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THE EUREKA SOUND LOWLANDS: AN ICE-RICH PERMAFROST LANDSCAPE IN TRANSITION
Session: Permafrost Degradation I / Dégradation du pergélisol I
Wayne Pollard, McGill University (Canada)
Melissa Ward, grad student (Canada)
Michael Becker, grad student (Canada)
The Eureka Sound area is characterized by cold polar desert conditions (MAAT of -19.7ºC), permafrost >500 m thick and a dynamic landscape where rapid change linked to melting ground ice is common. Massive ground ice and ice-rich sediments are widespread below the Holocene marine limit (150 m asl) where its distribution, content, and stratigraphic character are closely related to the nature of marine sediments. Since 1990 approximately 450 natural exposures of massive ice have been mapped, including ~100 that were studied in detail. Most are headwall exposures in retrogressive thaw slumps. These data are supplemented by 50+ core holes up to 15 m deep and GPR surveys. Over 25 years of observation the average retreat is 6.9 m/yr, but in the past 5 years the average is 7.5 m and the highest annual retreat is 23.9m. Since 2005 many new slumps have formed and ice wedges have exhibited significant thaw degradation.
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