Distribution and frequency of snow‐avalanche debris transfer in the distal part of colluvial cones in central north iceland

Abstract.

This paper emphasizes the importance of studying diffuse rock debris accumulation in the far distal part of colluvial cones with the aim of defining the spatial distribution and frequency of extreme snow avalanches. These deposits are located at some distance from the slope and have rarely been described in the literature. The field based methods used in this study confirm the snow‐avalanche origin of these deposits by (i) characterizing the distribution of the deposits along the colluvial cones and to their furthest extent, some way from the foot of the slope, and (ii) clearly defining the orientation of the long axis of the furthest and largest boulders as parallel with the main cone axis. A relative age of the deposits is obtained by assessing the vegetation cover of the boulder surfaces and by measuring the rock hardness using a Schmidt hammer. The study concludes that there were frequent extreme snow avalanches which have occurred since the Little Ice Age, and that they have decreased in magnitude during the past decade.

Key words:

• Northern Iceland
• snow‐avalanche deposits
• far distal area
• lichenometry
• Schmidt hammer