ABSTRACT
Specific karst studies have been limited to date to the discontinuous and widespread permafrost zones in Canada. Karst landforms are developed in 180–200 m of massive Devonian limestones resting on 1000 m of dolomites. Groundwater circulation is known to pass at least 500 m down into the latter. The buttes are truly permafrozen, with no groundwater flow taking place. Fossil caves that penetrate them become completely filled with ice or frozen silt within a few meters of the entrances. A low zone is represented by poljes and the bases of all large sinkholes and solutional corridors. The karst landforms are varieties of sinkholes and solutional corridors. The rugged Nahanni karst contains many isolated, butte-like rock masses with extensive benches below them that are dotted with sinkholes. The karst is developed in Ordovician–Devonian limestones, dolomites and gypsum that dip gently westwards except where locally deformed.
