The South East Province of South Australia is divisible into two zones, namely, the Gambier Sunk lands and the Padthaway "buried" horst. Tertiary over mass sediments in the sunk lands attain a maximum thickness of more than 7000 feet and overlie an unknown thickness of Jurassic non marine sandstones. Pre-Cambrian 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 land surface of the horst and may also occur at depth in the sunk lands. A major (Jaffa) fault zone (WNW-SSE) is thought to divide the sunk lands and horst and it joins with the NNE-SSW trending Kanawinka fault near Comaum. Another WNW-ESE trending fault (Tartwaup fault zone) passes through Beachport and near Mount Gambier and out to sea beyond Nelson. This zone is compound and its activity in the Beachport area has caused earthquakes in historic times. On the landward (up thrown) side of this fault the Tertiary sediments probably rarely exceed 2000 feet in thickness but to the south 7000 or more feet have been proven in the Nelson bore. 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 mineralised 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 sunk lands, none have produced authentic oil seepages. In view of the vast amounts of escaping artesian waters along these lines of dislocation, this feature is most unhopeful. However, the geological picture in the deeper portions of the sunk lands is still very incomplete and until more geophysical work is completed and drilling undertaken under geological supervision, the region's petroleum possibilities must be regarded as very incompletely tested. Jurassic sub-bituminous coal has been obtained in seams up to three feet thick in depth in the sunk lands area (Robe bore) and may occur more shallowly adjacent to or overlapping the Padthaway horst. Two new formational names have been introduced in the Bulletin. They are the lower Tertiary terrestrial and paralic sediments to be known as the Knight Clays and the Bryozoal end Merly Limestone described as the Gambier Limestone.