This poster presents patterns of permafrost degradation under lakes with eroding shorelines in Old Crow Flats, Northern Yukon. Old Crow Flats is an arctic peatland in the continuous permafrost zone. Two shorelines with contrasting rates of recession, bank morphology, and vegetation cover were studied in the field. Depth to permafrost beneath the lakes was measured by jet drilling. Permafrost degradation occurs under very shallow water. Snow drifting on the ice surface affects patterns of permafrost degradation despite minimal effect on mean annual lake bottom temperatures. This poster was presented at the IPY 2012: From Knowledge to Action Conference, held April 22-27, 2012, in Montreal, QC, Canada. http://www.ipy2012montreal.ca/index.php Citation of conference poster: Roy-Léveillée P, Burn CR. (2012) Talik geometry and permafrost degradation under thermokarst lakes in the Old Crow Flats, Yukon Territory, Canada. IPY 2012: From Knowledge to Action, April 22-27, 2012, Montreal, QC.