Key points are not available for this paper at this time.
Wilfried Haeberli, Lorenz King, , Surface Movement and Lichen-Cover Studies at the Active Rock Glacier near the Grubengletscher, Wallis, Swiss Alps, Arctic and Alpine Research, Vol. 11, No. 4 (Nov., 1979), pp. 421-441
Haeberli et al. (Thu,) studied this question.