Laurentian Upland
1954 Series
.The Laurentian Upland (or Laurentian Highlands) is a
Grenville geological province, 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
Mont Raoul Blanchard
is the highest peak.
Although the other limits are less well defined, this Laurentian Region in Quebec may be considered to extend 100–200 km northward from the 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
Superior Upland.[5] As a southern extension of the Canadian Shield, the Adirondack Mountains of New York State might also be considered an extension of the Laurentian Upland.[6]
Geology
The Laurentian Upland is primarily made up of ancient
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]
Superior Upland
Superior Upland
is identified by "1" on the map.
The
monadnocks left behind during the peneplanation of the rest of the surface. The erosion of the region must have been far advanced in prehistoric times, even practically completed, because the even peneplain surface is overlapped by fossiliferous marine strata from an early geological date, Cambrian. This shows that the depression of the region beneath an ancient sea took place after a long existence as dry land.[11]
The extent of the submergence and the area over which the
Palaeozoic
strata were deposited are unknown. Because of the renewed elevation without deformation, erosion in later periods has stripped off an undetermined amount of the covering strata. The valleys by which the uplands are here and there trenched to moderate depth appear to be, in part at least, the work of streams that have been superposed upon the peneplain through the now removed cover of stratified rocks.
Glaciation
has strongly scoured away the deeply weathered soils that presumably existed here in preglacial time. It left behind firm and rugged ledges in the low hills and swells of the ground and spread an irregular drift cover over the lower parts, whereby the drainage is generally disordered being deposited in lakes and swamps and elsewhere rushing down rocky rapids.
See also
- Laurentian Mountains
- Opeongo Hills
- Adirondack Mountains
- Misquah Hills
- Huron Mountains
- Porcupine Mountains
References
- ^ "The Atlas of Canada" (PDF). Natural Resources Canada. Archived from the original (PDF) on 2008-02-16. Retrieved 2007-12-27.
- ^ Physiographic divisions of the conterminous U. S
- ^ Physiographic Regions Archived 2006-05-15 at the Wayback Machine
- ^ "Mesaba Energy Project, Joint Permit Application" (PDF). Minnesota Public Utilities Commission. Archived from the original (PDF) on 2006-10-09. Retrieved 2007-12-27.
- ^ "USGS Geology in the Parks". Archived from the original on 2013-05-12. Retrieved 2008-05-18.
- ^ 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.
- ISBN 0-8166-0953-5.
- ^ Lajoie, Paul G. (1962). Soil Survey of Gatineau and Pontiac Counties, Quebec. Canada Department of Agriculture. p. 14.
- ^ Frank, Dave. "USGS Geology and Geophysics". geomaps.wr.usgs.gov. Archived from the original on 2013-05-12. Retrieved 2008-05-18.
- ^ U.S. Geological Survey. (various quadrangles) [maps]. 1:50,000. Washington D.C.: USGS, 1971
- ISBN 0-8166-0953-5.