From north to south, the sedimentary basins of Western Australia change from broad platforms of wholly marine strata that span the entire Phanerozoic (Bonaparte Gulf and Canning Basins) through the intermediate Carnarvon Basin to rifts of nonmarine Permian and Mesozoic strata (Perth Basin). These contrasts in age, facies, and structure reflect different positions of the basins in Gondwanaland: the Bonaparte Gulf and Canning Basins have lain at the continental margin facing an open ocean during the entire Phanerozoic, whereas the Perth Basin lay in the interior of Gondwanaland until India and Australia moved apart in the Cretaceous. The Eucla Basin came about by events connected with the dispersal of Antarctica and Australia in the Eocene. The northwest part of the Australian Block (Timor and the Timor Sea) was deformed in the Miocene when Australia collided with southeast Asia. Copyright.