Abstract Australian regolith materials are described, many of which are complex. Much Australian regolith dates back to the Tertiary, Mesozoic or earlier. There is a progressive change in the nature of alluvium through the Tertiary. Aridity, revealed through sand dunes and evaporites, is confined to the Quaternary. Ferricretes and silcretes are formed on lower slopes, often followed by inversion of relief. Tectonic isolation of Australia as well as climatic change is responsible for the change in the nature of terrestrial sediments since the Cretaceous.