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TitleThe enigmatic rings of the James Bay Lowland: a probable geological origin
AuthorVeillette, J J; Giroux, J F
SourceGeological Survey of Canada, Open File 3708, 1999, 40 pages, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediapaper; on-line; digital
File formatpdf
ProvinceOntario; Quebec
NTS32; 42; 52A; 52B; 52G; 52H; 52I; 52J; 52O; 52P
AreaLake St. Joseph; Hearst; Cochrane; Timmins; Matagami; James Bay Lowlands
Lat/Long WENS -92.0000 -72.0000 52.0000 48.0000
Subjectsgeochemistry; surficial geology/geomorphology; landforms; vegetation; carbonate rocks; sedimentary rocks; soil studies; peat; Picea mariana; trees; Phanerozoic; Cenozoic; Quaternary
Illustrationssketch maps; aerial photographs
Released1999 02 01; 2017 02 23
AbstractA survey of airphotos for a large band of Eastern Canada extending from Manitoba to Newfoundland between Lat. 48° N and 52° N has revealed a massive concentration of whitish ring-shaped features, a few tens of metres up to 2 km in diameter, in the organic, black spruce-covered, poorly drained terrain of the James Bay and Hudson Bay Lowland, and on Anticosti Island in the Gulf of Saint Lawrence. The light-coloured tone is related to the more open tree cover and the presence of annular bogs within the rings which contrasts with the surrounding denser tree cover. Ground investigation has shown that the rings coincide with shallow annular depressions in the mineral soil that have been infilled with peat, or covered by shrubs and trees that can tolerate a water table close to the surface. The origin of the rings is considered by some to be the result of biological processes and by others, of geological processes. The radial expansion of a fungus that infects and kills trees thus producing rings in the vegetation, is the basis for the biological hypothesis, while geochemical processes in the soil related to the underlying bedrock geology is the basis for the geological hypothesis. A detailed botanical and dendrochronological investigation carried out in 7 rings in northern Abitibi does not support the radial expansion model and shows that the rings are static features. The rings form a belt extending from north of Lake Nipigon to western Quebec, that closely correlates with the extent of calcareous soils. This, along with the presence of shallow depressions in the calcareous substrate beneath the rings, and the lack of periglacial or geological processes at the surface that could account for the rings, suggest mechanisms acting from below. The depressions may result from carbonate depletion related to geochemical mechanisms in the soil generated at depth in the bedrock geology. Thick, up to 3 m, peat sequences in some annular bogs indicate that the depressions beneath the rings have been formed hundreds, perhaps thousands of years ago, to allow that much peat to accumulate. Thus, the rings have been stationary for long periods of time.