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TitleCarbonate Till As a Soft Bed For Pleistocene Ice Streams On the Canadian Shield North of Lake Superior
AuthorHicock, S R; Kristjansson, F J; Sharpe, D RORCID logo
SourceCanadian Journal of Earth Sciences vol. 26, no. 11, 1989 p. 2249-2254,
Alt SeriesGeological Survey of Canada, Contribution Series 27187
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
NTS43B; 43C; 43D; 43E; 43F; 43G; 53A; 53B; 53C; 53D; 53F; 53G; 53H; 52; 42; 41I; 41J; 41O; 41P
AreaNorthern Ontario
Lat/Long WENS -95.0000 -80.0000 54.0000 46.0000
Subjectssurficial geology/geomorphology; tills; glacial deposits; pleistocene; carbonate rocks; sedimentary rocks; models; ice sheets; ice movement; dispersal patterns; ice movement directions; moraines; ice thickness; Superior Province; Laurentide Ice-sheet; Quaternary
Illustrationssketch maps
Released1989 11 01
AbstractSilty carbonate till derived from erosion of Paleozoic carbonate and Proterozoic rocks within and adjacent to Hudson Bay covers extensive areas of the Canadian Shield north of Lake Superior. It is hypothesized that this carbonate till could have acted as low-resistance substrata for overriding ice streams by deforming and (or) supporting high subglacial water pressures. Contrary to assumptions presented in some current models for ice flow within the Laurentide Ice Sheet, it need not be assumed that Shield terrain in these areas acted as a rigid bed, generating large basal shear stresses and inhibiting ice flow. Indeed, erratic-dispersal patterns, long-distance glacial transport, and splayed patterns of ice-flow indicators in areas of thick till cover may be better explained by rapid ice-flow events or ice streams, enhanced by the thickness, distribution, impermeability, and susceptibility to deformation of fine carbonate till.

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