Early Pleistocene glacier ice preserved in permafrost in the eastern Canadian Arctic

Abstract Extensive amounts of glacier ice can be buried and preserved in the permafrost for thousands to millions of years under favorable conditions. Here, we combine sedimentological, cryostratigraphic, and geochemical techniques together with radiocarbon and paleomagnetic dating to show that relict early Pleistocene glacier ice was preserved in the permafrost on Bylot Island (Nunavut). The buried glacial ice sits on top of a 2.8–2.4 Ma fossil forest deposit, and the glacio-fluvial sediments overlying the ice has normal-reversed-normal magnetic polarities, suggesting that the ice was in place since at least 0.773 Ma. As such, this represents the oldest glacier ice preserved in Arctic permafrost landscapes and the earliest evidence of a Pleistocene glaciation in the eastern Canadian Arctic. The findings highlight the resiliency of ice-rich permafrost to degradation; however, the ongoing climate warming and/or recent geomorphic disturbances have now exposed the early Pleistocene age buried glacial ice to melting.