Laurentian Upland

A scene of the Laurentians based on a photograph from the Provincial Publicity Bureau of Quebec engraved by William Ford was on the $20 banknote of the 1954 Series.

The Laurentian Upland (or Laurentian Highlands) is a physiographic region which, when referred to as the "Laurentian Region", is recognized by Natural Resources Canada as one of five provinces of the larger Canadian Shield physiographic division.[1] The United States Geological Survey recognizes the Laurentian Upland as the larger general upland area of the Canadian Shield.[2][3][4]

Geography

The Laurentian Region, as recognized by Natural Resources Canada, is part of the plateau and dissected southern rim of the Canadian Shield in the province of Québec. It is a western extension of the Laurentian Mountains, and continues across the Ottawa Valley into Ontario as the Opeongo Hills. Viewed from the valleys of the Ottawa and St. Lawrence Rivers, the south-facing escarpments of the Shield give the appearance of mountains 500–800 meters high; looking across the plateau, the relief is more moderate and subdued. These scarps mark the dramatic southern edge of this Upland region, of which Mont Raoul Blanchard is the highest peak at roughly 1,166 meters (3,825 ft).

Although the other limits are less well defined, this Laurentian Region in Quebec may be considered to extend 100–200 km northward from the scarps and to stretch from the Gatineau River in the west (mean elevation 400 m) some 550 km to the Saguenay River in the northeast. Here it attains its maximum elevation north of Quebec City in the Réserve faunique des Laurentides (over 1000 m). Individual summits rise above the plateau surface: Mont Sir Wilfrid (783 m) and Mont Tremblant in the west, Mont Sainte-Anne (815 m) at Quebec, Mont Raoul Blanchard (1166 m), Mont Bleu (1052 m) and Mont des Conscrits (1006 m) in Réserve faunique des Laurentides. Cap Tourmente (579 m) and Mont des Éboulements (770 m) are dramatic examples of the scarp face as it drops precipitously to the St Lawrence River.

The more general Laurentian Upland Province may be considered to extend over a larger area of the Canadian Shield, into Northwestern Ontario and parts of Northern Minnesota, Wisconsin, Michigan, and New York State, and is recognized by the United States Geological Survey to include the Superior Upland.[5] As a southern extension of the Canadian Shield, the Adirondack Mountains of New York State might also be considered and extension of the Laurentian Upland.[6]

Geology

The Laurentian Upland is primarily made up of ancient Precambrian igneous, metamorphic, and sedimentary rock.[7] With the exception of the river valleys and lacustrine basins, it is a rolling to mountainous peneplain that ranges from 800 to 1400 feet above sea level.[8]

See also

References

  1. ↑ "The Atlas of Canada" (PDF). Natural Resources Canada. Retrieved 2007-12-27.
  2. ↑ Physiographic divisions of the conterminous U. S
  3. ↑ Physiographic Regions
  4. ↑ "Mesaba Energy Project, Joint Permit Application" (PDF). Minnesota Public Utilities Commission. Retrieved 2007-12-27.
  5. ↑ USGS Geology in the Parks
  6. ↑ Erwin Raisz, Physiographical Map of North America, in Espenshade, Edward B., Jr., and Joel L. Morrison, editors. Goode's World Atlas, 17th ed. Chicago: Rand McNally & Co. 1986.
  7. ↑ Ojakangas, Richard W.; Matsch, Charles L. (1982). Minnesota's Geology. University of Minnesota Press. p. 15. ISBN 0-8166-0953-5.
  8. ↑ Lajoie, Paul G. (1962). Soil Survey of Gatineau and Pontiac Counties, Quebec. Canada Department of Agriculture. p. 14.

Coordinates: 46°26′N 74°59′W / 46.433°N 74.983°W / 46.433; -74.983

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