Avalanche Boulder Tongues in Lappland

Geomorphic evidence for present-day snow-avalanche and debris-flow impact in the Icelandic Westfjords

“…Most of the avalanche forms investigated are far less pronounced than those discussed in the literature (Rapp, 1959(Rapp, , 1960(Rapp, , 1995Gardner, 1970Gardner, , 1983Gardner, , 1989Luckman, 1977Luckman, , 1978Luckman, , 1992. In particular, snow avalanche impact landforms (following the terminology recommendations given by Luckman et al, 1994) are not present and none of the forms described by Corner (1980) in northern Norway were found in this study area.…”

“…In alpine terrains avalanche couloirs can be easily identified where damage to forests indicates the paths followed most frequently by the snow masses, even if other processes have also scoured the chutes (Rapp, 1959;Gardner, 1970). Although slopes in Iceland have a sparse cover of trees and shrubs (Fig.…”

Fabric Analysis: Application to Paleolithic Sites

“…In avalanches, snowmelt gives rise to a relatively disordered disposition of the rock fragments (Francou, 1988b). Rapp (1959) reported clear down slope orientations at the surface of avalanche boulder tongues in Lapland. However, on talus cones of Gaspésie (Québec), Hétu (1991) stressed that the rock debris deposited by avalanching were usually reorganized by creeping; thus, the stones are found to be orientated parallel to the slope and have an imbricated pattern.…”

Sediment Transport and Bedrock Erosion by Wet Snow Avalanches in the Guggigraben, Matter Valley, Switzerland

“…Dirty avalanches (Rapp, 1960) refer to any type of snow avalanche that has entrained soil, rock, and organic material in varying quantities during its initial motion or runout. Boulders with dimensions 350 / ARCTIC, ANTARCTIC, AND ALPINE RESEARCH ᭧ 2013 Regents of the University of Colorado 1523-0430/6 $7.00 up to meters can be entrained and transported (Rapp, 1959). The deposits thus appear characteristically brown and dirty, in contrast to clean white snow avalanches that prevail throughout much of the winter.…”

“…These studies and others (e.g. Rapp, 1959;Ward, 1985;Luckman, 1992;Keylock, 1997;Jomelli and Bertran, 2001) also highlighted characteristic avalanche-created landforms, defined the structure and geometry of dirty avalanche deposits, and discussed the origin of entrained debris and how this relates to rock wall and catchment-wide denudation. Important observations show, for example, that (a) avalanches can readily entrain loose rock fragments and large boulders from their track, which is both a mechanism of instantaneous erosion but also favors long-term denudation by continually exposing fresh rock to weathering (Rapp, 1960;Luckman, 1977); (b) avalanche debris deposits typically have no clear structure or sorting (Jomelli and Bertran, 2001), often consisting of characteristic precariously balanced boulders set down gently during snowmelt with fine sediment and organic material resting on top (Gardner, 1970); and (c) avalanches occurring beneath high mountain crests scour the rock walls below and can help carve narrow and parallel U-shaped gullies (so-called rasskars) even in massive rock at locations far above active stream channels (Allix, 1924;Matthes, 1938).…”