CGRG Bibliography of Canadian Geomorphology
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Author : Evans, D.J.A.
Date : 2007.
Title : Controlled moraines: characteristics, genesis and preservation potential.
Publication : Quaternary International
Issue : 167-168. Supplement 1 - INQUA 2007 Abstracts.
Page(s) : 111.
Abstract
Glacial geomorphologists have identified linearity in end moraine sequences in a wide variety of settings ranging from cirque basins to the former margins of ice sheets in continental interiors. This has not always been explained by marginal pushing, dumping or glacitectonic disruption but rather as the preservation of former englacial debris concentrations after complete ice melt-out. As such these landforms qualify as “controlled moraines”, where moraine form and pattern is controlled by englacial/supraglacial organization of debris concentrations. Such interpretations have significant implications for palaeoclimatic reconstructions in that glacier dynamics are inferred to be characterized by mass stagnation, even though the development of englacial structure is related to more dynamic behaviour such as englacial thrusting. Similarly, the impact of supraglacial reworking must be negligible in order to preserve moraine form. Only vertically or near vertically inclined debris concentrations may produce significant linear ridges, and as most debris-rich ice facies are manifest as up-glacier dipping folia, such linearity should be expected only in a few situations (e.g. subglacial crevasse-squeeze ridges). Assessment of the preservation potential of controlled moraine in the Quaternary landform record is accomplished through the analysis of the process-form relationships of recently deglaciated terrains in Iceland, Svalbard and Ellesmere and Baffin islands in the Canadian arctic, where glacier snouts display clear controlled moraine development and historical moraine systems have evolved from the downwasting ice. It is apparent that englacial structure may be represented in only crude form as low amplitude moraine belts that lack the intricate crenulations of marginal push moraines. Additionally, the occurrence of controlled moraine of late Pleistocene age in the permafrost of northern Canada provides a clear illustration that sharply defined linearity in controlled moraine is a supraglacial feature that may survive through large parts of interglacials as permafrost.
Bibliography of Canadian Geomorphology