Observations on granite weathering phenomena, Mount Keinath, Northern Victoria Land, Antarctica

Rock varnish, erosional grooves, and well-developed cavernous weathering phenomena occur in close association on a small biotite-monzogranite nunatak in the Northern Foothills region, Northern Victoria Land, Antarctica. The grooves, similar in appearance to the 'rinnenkarren' described in the karst literature, are developed on steeply inclined (>35degrees) bedrock surfaces while the rock varnish occurs on adjacent, more gently sloping (<15degrees) bedrock surfaces. The varnish forms a resistant carapace through which small weathering pits have developed and below which are large cavernously weathered hollows (taffoni). We argue that the intimate association between the grooves and the rock varnish indicate the nunatak has been exposed to a long period of subaerial weathering. The preservation of both phenomena supports (a) the idea that landscape modification in this exceptionally cold and and region of Antarctica is very slow and (b) the long-term stability of the Antarctic ice sheet. Copyright (C) 2002 John Wiley Sons, Ltd.