SUMMARY

Shallow geological, geotechnical, and environmental investigations in sub-arctic regions require a unique approach because of complex near-surface conditions. The surficial geology in these regions includes a thin layer of muskeg, silt, or sand. Bedrock can be sedimentary, metamorphic, or igneous, and is usually shallow. Permafrost is present as either a continuous o r discontinuous layer with a thin, seasonally active layer. A combination of surface and airborne geophysical surveys, supported by drilling, sampling, and borehole geophysical logging, has proven to be an effective way of characterizing the subsurface extent of the permafrost and cover. Terrain conductivity surveys showed the seasonal development of an active (unfrozen) zone of highly variable depth. Electrical resistivity surveys produced cross-sections of the subsurface down to depths of 30 m, that showed the presence of permafrost lenses and taliks (wedges of thawed overburden).

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