CGRG Bibliography of Canadian Geomorphology
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Author : Andrews, J.T.; and Ives, J.D.
Date : 1978
Title : `Cockburn' nomenclature and the Late Quaternary history of the eastern Canadian Arctic
Publication : Arctic and Alpine Research
Issue : 10(3):
Page(s) : 617-633
Abstract
A system of end and lateral moraines, extending from near Frobisher, Baffin Island, to the west of the Penny Ice Cap, and roughly parallel to the fiord heads of the northeast coast to Bernier Bay, was identified in the 1960s and given the name "Cockburn end-moraine system." Since then the name "Cockburn" has been used in conjunction with several distinct types of stratigraphic units and landform assemblages. The three main uses are (1) Cockburn end-moraine system, Cockburn moraines, Cockburn Moraine, which are all morphostratigraphic units; (2) Cockburn Stade, which is a geologic-climatic unit; and (3) Cockburn Glacial Phase, which was originally defined as occurring between 8000 and 9000 radiocarbon years ago, and which is therefore, a chronostratigraphic unit. Thus there is an ambiguity in present usage that has developed over the last 15 yr as knowledge of the glacial morphology and stratigraphy of the eastern Canadian Arctic has expanded. In this paper an attempt is made to reduce this ambiguity by preparing new definitions. Cockburn Substage. A chronostratigraphic division of the Holocene Series based upon radiocarbon-dated sediments between 8000 and 9000 BP. Analysis of available radiocarbon dates, all on marine shells, indicates that the original definition of the "Cockburn Glacial Phase" is sufficiently within the possible margin of dating errors and stratigraphic content to warrant retention of the time span prior to the disintegration of the Laurentide ice sheet may have readvanced to reach its maximum late-glacial extent. Moraines deposited between 8000 and 9000 BP can properly be referred to as "moraines of Cockburn age." Baffinland Drift. This litho-/morphostratigraphic unit replaces "Cockburn end-moraine system," as originally described, and synonymous terms. The Baffinland Drift includes the complex of moraines, till, outwash deposits, and glaciomarine deposits that together for the recognizable and mappable unit paralleling the fiord heads of northeastern Baffin Island. It can be differentiated from older Quaternary units on air photographs by freshness of topographic expression and a general absence of solifluction features and large-scale patterned ground. The type region for the Baffinland Drift is defined as the fiord heads between Iterbilung and Cambridge fiords; the type area is the inner reaches of Sam Ford Fiord. The youngest glaciomarine units within the Baffinland Drift are radiocarbon dated at between 5000 and 6000 BP. The moraines of Cockburn age (8000 to 9000 BP) are found within the Baffinland Drift on Baffin Island. Correlative units, such as the MacAlpine Moraine of north central Keewatin, and the moraines fringing the west coast of Melville Peninsula, were formed during a period of Laurentide ice sheet stillstand and/or readvance that had been preceded by and was followed by, periods of rapid retreat, thus contrasting with events along the northeastern perimeter of the ice sheet on Baffin Island. The use of the terms such as "Cockburn Moraines" or "Cockburn end-moraines" should be discontinued. Individual morainic ridges need to be mapped, named, and correlated, either by direct field mapping or by reference to radiocarbon dated glaciomarine facies. Kangilo Substage (5000 to 8000 BP) and Remote Lake Substage (9000 to 10,000 BP) are defined as subdivisions, along with Cockburn Substage, of the Holocene).
Bibliography of Canadian Geomorphology