Thermal Contraction Cracks in an Arctic Tundra Environment
ABSTRACT. Field observations in the Mackenzie Delta area largely substantiate Lachenbruch's theoretical considerations of thermal contraction crack development. Frost crack patterns, representing the incipient stage of tundra polygons, were observed on both bare and vegetated surfaces of low al...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.498.9686 http://pubs.aina.ucalgary.ca/arctic/Arctic25-2-142.pdf |
| Summary: | ABSTRACT. Field observations in the Mackenzie Delta area largely substantiate Lachenbruch's theoretical considerations of thermal contraction crack development. Frost crack patterns, representing the incipient stage of tundra polygons, were observed on both bare and vegetated surfaces of low alluvial flats and sandspits of three islands. Individual polygons, where developed, ranged in size from 20 to 30 metres diameter on bare surfaces to 2 to 3 metres on sedge-covered areas, and 80 per cent of the angular intersections measured were of the orthogonal type. Most cracks exhibited random orientations, except in close proximity to water bodies where tendencies toward normal and subparallel orientations occurred. RBSUME. Fentes de contraction thermique dam un milieu de toundra arctique. Des observations sur le terrain, dans la rtgion du delta du Mackenzie, appuient largement les considtrations thtoriques de Lachenbruch sur le ddveloppernent des fentes de contraction thermique. Des figures de fentes de gel, reprdsentant le stade initial de polygones de toundra, ont it6 observts B la fois sur des surfaces nues et sur des surfaces recouvertes de vtgdtation, sur des alluvions et des flkches sableuses |
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