Three were large areas of land adjacent to Australia during the Triassic, because Australia was still joined to other continental areas that were part of the ancient supercontinent Gondwana.

During the earliest Triassic there was a world-wide rise in sea-level. In western Australia, the sea extended as far south as Perth, and sand bars deposited in this former sea now produce gas and minor oil around Dongara. The sea also encroached into embayments in the northwest, resulting in a rise in the water table, thus creating a wetland in what is now the Great Sandy Desert. Swampy mudflats provided an extensive habitat for burrowing organisms.

In eastern Australia the Early Triassic sea came close to the Sydney area. Farther north there was a deep embayment in the Gympie area. Inland, wide riverine plains with lakes developed west of the ancestral eastern highlands. Sediments (redbeds) deposited on these plains were stained red from the pigment derived from eroded soils in the adjacent uplands. Some volcanic eruptions occurred on upland areas in New England, which had been submerged during the greater part of the Permian.