themselves split up into smaller short-lived units of outward-flowing ice prior to the final dissipation of the main remnants. Deglaciation also resulted in other major components of Laurentide Ice Sheet. An ice sheet remained and was nurtured locally in Foxe-Baffin Glacier Complex, was independant of the Keewatin and Labrador sectors at least in late Wisconsin time, and parts remain today. Also, early in the deglacial process, major independent ice caps formed in the Appalachian regions, for instance, in Newfoundland, and in part may have been independant of the Labrador sector throught most of the Wisconsin.
As the ice sheets and glaciers waned and the land surface was uncovered, the forms implanted by the ice were left exposed or were covered by glacial debris waqshed out from the receding ice margins on land, in lakes or in the sea. The complex record of glacial and postglacial features and deposits remaining today afford a means of tracing the paths of the receding ice margins and interpreting the deglacial and postglacial patterns.