ABSTRACT: Karst hydrogeology within a subarctic peatland: Attawapiskat River, Hudson Bay Lowland, Canada

CGRG Bibliography of Canadian Geomorphology
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Abstract

The Attawapiskat River cut through 30 m of mid-Silurian limestone approximately 90 km west of James Bay in the Hudson Bay Lowland. Limestone cliffs of 12-15 m provide local relief along the river but inland the terrain is flat, covered by 1.5 m or more of peat. The area emerged from the Tyrrell Sea approximately 4400 yr. B.P. Since that time two karst hydrogeological zones have become established: a vadose fluvio-karst zone in the exposed limestone along the river represented by disappearing lakes and streams; and an organo-karst zone represented by sinkholes on or next to limestone bioherms within the peat mantle. They occupy 16% and 13% of the study area, respectively. Organo-karst features are expected to expand at the expense of the peatland. Three karst morphologies have evolved. The first morphology occurs where the top of the knoll is higher than the surrounding bog; dolines, often with intermittent ponds or small lakes form at the edge of the reef. The second morphology occurs where the reef surface is at the same elevation as the surrounding peatland; the bog may encroach onto the reef. The third morphology develops where the reef surface is lower than the surrounding peatland; the bog may drain into the reef.

Bibliography of Canadian Geomorphology