Abstract

Sand–water flows were observed on the slopes of cold-climate eolian dunes in southwestern Saskatchewan, Canada, during episodes of intense thawing in the winters of 2004 and 2005. Meltwater produced flows with varying grain–water contents on slopes of active blowout hollows and parabolic dunes. The sand–water flows emplaced small, structureless, lobate- and tongue-shaped deposits and alluvial fans. The greatest concentration of deposits occurred on south-facing slopes, which frequently thaw in winter from intense insolation. Transport modes ranged from high-density, viscous slurry flows to lowdensity, hyperconcentrated flows. The triggering cause of these flows is high pore-water pressure that develops in thawed nearsurface sand due to impeded infiltration by frozen sand with pore ice at depth. These observations broaden the environmental context of sand–water flows on dunes and contribute to interpretations of these deposits in the eolian rock record and to recent alluvial features observed on Martian sand dunes.