Entombed Plant Communities Released by a Retreating Glacier at Central Ellesmere Island, Canada
Keywords:Ablation, Climate change, Flow, Glaciers, History, Plants (Biology), Deglaciation, Alexandra Fiord region, Nunavut, Ellesmere Island, Twin Glacier (78 50 N, 75 47 W)
The release of a dead but well-preserved high arctic plant community, entombed for about 400 radiocarbon years (WAT-778 and 789) under glacial ice at Twin Glacier, central Ellesmere Island (78°53'N, 75°55'W) is reported. Remarkably intact plants have been emerging from under the ablating front of this polar glacier which has been retreating for several decades at an average rate of 4.1 m/y over the last 22 years. The vegetation can be readily recognized as a Cassiope tetragona-Dryas integrifolia-dominated community, similar in species composition and cover to an extant Cassiope-Dryas community 200 m below the ablation front. The excellent preservation of the plants supports the thesis that polar glaciers are frozen to their bases, and hence their movements are by internal deformation rather than by erosive basal sliding.
Key words: Ellesmere Island, Twin Glacier, polar (cold) glaciers, retreating glacier, Little Ice Age, ice-buried plants, paleobotany, radiocarbon dating