1. Geography Program, University of Northern British Columbia, 3333 University Way, Prince George, B.C., Canada V2N 4Z9
2. Department of Geography, University of Illinois, Urbana, IL 61801, USA
3. Institute of Geoscience, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
4. University of Liege, Department of Physical Geography, Sart Tilman, B.11, B-4000 Liege, Belgium