Sedimentation in the Great Australian Bight (GAB) has occurred in a variety of settings from the initial intra-cratonic rift to the modern carbonate shelf. An extensive palaeodrainage system, remnants of which are still preserved, supplied clastic sediments to the GAB from the north-west, north, and possibly north-east during the Mesozoic and early Tertiary. Clastic sediments were deposited in lacustrine to prograding shelf and deltaic environments. Petrological and palynological data indicate that clastic environments were predominantly humid and possible tropical to sub-tropical. High rainfall, run-off and clastic input prevented development of rift stage evaporites, and delayed establishment of a carbonate shelf until the Middle Eocene, when influence of the palaeodrainages diminished, possibly through the establishment of a less humid climatic regime. Scarcity of volcanics suggests rifting was controlled by external tectonic processes, rather than a mantle heat source. The early sedimentary evolution of the conjugate Antarctic margin up to Oligocene time may partly mirror that of the GAB.