We present the first quantitative attempt at reconciling the source and emplacement of granite erratics in Beacon Valley. The erratics are enigmatic because granite does not crop out in the valley and its nearest subaerial exposure is at least 10 km downstream to the east of the valley. Detailed mapping of the valley shows three types of granite erratics, which are not present in equal amounts and do not show spatial patterns. Pb isotopic and elemental compositions of the erratics eliminate the Metschel Tillite as a source and indicate they derive from the Dry Valley plutons. Our limited study tentatively ties the erratics to suites of plutons, but it does not allow a direct tie of the erratics to specific plutons because of i) the geochemical variability of the plutons and ii) the limited number of erratics that were analysed. Published data suggest the erratics provide evidence of wet-based glaciation, which covered the Dry Valleys and much of Antarctica during the mid-Miocene. Our paper also explains the problems associated with the emplacement of these erratics and the age of the massive ice in Beacon Valley.

Rock weathering plays an important role in soil development. A better understanding of how different temperature and moisture regimes impact on the rates of rock breakdown can thus contribute to our knowledge of how rates of soil production might be affected by changes in climate. Laboratory simulations using two temperature cycles determined from field data and three moisture levels were carried out on samples of granite from three locations along the Victoria Land coast. Estimates of weathering rate from these experiments were of the same order of magnitude as some other more field based studies undertaken in similar environments. However, actual values for samples from the three locations varied depending on the specific characteristics of the rock, especially grain size, porosity and extent of micro-cracking. Moisture availability was found to be an important factor in determining weight loss in the samples from Gneiss Point but not in those from Terra Nova Bay or Teall Island with the moderate level of moisture application having the greatest impact. Spring/autumn temperature cycles had a different effect on the breakdown of the rock samples compared to summer cycles but the magnitude of the effect was dependent on moisture level and rock characteristics, especially quartz content and the ability to absorb heat and moisture. The samples of rock from Terra Nova Bay and Gneiss Point where no moisture had been applied had significantly higher rates of breakdown under spring/autumn cycles than summer ones. However, this effect was reversed in the Gneiss Point samples after moisture was added. A future climate scenario using the weathering rates found in this research where there was, for example, a 10% increase in summer temperature cycles and a corresponding decrease in spring/autumn cycles predicted that a reduction in weathering would occur in conditions of little or no precipitation at Terra Nova Bay and Gneiss Point but there would be limited effect under higher levels of moisture.