A final site investigation has been carried out at the proposed oil refinery site at Port Stanvac, S.A. on behalf of the contractors for construction, the M.W. Kellogg Company. The test boring, involving 26 boreholes totalling 1420`0½”, and the construction of 13 test pits was carried out by Soil Engineering Laboratories, who also carried out all the laboratory testing and interpretation and compiled the engineering report. The writer was responsible for geological oversight of the work, logging of bore samples and test pits and geological mapping and interpretation. This report describes the topography of the site and deduces the tectonic development and physiographic evolution of the area. The general geology of the site was given in previous reports, but it has been amplified and is re-presented here in full. Marinoan bedrock, comprising steeply-dipping siliceous slates, sandy and silty slates, fine sandstones, quartzites and minor arkosic sandstones, outcrops abundantly on the beach, and excellent exposures of these rocks can be seen almost throughout the entire length of the coastal cliffs. The test bores and other exposures show that these rocks extend under the whole of the site, but they prove to be mainly deeply weathered and moderately soft to completely decomposed under most of the site. Only along the coastal fringe and along the eastern margin of the site are they mainly hard. The general strike is N 20° E. These rocks form part of the western limb of a tight major anticline with a shallow SSW pitch and therefore should have steep westerly dips, but observed dips range from 60°E to 85°W due to local slumping and flexures. Bedrock is truncated by a wave-out platform which is visible in the cliffs about 100 ft. above sea level. This feature rises gently inland for a distance of the order of 3000ft. Here, at the old buried coastline, bedrock rises more sharply in a series of terraces to the eastern boundary of the site. A remnant of Pliocene sandy limestone is intimately associated with this platform and a Late Pliocene sandstone, partly eroded, occurs over the terraces and tapering out on the platform. Overlying all of the foregoing rocks is a series of lenticular, piedmond-type deposits of freshwater alluvials, ranging in character from fine sands to fat clays and probably of Pleistocene age. Blanketing all of the previous deposits is a veneer of Aeolian calcareous deposits and loam, considered to be of Late Pleistocene age. The topography presents problems in sitting the process plant and ancillary units and also has some minor unfavourable features with regard to foundations. The clayey Pleistocene materials are subject to shrinking and swelling movements and present problems in foundation design. The finely sandy marl-earth is sensitive to moisture changes and presents a bearing capacity problem. The general conclusion reached is that the unfavourable aspects of this site outweigh the favourable ones, but the site is not condemned. Some features of the site have not been adequately investigated and further work is recommended.