CGRG Bibliography of Canadian Geomorphology
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Author : Dionne, J-C.
Date : 1984
Title : Palsas and the southern limit of permafrost in the Northern Hemisphere: the case of Blanc-Sablon, Quebec. [Palses et limite méridionale du pergélisol dans l'hémisphère nord: le cas de Blanc-Sablon, Québec.]
Publication : Geographie physique et Quaternaire
Issue : 38(2):
Page(s) : 165-184
Abstract
Typical palsas occur in the area of Blanc-Sablon (51 29 N, 57 10 W), south of the southernmost limit of sporadic permafrost in Quebec as it is known today. They are found in small peat bogs located in the upper section of a broad valley filled with fine-grained Quaternary deposits. The sites are scattered in an area between 35 and 60 m a.s.l., approximately 5 km from the present shoreline of Brador Bay. Palsas, 1 to 3 m high are composed of a mineral core of stratified fine sand and silt with segregated ice and a peat cover 75 to 100 cm in thickness. The top of palsas is usually flat or rounded, and the peat cover is commonly eroded. The permafrost table was found at a depth of 30 cm, on August 20, 1979. Several thermokarst depressions occurring in the palsa bogs give evidence of a high degree of degradation of palsa complexes. The mean annual air temperature at Blanc-Sablon is 0,6 C. A review of the literature indicates that these palsas are located south of the southernmost limit of palsas in Canada and Europe. They are probably relict features formed during cooler conditions.
Bibliography of Canadian Geomorphology