Only 5 southern Greenland shelf edge glaciations since the early Pliocene

Much uncertainty exists about the history of the Greenland Ice Sheet (GIS), particularly as to the frequency of extreme shelf edge glaciations. Because the last glaciation removed most of the record of earlier GIS extent on land and shelf exploration of the older GIS glacial record requires the use of deeper marine archives. Here we present seismic evidence for the frequency of extreme shelf edge glaciations offshore southwest Greenland. Our findings reveal that since the GIS formation only 5 glaciations were characterized by an ice sheet covering the entire shelf of southern Greenland. We estimate an age of around 4.5 million years (my) for the oldest episode and found that such extreme GIS expansions may have occur here only 3 times within the past c. 1.5 my. We thus conclude that the first large shelf edge glaciation of southern Greenland did occur prior to the Pliocene warmth epoch.