In order to obtain age estimates for the formation of two rockfall-avalanche deposits in Norangsdalen, degree of rock-surface weathering was measured using a type 'N' Schmidt hammer at six sites in Norangsdalen{Nibbedalen, Sunnmøre, Norway. By assuming a linear weathering rate, the mean Schmidt hammer rebound (R-) values obtained on the rockfall-avalanche deposits compared to mean R-values obtained on siles of 'known' age indicate that the rockfall at Skylstad may have occurred 6000 ± 700 BP, while the rockfall avalanche at Uraseter may have been deposited 4200 ± 800 BP. The indication that these rockfall events occurred in the mid-Holocene may suggest that they were initiated in connection with the deteriorating and changing climate conditions characterizing the period after the Holocene climatic optimum. This study demonstrates the potential for using the Schmidt hammer to obtain age estimates for rockfall-avalanche deposits in Norway.

A. Nesje, Department of Geography, University of Bergen, Breiviken 2, N -5035 Bergen-Sandviken, Norway;
L. H. Blikra, Geological Survey of Norway, PO Box 3006 Lade, N-7002 Trondheim, Norway;
E. Anda, Møre og Romsdal Fylkeskommune, Fylkeshuset, N-6400 Molde, Norway.