ALPINE KARST IN THE ROCKY MOUNTAINS OF ALBERTA AND BRITISH COLUMBIA, CANADA: AN OVERVIEW

The full range of alpine karst landforms, caves and groundwater systems can be found in major carbonate formations of Paleozoic age in the Canadian Rockies. Development generally is not as extensive as in the well-known Alps and Pyrenees, however, due to steep stratal dips in the ‘Front’ ranges and extensive cover by clastic formations in the more massive ‘Main’ ranges. The extent and depth of glacier ice was also much greater (the ‘Cordilleran Icesheet’), further restricting karstification. Principal Front range studies have focused on Crow’s Nest Pass where relicts of phreatic caves can be found up to summit levels and the Continental Divide itself is breached by modern groundwater flow, and the Maligne River basin (Jasper National Park) with the largest sinking river in Canada. The Mt Castleguard karst (Banff N.P.) is the most investigated in the Main ranges because it extends under the Columbia Icefield (greatest glacier remaining in the Rockies), contains the longest explored cave and has very dynamic but inaccessible sub-glacial karst flow: Snaring River and Small River further north are also important sites for both relict and modern process karst studies.

Eight different relationships between karst landforms and the multiple glaciations can be defined and illustrated in the Canadian Rockies, from entirely pre-glacial to exclusively postglacial in origin. Most larger forms are karst adaptations of glacial features or vice versa, including glacial cirques now drained underground to karst springs and karst depressions adapted to host small glaciers. Published process studies have covered the gamut from sub-glacial calcite precipitation to long-term solute load analyses of the trunk river basins. Some of the pioneer U series dating and stable isotope measurements of speleothems were in Castleguard Cave and at Crow’s Nest Pass, including the first example of a magnetically reversed (>780 ky) calcite from a relict spring cave 90 m above modern base level. In the near future Pb:U dating of speleothems from highest relict caves will place firm minimum ages on the relief of the modern Rocky Mountains.

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