Glacial Debris

Englacial debris was again sampled from overturned bergs about the southern grounding line of the Mackay Glacier. Two valves of a scallop were found 10 cm within the ice, on its basal surface, implying some "freezing on" occurs, at least at the edge of the tongue where the southern ice stream meets the ocean. Previously, it had been considered that the Mackay was wet based over its entire bottom and actively melted dropping basal debris immediately it entered Granite Harbour.

Samples of clasts were taken for provenance determinations. However, ice samples taken in order to determine sediment/ice ratios melted in transit to New Zealand. Measurements of sediment charged ice collected in 1983-84 show the sediment to be approximately 7.5% by weight of the basal ice. This is considered a minimum sediment concentration of the basal ice of the Mackay Glacier.