ABSTRACT: Preliminary surficial geology of Cornwallis Island and adjacent islands, Northwest Territories

CGRG Bibliography of Canadian Geomorphology
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Abstract

The landforms of the Cornwallis Island area are primarily the result of pre-Pleistocene planation and dissection. Faulting during a late Cretaceous-Tertiary rifting episode created the surrounding channels and major valleys on Cornwallis and Griffith islands. The most widespread surface materials are carbonate rock and its weathered product, residuum. Beach deposits characterize the coasts of the major islands and completely cover small, low lying islands. There is scattered evidence of Quaternary glaciation, but glacial deposits and features are a minor part of the landscape. Scattered shield erratics and remnants of erratic-rich till indicate that the area was covered by continental ice, probably during pre-Late Wisconsinan times. During the Late Wisconsinan the area was affected by two types of ice masses: 1) the edge of the Laurentide Ice Sheet, which probably extended only onto Lowther Island and 2) a local ice cap(s) over Cornwallis Island. Marine transgression as a result of Late Wisconsinan deglaciation reached to about 120 m.a.s.l. in the southern part of the study area and to less than 100 m in the north. The surficial materials of the Cornwallis Island area are among the least sensitive to disturbance in the High Arctic islands; most areas are traversible. Environmental damage can be minimized by avoiding wet, fine grained materials and vegetated areas. All activities should be curtailed during spring thaw and after heavy summer precipitation. Beach deposits provide an abundant source of gravel, and the carbonate formations are a widespread, potential gravel source. Sand resources are limited.

Bibliography of Canadian Geomorphology