Stuart Range, South Australia

During the Late Cretaceous and Tertiary, central Australia experienced crustal compression resulting in very broad, low-amplitude folding, and the Stuart Range formed on a basement upwarp.

[2] Underlying the Stuart Range, the folded sediments include the Early Cretaceous (Aptian-Albian) Bulldog Shale, consisting of grey marine mudstones.

Where the Bulldog Shale has been exposed at the surface for long periods it has been subjected to deep chemical weathering, resulting in bleaching and the "multi-hued, picturesque colouration" found in the Arckaringa-Stuart Range landscape.

[3] The prolonged chemical weathering also dissolved silica which, transported through the regolith by the movement of groundwater, precipitated as the ambient conditions changed, forming silcrete (a type of duricrust), with the silica forming a secondary cement binding the sediment grains into sheets of hard, indurated rock, generally parallel to the land surface.

[5] In places where fluvial erosion has been more active, gullies have dissected the palaeosurface of the upland, forming a characteristic tableland topography where a continuing process of scarp retreat leaves behind mesas and buttes, which persist until their residual silcrete capping is finally lost.