Australia: The Land Where Time Began

A biography of the Australian continent 

The Rolling Downs Group

The Rolling Downs Group includes the Wallumbilla Formation, that is basal Aptian, and is laterally equivalent to the Bulldog Shale, above which is the Toolebuc Formation, that is Albian marine, Allaru Mudstone, Mackunda Formation and the Winton Formation, that is predominantly of Upper Cretaceous age, that is of terrestrial origin. Mudstones, siltstones, calcareous shale and limestones, distributed widely throughout the Eromanga Basin in central and northern Queensland, make up the deposits from the Albian. The last transgressive phase of the inland sea of the Early Cretaceous is recorded by the Rolling Downs Formation, the Toolebuc Formation-Allaru Mudstone, deposited in low-energy environments, but grade upwards to the Mackunda Formation, a high-en energy shallow-water environment. Rich microfossil assemblages - plankton, spores, pollen - and mollusc assemblages - bivalves, gastropods, scaphopods and cephalopods, have been used to date the Rolling Downs Group to the upper Albian for the Toolebuc Formation-Allaru Mudstone, and for the overlying Mackunda Formation and Winton Formation, the uppermost Albion to the Cenomanian.

Sources & Further reading

1. Kear, B.P. & Hamilton-Bruce, R.J., 2011, Dinosaurs in Australia, Mesozoic life from the southern continent, CSIRO Publishing.