Interactions between liquid water and ice at the Wright Lower glacier and Minna Saddle, McMurdo Ice Shelf

To understand the nature of interactions between liquid water and ice our investigation focussed on the Wright Lower glacier, the southern end of McMurdo Ice Shelf (Minna Saddle), the margin of the Joyce glacier in the upper Garwood Valley and on the Petrel glacier (which is located about 500m inland of middle rookery at Cape Bird). Our investigation had three main aims, 1) to understand the geometrical relationship between ice and liquid water at glacier margins, 2) to understand how debris is entrained beneath and at the margins of cold ice and 3) to understand the principle controls of the mechanical behaviour of basal ice. To meet these objectives we mapped the surface structure and morphology using aerial photographs and satellite imagery, mapped the subsurface structure using multi frequency radar (12.5, 50, 100 and 200 MHz) and examined the solute and isotope chemistry of water, ice and sediment adjacent to ice margins and from short cores extracted from the ice shelf. Radio echo sounder and GPR surveys arranged parallel and transverse to the ice flow direction were completed at the Wright Lower glacier. A 12m deep marine ice core was recovered approximately 3kms east of Minna Saddle and analyzed for its crystallography, rheology, salinity, co-isotopic composition and gas characteristics. At the Joyce Glacier a temporary climate station was installed at the ice margin to monitor melt at the glacier cliff and two temporary stream gauging stations to monitor stream flow. In addition, exposures of the moraines adjacent to the glacier edge were logged and a topographic and radar survey of the moraines and adjacent fan delta surface were conducted. A wide band of moraines up to 40m high at the margin of the Joyce Glacier were studied. Approximately 4000m of GPR data was collected in the proglacial areas of the Joyce and Garwood Glaciers. A week was spent at the Petrel Glacier undertaking a radar survey and observations of ice structures to interpret prior GPR data. 50kg of ice was sampled for analysis of ionic and isotope composition.