CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Allard, M.; and Kasper, J.N.
Date : 1998
Title : Ice wedge activity and climate changes during the recent Holocene near Salluit, northern Québec, Canada.
Publication : American Geophysical Union.1998 Fall Meeting. December 6-10, 1998. San Francisco, California [abstract].
Issue :
Page(s) :
Abstract
Sixty-two ice-wedges were excavated under polygon sides at five different sites on the Holocene terraces of the Foucault river (Narsajuaq) in northern Québec, during the summer of 1991. Both the paleosols associated with past ice-wedge activity and the actual morphology of the ice-wedges were observed in the pits. As the the soil consists of alternating layers of organic-rich sand and sandy peat, the periods of past ice-wedge growth and collapse associated with thaw depth variations could be roughly dated by the radiocarbon dating of involuted (notably V shaped) organic horizons. Compilation of the dates indicates that periods of increased wedge growth and active layer thinning (e.g. 2800-2000 yr B.P.) alternated with periods of wedge decay and active layer deepening (e.g. 2000-500 B.P.). Ice-wedge cracking and growth were widely taking place during the Little Ice Age and were swicthed off at the onset of the warming at the beginning of the XXth Century. From 1946 to 1991, a well recorded climatic cooling took place which reactivated the ice-wedges. 94\% of the excavated wedges exhibited 2 to 30 cm wide pyramid-like upgrowth forms. The depths of the steps on these upgrowth features could even be correlated between sites several kilometers apart, clearly indicating a regional climatic response. The mean annual air temperature dropped from - 7.8 °C in 1946 to -8.9 °C in 1991, the cooling being felt principally in winter (from about -13.8 °C to -15.6 °C for the period October to May). The threshold temperatures for switching on ice wedge cracking likely lie in those ranges.
Bibliography of Canadian Geomorphology