The South-East Province of South Australia is divisible into two zones, namely, the Gambier sunklands and the Padthaway "buried" horst. Tertiary overmass sediments in the sunklands attain a maximum thickness of more than 7,000ft and overlie an unknown thickness of Jurassic non-marine sandstones. Pre-Cambrian or Palaeozoic bedrock outcrops sporadically on the Padthaway horst or is covered by relatively thin veneers of Tertiary and restricted Jurassic sediments. (?) Permian glacigenes occupy infillings in the deeply sculptured Palaeozoic fossil land surface of the horst and may also occur at depth in the sunklands. A great geological hiatus occurs in the geological record of the area, but the terrestrial conditions of the Permian, Jurassic, and early Tertiary gave way in mid-Tertiary times to open-water marine conditions. During the Pleistocene epoch regional crustal warping and major eustatic oscillations of sea-level caused rapid migrations of the strand line. Volcanicity also had its influence on coastal configuration. The area is poorly mineralized and most interest has centred on oil possibilities. Past drilling has given no grounds for optimism, and it is considered significant that although many strong faults are now known to outcrop in the sunklands, none have produced authentic oil seepages. Two new formational names have been introduced in this Bulletin. They are the lower Tertiary terrestrial and paralic sediments to be known as the Knight sands and clays and the bryozoal and marly limestones described as the Gambier limestones.