Evidence on Palaeozoic tectonism in South Australia is restricted both in time and space; most of the areas mentioned here are from the Mount Lofty – Flinders Ranges, locus of the Adelaide Geosyncline. The Indulkana area on the south-east edge of the Musgrave Block suggests a pre-Ordovician folding of the Upper Proterozoic sequence related to a fault in the crystalline basement. In the Great Artesian Basin, subsurface information shows a long history of uplift of the Gidgealpa anticline and a deformation between the Ordovician and Permian. In the central Flinders Ranges the Blinman diapir was rising in the Upper Proterozoic; sinking of a graben associated with the Oraparinna diapir ceased before Middle Cambrian time. From fossil evidence, the main Palaeozoic orogeny in this area hast have begun no earlier than Middle Cambrian. In the Mount Lofty Ranges there is stratigraphic evidence for mild tectonism in late Precambrian and early Cambrian time, as exemplified by unconformities in the Truro area and the White Point Conglomerate on Kangaroo Island. Using a K-Ar age of the Encounter Bay granite (457 x 10° years) the main orogeny in the south may be placed between Middle Cambrian and Middle Ordovician; there were at least two phases of folding. Tectonism produced varying effects such as gentler, more open folds accompanied by diapirism in the central Flinders Ranges and steeper, more crowded folds accompanied by basement folding and thrusting in the south and Olary regions. Deformation is generally more intense in anticlinal areas.