TY - JOUR T1 - The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin JF - Climate of the Past Y1 - 2017 A1 - O'Regan, Matt A1 - Backman, Jan A1 - Barrientos, Natalia A1 - Cronin, Thomas M. A1 - Gemery, Laura A1 - Kirchner, Nina A1 - Mayer, Larry A. A1 - Nilsson, Johan A1 - Noormets, Riko A1 - Pearce, Christof A1 - Semiletov, Igor A1 - Stranne, Christian A1 - Jakobsson, Martin AB - Ice sheets extending over parts of the East Siberian continental shelf have been proposed for the last glacial period and during the larger Pleistocene glaciations. The sparse data available over this sector of the Arctic Ocean have left the timing, extent and even existence of these ice sheets largely unresolved. Here we present new geophysical mapping and sediment coring data from the East Siberian shelf and slope collected during the 2014 SWERUS-C3 expedition (SWERUS-C3: Swedish – Russian – US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions). The multibeam bathymetry and chirp sub-bottom profiles reveal a set of glacial landforms that include grounding zone formations along the outer continental shelf, seaward of which lies a  >  65 m thick sequence of glacio-genic debris flows. The glacial landforms are interpreted to lie at the seaward end of a glacial trough – the first to be reported on the East Siberian margin, here referred to as the De Long Trough because of its location due north of the De Long Islands. Stratigraphy and dating of sediment cores show that a drape of acoustically laminated sediments covering the glacial deposits is older than ∼ 50 cal kyr BP. This provides direct evidence for extensive glacial activity on the Siberian shelf that predates the Last Glacial Maximum and most likely occurred during the Saalian (Marine Isotope Stage (MIS) 6). VL - 13 UR - https://cp.copernicus.org/articles/13/1269/2017/ IS - 9 ER -