A marine survey in Prydz Bay, provides an unparalleled view of glacigenic and marine sedimentation across Prydz Channel and Amery Depression during the Late Quaternary. Gravity cores and a suite of eight radiocarbon dates indicate that the Late Wisconsin Glacial Maximum (LGM) was associated with grounding of a palaeo-ice shelf along the periphery of Prydz Channel. Deposition in front of the grounding line was dominated by ice-rafting. A granulated facies, containing angular clay and diamicton clasts, was produced by a combination of regelation freezing, near to the grounding line, and remelting of this basal debris in the sub-ice shelfsetting. Beneath these LGM marine deposits lie two key beds of diatom ooze that are distinct in size sorting and Pliocene diatoms. These "interstadial" units can be traced across most ofthe Prydz Channel, and are underlain by additional glacial marine units. Debris related to the Lambert Deep is distinct from detritus from eastern Prydz Bay and deposition ofthese two sources within the channel oscillated during the LGM. We suggest that coastal drainage systems contributed to a limited glaciation of the shelf during the LGM, rather than direct outflow via the Lambert /Amery system. It is proposed that shelf-wide glaciation is related to the duration ofglacial sea level lowstands rather than the absolute magnitude of eustatic fall during such episodes.

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Styles of glacial sedimentation and erosion in Prydz Bay respond to glacial and interglacial cycles and fall into three zones; an inner zone of net erosion, a middle zone of subglacially eroded and deformed transitional glacial marine deposits and an ourer zone of subglacial till deposition and shelf progradation. The inner zone is the region of maximum basal shear stress and inner-shelf deep formation by enhanced erosion in areas where tributary glaciers converge with the extended Lambert Glacier. The middle zone is underlain by sediments deposited near the ice-grounding zone during retreat, both as blanket••like deposits and as grounding-line moraines. This material is then deformed into elongate subglacial bedforms (megaflures or drumlins), a process that probably involves some erosion. Deforming subglacial bed conditions extend to the shelf edge within a valley crossing the shelf on the western side of Prydz Bay. The outer zone is a zone of net deposition of compact subglacial till and prograding continental slope deposits formed during full glacial conditions and glacial marine sediment formed during ice retreat. The inferred build up of ice on the Ingrid Christensen Coast may have been responsible for the development of the western ice stream that flowed in Prydz Channel. The geometry of seismic sequences in Prydz Channel suggests that this ice stream and its associated trough mouth fan developed after a major episode of shelf and slope erosion during the Pliocene.

Gravity cores taken from five sites in the Nielsen basin, a sinuous trough on the Mac. Robertson shelf of the East Antarctic continental margin, have yielded non-marine palynofloras of late Early Jurassic to Early Cretaceous age. The palynomorphs occur in glacimarine muds and are thus not in situ, but the composition of the samples indicates that no mixing of individual assemblages has occurred, and that the sediments were deposited very close to outcrop of the source of the palynomorphs. The sequence is oldest at the seaward end of the Nielsen basin, and youngest near the fault-bounded landward end. It is interpreted as reflecting pre-breakup deposition on a passive, rifted continental margin. The age of the assemblages has been established by comparison with the zonal scheme developed in the PerthBasin of Western Australia. Similarity of the Antarctic palynofloras with those known from basins on the east coast of India confirms continental reconstructions that show this part of East Antarctica to have been contiguous with eastern Indiaprior to break-up. The non-marine character of the palynomorphs suggests that marine conditions in this region of the Antarctic margin did not develop until at least late Early Cretaceous time.

Stratigraphic information concerning the retreat of the Antarctic ice sheet from the continental shelf after the Last Glacial Maximum is reviewed and compared with new results from a shelf valley off Mac. Robertson Land, East Antarctica. Radiocarbon dates and detailed lithostratigraphic logs indicate that the onset of open-marine conditions over shallow shelf banks (<200 m water depth) was achieved prior to 7000 yr BP and over deep (� 1000 m) middle to outer shelf valleys, open-marine conditions were achieved prior to 5400 yr BP. Radiocarbon dating ofbulk-organic carbon in some diatom oozes by the AMS method demonstrates problems of contamination.Jurassic pollen, spores and organic maner have been eroded and incorporated into Holocene diarom ooze, causing anomalously old 14 C dates (e. g. one surface age of7084 ± 86 yr BP was determined). This problem may arise at other locations around East Antarctica where older strata outcrop on the seafloor.