*AIMS

The ongoing aim of this project is to understand the origin and paleoenvironmental significance of relict ice from glaciers and lakes, which now lies buried by surficial sediments in many parts of the Dry Valleys. This phase of the project focuses on relict ice, buried in Lower Victoria Valley, which will be used as an analogue for relict ice in Beacon Valley. Of particular value will be the independent dating of sediments covering the ice using a new method of atmospherically derived beryllium-10.

Since the proposal was written, studies have shown that the use of atmospheric Be-10 to date Antarctic soil profiles gives equivocal results, and an independent test is needed. This requires sampling of a soil profile in a deposit of a known age. Unfortunately, such deposits are not available Lower Victoria Valley, but may possibly exist in Beacon Valley. Although we will have to wait until next season to sample such a deposit (Lower Wright Valley), Be-10 dating will be carried out on soils sampled in Beacon Valley and may give confirming dates.

In this field season, we sampled the modern environments and stratigraphically recent ice deposits in Lower Victoria Valley as well as the modern and buried ice deposits in Beacon Valley. The main aim will be to analyse the ice for percentages of O₂, N₂ and Ar in the occluded gas bubbles. Ratios of these gases can be used to distinguish glacial and lake ice. The gas analyses will be used in conjunction with standard chemical (6 cations and 3 anions) and stable isotopic analyses to help characterize the ice. Results from this study will not only help with interpreting the origin of the buried ice but also test Hall's (2002) lake model for Victoria Valley.

A further aim is to investigate the use of resistivity measurements for detecting massive ice and ice cemented sediment. Compared to other geophysical methods, this is a relatively simple and inexpensive method. Seismic methods will be attempted in Beacon Valley by the Marchant group (NSF program), while GPR has had limited success. Gravity measurements have been made (Sletten) but have not been processed. Thus, if resistivity methods prove to be useful, they would go a long way towards understanding the extent of buried ice in the Dry Valleys.