The Physiography of the Castleguard Karst and Columbia Icefields Area, Alberta, Canada^∗

Abstract

The Columbia Icefields are highland ice caps developed upon benchlands of massive platform carbonates in the Main Ranges, Rocky Mountains. Ice is discharged via major valley glaciers, including South Glacier, Castleguard Valley. The karst is developed along the southeast edge of the central icefield, extends beneath it, and drains to springs in Castleguard Valley. Altitudinal range of the karst is 1600 to 2600 m a.s.l. Mean annual temperature is estimated to range from 0 to -7^°C over this range. Treeline is at ca. 2100 m.

All cirques and valleys were occupied by ice during the late Wisconsinan Glaciation. Modern glaciers are ca. 100 to 300 m in thickness and are receding from well-marked Neoglacial moraines. Periglacial features are prominent on high carbonate surfaces that escaped Neoglacial cover. The principal surface karst features are (1) subglacial precipitates found on newly exposed Neoglacial surfaces; (2) varieties of sinkholes seen on all exposed carbonates above 2000 m; (3) families of springs, most below 2000 m. Castleguard Cave is a major relict system.

The first interpretations of the karst, using simple morphological evidences alone, supposed that the Cave was drained by glacial entrenchment during the Wisconsinan Glaciation. Two modern groundwater caves developed beneath it.