Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

Glacial geomorphology has been used in Antarctica to reconstruct ice advance and retreat across the continental shelf during the Last Glacial Maximum. Analogous geomorphic assemblages are found in glaciated fjords and can be used in a similar manner to interpret the glacial history in those areas. In addition, understanding the distribution of submarine landforms in bays and the local controls exerted on ice flow can help improve ice-sheet models through these complicated drainage areas. We present multibeam swath bathymetry from several bays in the South Shetland Islands and the western Antarctic Peninsula. The submarine landforms are described and interpreted in detail. A schematic model was developed showing the features found in the bays; from flutings and moraines in the inner bay, to grounding zone wedges and drumlins in the middle bay, and streamlined features and meltwater channels in the outer bay areas. In addition, we analysed local variables in the bays and observe that: 1) bay length and width exert a control on the number of landforms found in the bays, the geometry of the bays dictates the types of features that form; 2) bays with shallower water depths tend to form geomorphic features that suggest rapid decoupling of grounded ice from the seafloor; 3) the smaller seafloor features are present only in the smaller glacial systems indicating that short-lived atmospheric and oceanographic fluctuations, responsible for the formation of these landforms, are only recorded in these smaller systems; and 4) meltwater channels are abundant on the seafloor, however some are subglacial, carved in bedrock, and some are modern erosional features, carved on soft sediment. Lastly, based on geomorphological evidence, we propose the features found in some of the inner bay areas were formed during a recent glacial advance, likely the Little Ice Age.