The DSIRGEO mapping programme in the 1990/91 season was designed to link the area covered in 1989/90 (Convoy Range) with that covered in 1988/89 (Thundergut Sheet). The eventual aim of the programme is to produce a revised geology of Southern Victoria Land at a scale of 1:250,000. All rock types in the area between the central Wright Valley and the Mackay Glacier, from the Miller Glacier to west ... of the Victoria Valley were mapped at 1:50,000. The resulting St Johns map sheet will also incorporate previous studies. Field work aimed to establish the extent and intrusive relationships of the various granitoid plutons known to exist in the area and relate them to the area mapping in 1988/89 season to the south. The extent and nature of the small areas of Beacon sediments was also covered. Five major rock groups were mapped including Koettlitz Group metasediments and associated orthogneisses, granitoid plutons and related dikes, Beacon Supergroup sediments, Ferrar Group dolerites and surficial glacial and fluvioglacial deposits.