Field of active mudboils with areas of diapiric extrusion
Location:
Victory-Townsend
Lake area, Kivalliq, Nunavut, Canada;
62° 37' N, 95° 25' W
This photo, taken from an altitude of about 50 m, shows a typical field of mudboils developed on the clay-silt-rich red till of the Victory Lake-Townsend Lake area, north of Kaminak Lake. The white spots near the centers of the mudboils are sites of active diapirism, typical examples of which are shown in ground views in images 0090 and 0216. Excavations of the areas of white-colored surface extrusions reveal red till dikes or diapirs piercing the mudboil surface (see: 0055, 0059, 0073, 0091, 0092). In the high-definition image, several linear, path-like features extend from left to right across the bottom of the photo. These are trails made by the Kaminuriak barren lands caribou herd as it passes through this area on its route to calving grounds in the vicinity of Kaminuriak Lake. The white areas of extrusion are commonly encrusted by salt efflorescences during the summer months in this semiarid area, and randomly oriented hoof prints at instrumented sites (Egginton and Shilts, 1978) suggest that the animals were grazing or licking the salt. The heavy loading of the sensitive sediment by caribou hooves may be one important factor in activating mudboils during the caribou's summer migration, which takes place when the thawed (active) layer is well developed. South of this area, I observed, from the air, plumes of suspended muddy sediment streaming from several mudboils developed on a till surface that was shallowly submerged in a lake, hours or days (the herd was not in sight) after caribou in large numbers had crossed the lake at the shallows (see also image 0205).
Updated 08/28/2009 CAB