During past expansions, WAIS grounded on the continental shelf of Antarctica, and a record of ice sheet fluctuations is preserved in the form of geomorphic features and sedimentary deposits. Swath bathymetry and side scan sonar data are used to image the seafloor, while seismic profiles, 3.5 kHz chirp data and cores are used to identify and map the distribution of sedimentary deposits.
Radiocarbon provides information on timing of major events.
It is now possible to map the maximum extent of grounded ice for WAIS during the last glacial-interglacial cycle. Both complete and preliminary analyses from the different study areas use mapping of subglacial landforms and deposits of deformation till to propose that WAIS advanced across the shelf to positions at or near the shelf break. Investigation into the deglacial history from this maximum position indicate that ice retreat began just before the last glacial maximum and continued through the late Holocene. Direct comparisons of the major outlets suggest that ice streams draining WAIS behaved independently of each other and that retreat of the ice sheet not only occurred in various stages, but also by different mechanisms. The bay serves an outlet for major ice streams flowing from the central portion of WAIS, yet lacks any restraining feature, such as an ice shelf at its mouth.