Earth analog for high-latitude landforms and recent flows on Mars: Icy debris fans in the Wrangell Volcanic Field, Alaska

New Mars Reconnaissance Orbiter HiRise and CRISM imagery of polar layered terrain of Mars reveals striking similarities to icy debris fans along the base of steep escarpments in Alaska formed in high-latitude periglacial environments. Process and morphologic observations of a deglaciating site in the Wrangell Mountains reveal a complex suite of supraglacial processes involved in the construction of icy debris fans. Snow, ice, and sediment are delivered to the fans from degradation of an upper-level icecap. Alaskan icy debris fans were studied during an 8-day reconnaissance mission in July 2006. We directly observed 289 major depositional events dominated by dry snow/ice avalanches, but also including icy debris flows, rockfalls, small jokulhlaups, and glacial calving. Small fans with larger catchments receive episodic icy debris flows triggered by outburst flows that mobilize rockfall sediment temporarily stored in catchments above the fan apex. Large fans with smaller catchments have better linkage to the upper icecap, providing a direct pathway for frequent large avalanches. The large, avalanche-dominated fans thicken rapidly from an overabundance of snow/ice supply to the point where they become hybrid fan-glaciers. Surficial geology evolves rapidly in this high-latitude environment through both depositional events and solar-driven albedo changes that occur daily. Ground penetrating radar surveys show that subsurface sedimentary architecture and fan evolution is similar to the active surface processes and deposits observed on the fans. Direct field observations of active geomorphic processes provide unique insights on the pace and nature of high-latitude landscape evolution during climate changes on both planets.