Unconsolidated deposits on the surface of Paleozoic-age limestone
These are unconsolidated deposits on the surface of an isolated outcrop of Paleozoic-age limestone north of Aberdeen Lake in the former District of Keewatin. The surface here consists mostly of limestone chips in a silty clay matrix, and actual outcrops of the bedrock are rare. The approximate location of this several-acre isolated outcrop, which lies on top of late Precambrian-age rocks of the Thelon Basin, is at 64° 30' N latitude and 98° 30' W longitude. Its general location and an aerial photo of the outcrop and its dispersal train are shown in a previous publication (figures 1, 3, and 4; Aylsworth and Shilts, 1989b). The typical tundra vegetation of this region does not thrive on this alkaline substrate because most tundra plants are acidophilic, and there are few carbonate bedrock units within the Precambrian terranes that underlie much of the Canadian lower arctic tundra. I am not sure what the clumps of vegetation are in this image, but, as I recall, only caribou moss can tolerate the rare alkaline soil conditions of the tundra regions of the Canadian Shield. See also image 0110.
Updated 03/30/2010 AW