Distribution and characteristics of rock glaciers in the southern part of Jasper National Park, Alberta

Abstract

One hundred and nineteen rock glaciers were identified in an aerial photograph inventory of 4632 km2 in Jasper National Park, Alberta. Morphological subdivision indicated 33 lobate, 76 tongue-shaped and 10 spatulate rock glaciers, whereas a 'genetic' classification identified 65 'glacial' (ice-cored) and 54 'non-glacial' (ice-cemented) rock glaciers. Head elevations of the glacial group (mean 2318 m) are significantly higher than the non-glacial group (mean 2256 m). The total elevation range of rock glaciers is 1710–2670 m.Optimal rock glacier sites are below north- or northeast-facing quartzite cliffs in cirques or on valley walls. These topographic and geologic controls produce a greater concentration of rock glaciers in the Main Ranges than the Front Ranges. Rock glacier head elevations rise eastwards and, to a lesser extent, southward across the area in response to regional climatic and latitudinal effects. Two phases of pre-'Little Ice Age' rock glacier activity are recognized on morphologic grounds and, since Little Ice Age glaciers overrode most of the evidence of Holocene glacier fluctuation, provide a major source of information on Holocene climatic fluctuations. Preliminary data suggest most rock glacier activity pre-dates the Little Ice Age and the oldest phases probably occurred between 6600 and 9000 BP.