The PARACHILNA map area (31 to 32°S, 138 to 139.5°E) occupies the central Flinders Ranges which are made up of folded, mostly marine sedimentary Neoproterozoic and Cambrian rocks of the Adelaide Geosyncline, and adjoining plains underlain by Cainozoic sediments of the Torrens Basin and Callabonna Sub-basin. The oldest rocks in the ranges are the Callanna Group of Willouran age, consisting of sandstone, siltstone, dolomite and limestone deposited under evaporitic conditions and containing mafic volcanics and intrusives. These are variably disrupted in diapiric complexes intrusive into the overlying successions. Of the latter, the Torrensian-age Burra Group comprises sandstone, siltstone and dolomite (in part stromatolitic) with sedimentary magnesite and black chert. There are no sedimentary contacts between the Callanna and Burra Groups, but the latter is unconformably overlain by the Umberatana Group, commencing with diamictite, sandstone, siltstone and sedimentary ironstone deposited during the first (Sturtian) glaciation. Carbonaceous siltstone, sandstone and dolomite were deposited in the ensuing late Sturtian transgression. Siltstone, sandstone and limestone of the early Marinoan middle Umberatana Group are overlain by red sandstone and local diamictite deposited during the second (Marinoan) glaciation. Marinoan post-glacial sediments comprise the two major upward-shallowing cycles of the Wilpena Group. The lower commences with a distinctive thin marker dolomite. The upper cycle includes siltstone, silty limestone and sandstone, including the Pound Subgroup at the top, famous for its contained Ediacara assemblage of soft-bodied metazoan fossils. Sedimentation resumed with marine transgression in the Early Cambrian after a basin-wide break at the end of the Neoproterozoic. In the Hawker Group, worm-burrowed sandstone is succeeded by shallow-water limestone, in part with archaeocyaths and other faunas, and then deeper water limestone and shale. Redbeds and another marine limestone were deposited in the late Early Cambrian. Sparsely fossiliferous redbed and sandstone deposition of the Lake Frome Group continued into the Middle Cambrian. During the ~500 Ma Delamerian Orogeny, the Neoproterozoic-Cambrian succession was folded into broad dome and basin structures in northern and central PARACHILNA, where metamorphic grade is extremely low, and into arcuate anticlines and synclines accompanied by cleavage formation and greenschist-facies metamorphism in the southeast, where it forms part of the Nackara Arc. Post-Delamerian cover includes a small outlier of late Palaeozoic glacial sediments preserved near Blinman, and Eocene and Oligo-Miocene terrestrial sediments in the Torrens Basin on western PARACHILNA. Piedmont slope deposits of latest Tertiary to Holocene age flank the ranges, which have undergone uplift throughout the Cainozoic. Pleistocene-Holocene alluvial sediments are widespread within the ranges as well. Fossils found on PARACHILNA include Neoproterozoic stromatolites, acritarchs and the Ediacara assemblage, while Cambrian strata contain abundant trace and shelly fossils including archaeocyaths, trilobites, brachiopods and molluscs. The central Flinders Ranges contain numerous small, low-grade copper and base metal occurrences, the former mainly associated with diapirs and the latter with MVT mineralisation in Hawker Group carbonates. Micaceous haematite formed locally from alteration of Neoproterozoic limestone. Barite is the most important non-metallic resource known on PARACHILNA, and the only commodity currently under commercial production. There is potential for further exploration for base metals, diamonds, coal, evaporites, hydrocarbons and groundwater.