Crag-and-tail features on the Amundsen Sea continental shelf, West Antarctica

Abstract

On parts of glaciated continental margins, especially the inner shelves around Antarctica, grounded ice has removed pre-existing sedimentary cover, leaving subglacial bedforms on eroded substrates (Anderson et al. 2001; Wellner et al. 2001). While the dominant subglacial bedforms often follow a distinct, relatively uniform pattern that can be related to overall trends in palaeo-ice flow and substrate geology (Wellner et al. 2006), others are more randomly distributed and may reflect local substrate variations. Here we describe and discuss examples of large, isolated crag-and-tail features that are recognized on the Amundsen Sea continental shelf. The trough in front of Getz Ice Shelf which was generated by palaeo-ice streams, is floored by exposed bedrock (Nitsche et al. 2007; Larter et al. 2009). Geomorphological features preserved at the seabed include bedrock channels, grooves and drumlin-shaped landforms (Fig. 1a). In between these features are prominent, shallower mounds (white arrows in Fig. 1a) that …