Icelandic debris flows and their relationship to Martian gullies

Conway, S. J.; Balme, M. R.; Murray, J. B.; Towner, M. C. and Kim, J. R. (2008). Icelandic debris flows and their relationship to Martian gullies. In: LPI Contributions, 1303 pp. 25–26.

URL: http://www.lpi.usra.edu/meetings/gullies2008/pdf/8...

Abstract

Martian gullies and Icelandic debris flow gullies show remarkable similarities in terms of morphology (e.g. both display the alcove – channel –debris apron structure) and in terms of scale. The aim of this project is to assess whether there is a link between their formation processes through the use of detailed morphological analysis. A debris flow, by definition, requires fluid: “Debris flows occur when masses of poorly sorted sediment, agitated and saturated with water, surge down slopes in response to gravitational attraction. Both solid and fluid forces vitally influence the motion”. In Iceland the debris flows are initiated by over-steepening and over-saturation of the regolith mantle, with the source of the water being from snowmelt or storm events. The Icelandic flows occur on regolith mantled slopes of 25-30º on the sides of fjords that are cut into basaltic bedrock: a good analogue for Martian gullies. The gullies above the town of Ísafjörður in the Westfjords region of Iceland provide a unique opportunity to study recent debris flows because the debris flow frequency is unusually high (the minimum return time between large flows is 4 years). On other slopes in Iceland debris flows are much less frequent and/or smaller because they are supply limited, so the regolith on the slopes must reach a certain thickness and steepness before it can slide. By studying very fresh debris flows the influence of post-depositional reworking is minimized.

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