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TitleGlacial and environmental geology of northeastern Manitoba
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorDredge, L A; Nixon, F M
SourceGeological Survey of Canada, Memoir 432, 1992, 80 pages (1 sheet), Open Access logo Open Access
MapsPublication contains 1 map
Map Info.surficial geology, surficial, 1:500,000
Mediapaper; on-line; digital
RelatedThis publication contains Surficial geology, northeastern Manitoba
File formatpdf
NTS54E; 54F; 54K; 54L; 54M
AreaNortheastern Manitoba; Churchill; Hudson Bay Lowlands; Churchill River
Lat/Long WENS-96.0000 -92.0000 60.0000 57.0000
Subjectsgeochemistry; surficial geology/geomorphology; environmental geology; wisconsinian glacial stage; glacial stages; sangamonian interglacial stage; interglacial stages; glaciation; sedimentation; till geochemistry; base metal geochemistry; gold geochemistry; uranium geochemistry; glacial lakes; glacial deposits; ice sheets; deglaciation; moraines; glacial features; eskers; tills; glacial history; permafrost; uranium; gold; glaciofluvial deposits; glaciolacustrine deposits; glaciomarine deposits; alluvial deposits; peat; ice movement directions; acid rain; land use; till geochemistry; sea level fluctuations; climatic fluctuations; climate; holocene; dispersal patterns; landforms; stratigraphic correlations; frost heaving; lithology; Tyrrell Sea; Glacial Lake Agassiz; Laurentide Ice-sheet; Keewatin Ice Sheet; Quaternary
Illustrationscross-sections; photographs; sketch maps; aerial photographs
Released1992 05 01; 2014 10 03
AbstractQuaternary deposits in northeastern Manitoba are related to pre-Wisconsin and Wisconsin glaciations, the Sangamon Interglaciation ,and postglaciallakes and seas. During the Wisconsin Glaciation, the map area was continually glaciated by Laurentide ice from two centres of outflow. Keewatin ice flowed southward and deposited a sandy to bouldery granitic till sheet, the surface of which is divided into belts of rib moraine and crevasse fillings. A second ice mass, centred over Hudson Bay, flowed westwards and deposited several silty calcareous till sheets, the uppermost of which is gently ridged by grounding-line moraines. The position of convergence of the two ice masses varied during the course of glaciation. A major segmented interlobate kame moraine, which was deposited largely during de glaciation, marks the final confluence. Lake Agassiz covered the area vacated by the receding glaciers and persisted as long as ice sheets blocked drainage into Hudson Bay. Turbidite sands and varved or massive clays deposited into this water body cover the southern part of the region. Hudson ice disintegrated suddenly about 7800 (or 8000) BP, and the glacioisostatic Tyrrell Sea flooded areas below 180 m elevation; the land continues to emerge at a rate of 40 cm per century. A major raised beach, formed about 7200 BP, constitutes a major aggregate deposit. Icy muskeg forms the terrain south of Seal River. Frost-riving of bedrock and aggradation or degradation of ground ice are current periglacial processes. Areas east of the Great Beach lie within the zone of continuous permafrost; those to the west lie in discontinuous permafrost. Because ground temperatures are near 0 C, the region is extremely sensitive to climatic or man-induced changes in thermal regime: a small change in ground temperature can produce major terrain disturbances. Permafrost has also limited the buffering capacity of the soils to counteract the effects of acid rain. The surface till sheet has anomalously high concentrations of uranium north of Seal River and interesting gold associations near Great Island.

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