1 Popular Summary of Scientific Work Achieved

A model to explain the occurrence of ground ice in glacial sediments and bedrock at high altitudes (>1000m) throughout the Dry Valleys where liquid water is rare was developed from work on Table Mtn. (Dickinson and Grapes 1997; Dickinson and Rosen 2003). The model is based on mineralogical, chemical and isotopic analyses of ground ice and frozen sediments that come from cores of Sirius Group sediments at Table Mtn. It indicates that the ground ice and diagenetic minerals accumulated over long periods of time from atmospheric water vapour and brine films formed on the surface of the ground. Although this model may apply at Table Mtn. for the very old glacial sediments of the Sirius Group, it has yet to be tested at other locations in the Dry Valleys.

Sugden et al. (1995) reported occurrence of massive ground ice believed to be at least 8 Ma old from Beacon Valley but this age was obtained by indirect dating of presumed in situ volcanic ash. Ice similar to that of the Beacon Valley was discovered in Pearse Valley during field season 2001/02. Pearse Valley ice originates from either the Taylor or local Schlatter glacier, but the main objective of this project is to establish whether it has the potential to yield palaeoclimatic data. In the 2002/03 season, massive ice was also found in Victoria Valley. Some of this ice was left behind by the retreat of the Lower Victoria glacier but other occurrences appear to have fed from the subsurface by ground water.

The field programme of the 2002/03 season aims to obtain representative cores and samples of this ice for isotopic dating and chemical analysis. Evaluation of analytical results may lead to deep core drilling of some of the sites to clarify further the glacial history of Pearse and Victoria Valleys