During deposition of the Adelaide System (Late Precambrian) and Lower Cambrian Series, which together exceed 50 000 feet in thickness, an incompetent dolomite-siltstone sequence (Callanna Beds) formed the cores of piercement structures which were forcibly intruded into the succession and which influenced later sedimentation. More than thirty discrete diapiric structures occur along fairly well-defined trends which are regarded as a basement fault system. Surface diameters of the eroded cores of the domes vary up to several miles but the injection of carbonate-silt stone breccia has caused complication of some folds and resulted in irregular bodies with dyke like tongues. The main period of folding in the early Paleozoic has resulted in cross-sectional exposures of several diapirs. Bald cap structures and inter-digitation of conglomerates with basin sediments along the flanks of the domes indicate repeated phases of diapir movement. Adjacent diapirs show evidence of uplift at widely different times from the glacial phase of the Late Precambrian to the Early Cambrian. Boulder trains derived from the core of one diapir (Enorama) successively onlap the flank of the structure and the unconformity may be traced for several miles. The same stratigraphic units (Umberatana Group) on the opposite flank, are truncated by subsequent movements of the core. An example of a structure of irregular form is the Arkaba Diapir, which shows control over facies and thickness from the top of the Umberatana Group through the Wilpena Group to the Hawker Group (Early Cambrian). Other structures (Frome and Wirrealpa Diapirs) occur on an important hinge zone which controlled Lower Cambrian deposition. The Frome Diapir shows repeated intervals of erosion near the Adelaide System – Cambrian boundary and offers exposures of both diapiric and depositional contacts. The Wirrealpa Diapir and associated faults separate an Early Cambrian sequence to the south, comprising two formations (2000 feet in thickness) from an equivalent section to the north, of six distinct units totalling 10,000 feet in thickness. The diapir core was eroded during this interval. There is exposed a cross-section of a graben which developed during the Early Cambrian above a diapir (Oraparinna), the bounding faults of which controlled the development of an Archaeocyatha biohermal bank which intertongues with basinal facies. Diapiric structures which affected Late Precambrian and early Paleozoic deposition have been recorded 750 miles to the northwest of this province from the Amadeus Basin in central Australia. Evaporitic deposits are there reported within the Bitter Springs Limestone which occurs below the Late Precambrian glacial units.