THE GEOMORPHIC SIGNATURE OF PAST ICE-SHEET GROUNDING LINES IN THE MARINE RECORD (Invited Presentation)

The deglaciation of high-latitude continental shelves since the Last Glacial Maximum has revealed suites of subglacial and ice-contact landforms that have remained well-preserved beneath tens to hundreds of metres of water. Once ice has retreated, sedimentation is generally low on polar shelves during interglacials and the submarine landforms have not, therefore, been buried by subsequent sedimentation. These submarine glacial landforms provide a record of past ice-sheet form and flow, and information on the processes that have taken place beneath former ice sheets. The morphology, stratigraphy and internal acoustic chacter of grounding-zone wedges and other transverse moraine ridges yields insights into the processes taking place in such locations, which are often largely inaccessible beneath modern ice sheets. These landforms also provide evidence on the nature of ice-sheet retreat – whether by rapid collapse, episodic retreat or by the slow retreat of grounded ice. Such information can be used to test the predictive capability of ice-sheet numerical models. These marine-geophysical observations of submarine glacial landforms enhance our understanding of the form and flow of past ice masses at scales ranging from ice sheets (1000s of km in flow-line and margin length), through ice streams (100s of km long), to surge-type glaciers (10s of km long).