Hemipelagic, sediment drift deposits have been discovered and mapped on the Antarctic Peninsula shelf in 300-500 m water depth. The drift located adjacent to Andvord Bay covers 44.5 km2 and exhibits continuous and discontinuous parallel reflections that conform to peaks and valleys in the acoustic basement as observed in deep-tow boomer and sparker seismic records. This style of drift deposit is a common feature of deep oceanic sediments, but is not normally found in continental shelf environments.

During the Quaternary, the Mac. Robertson shelf of East Antarctica was deeply eroded by glaciers and currents exposing the underlying basement, resulting in a scalped shelf.

During 2005 Geoscience Australia operated geomagnetic observatories at Kakadu and Alice Springs in the Northern Territory; Charters Towers in Queensland; Learmonth and Gnangara in Western Australia; Canberra in the Australian Capital Territory; Macquarie Island, Tasmania, in the sub-Antarctic; and Casey and Mawson in the Australian Antarctic Territory. Three geomagnetic repeat stations were also occupied in 2005. The Australian Geomagnetism Report 2005 (Volume 53) describes instrumentation and activities; absolute reference magnetometers; data distribution; and presents monthly and annual mean magnetic values, plots of hourly mean magnetic values and K indices at the magnetic observatories and repeat stations operated by Geoscience Australia during calendar year 2005.

Dense coral-sponge communities on the upper continental slope at 570 - 950 m off George V Land have been identified as a Vulnerable Marine Ecosystem in the Antarctic. The challenge is now to understand their likely distribution. Based on results from the Collaborative East Antarctic Marine Census survey of 2007/2008, we propose some hypotheses to explain their distribution. Icebergs scour to 500 m in this region and the lack of such disturbance is probably a factor allowing growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons. Two possible oceanographic mechanisms may link abundant filter feeder communities and canyon heads. The canyons in which they occur receive descending plumes of Antarctic Bottom Water formed on the George V shelf and these water masses could entrain abundant food for the benthos. Another possibility is that the canyons harbouring rich benthos are those that cut the shelf break. Such canyons are known sites of high productivity in other areas because of a number of oceanographic factors, including strong current flow and increased mixing with shelf waters, and the abrupt, complex topography. These hypotheses provide a framework for the identification of areas where there is a higher likelihood of encountering these Vulnerable Marine Ecosystems.

In 2010, a network of Marine Protected Areas (MPAs) was proposed for the East Antarctic region. This proposal was based on the best available data, which for the benthic regime consisted chiefly of seabed geomorphology and satellite bathymetry data. Case studies from the East Antarctic region indicate that depth and morphology are important factors in delineating marine benthic communities, particularly on the continental shelf. However, parameters such as sediment composition also show a strong association with the distribution and diversity of benthic assemblages. A better assessment of the nature of benthic habitats within the proposed MPA network is now possible with the incorporation of a compilation of sediment properties and higher resolution bathymetry grids across the East Antarctic region (see Figures A and B). Based on these physical properties, and in combination with the seabed morphology, we can now distinguish a range of distinct habitats, such as deep muddy basins, scoured sandy shelf banks, ruggedly eroded slope canyons and muddy deep sea plains. In this presentation, we assess the types of benthic habitats across the East Antarctic region, and then determine how well the proposed MPA network represents the diversity of habitats across this margin. The diversity of physical environments within the proposed MPAs suggests that they likely support a diverse range of benthic communities which are broadly representative of the surrounding region.

Life in icy waters: A geoscience perspective of life on the Antarctic seafloor

Dense hydrocoral-sponge communities have been identified on the upper continental slope of George V Land, East Antarctica and declared Vulnerable Marine Ecosystems. Analysis of physical and biological datasets collected during the 2007/08 CEAMARC survey identified that the richest communities are found in the heads of canyons which receive Antarctic Bottom Water formed on the George V shelf, and the canyons harbouring rich benthos are also those that cut the shelf break. This led to several hypotheses regarding their distribution and three main factors were identified. These hypotheses were tested during a recent marine science voyage in January 2011 to the same region. Initial analysis of the new data supports the hypotheses regarding the physical controls on hydrocoral-sponge community distribution.

Frank Stillwell was a member of Douglas Mawson's 1911-1914 expedition to Cape Denison, Commonwealth Bay, Antarctica. His 1912 diary is being edited for publication. The editor has asked for a text box to be included in the publication that describes aspects of the geomagnetism activities that formed part of the expedition's scientific program.

Prydz Bay and the Mac.Robertson Land Shelf exhibit many of the variations seen on Antarctic continental shelves. The Mac.Robertson Shelf is relatively narrow with rugged inner shelf topography and shalow outer banks swept by the west-flowing Antarctic Coastal Current. U-shaped valleys cut the shelf. it has thin sedimentary cover deposited and eroded by cycles of glacial advance and retreat through the Neogene and Quaternary. Modern sedimention is diatom-rich Siliceosu Muddy OOze in shelf deeps while on the banks, phytodetritus, calcareous bioclasts and terrigenous material are mixed by iceberg ploughing. Prydz Bay is a large embayment fed by the Amery Ice Shelf. it has a broad inner shelf deep and outer bank with depths ranging from 2400 m beneath the ice shelf to 100 m on the outer bank. A clockwise gyre flows through the bay. Fine mud and siliceous ooze drapes the sea floor however banks are scoured by icebergs to depths of 500 m.

The sediments deposited beneath the floating ice shelves around the Antarctic margin provide important clues regarding the nature of sub-ice shelf circulation and the imprint of ice sheet dynamics and marine incursions on the sedimentary record. Understanding the nature of sedimentary deposits beneath ice shelves is important for reconstructing the icesheet history from shelf sediments. In addition, down core records from beneath ice shelves can be used to understand the past dynamics of the ice sheet. Six sediment cores have been collected from beneath the Amery Ice Shelf in East Antarctica, at distances from the ice edge of between 100 and 300 km. The sediment cores collected beneath this ice shelf provide a record of deglaciation on the Prydz Bay shelf following the last glaciation. Diatoms and other microfossils preserved in the cores reveal the occurrence and strength of marine incursions beneath the ice shelf, and indicate the varying marine influence between regions of the sub-ice shelf environment. Variations in diatom species also reveal changes in sea ice conditions in Prydz Bay during the deglaciation. Grain size analysis indicates the varying proximity to the grounding line through the deglaciation, and the timing of ice sheet retreat across the shelf based on 14C dating of the cores. Two of the cores contain evidence of cross-bedding towards the base of the core. These cross-beds most likely reflect tidal pumping at the base of the ice shelf at a time when these sites were close to the grounding line of the Lambert Glacier.