Australia, the smallest continent and one of the largest countries on Earth, lying between the Pacific and Indian oceans in the Southern Hemisphere. Australia’s capital is Canberra, located in the southeast between the larger and more important economic and cultural centres of Sydney and Melbourne.

Australia has been called “the Oldest Continent,” “the Last of Lands,” and “the Last Frontier.” Those descriptions typify the world’s fascination with Australia, but they are somewhat unsatisfactory. In simple physical terms, the age of much of the continent is certainly impressive—most of the rocks providing the foundation of Australian landforms were formed during Precambrian and Paleozoic time (some 4.6 billion to 252 million years ago)—but the ages of the cores of all the continents are approximately the same. On the other hand, whereas the landscape history of extensive areas in Europe and North America has been profoundly influenced by events and processes that occurred since late in the last Ice Age—roughly the past 25,000 years—in Australia scientists use a more extensive timescale that takes into account the great antiquity of the continent’s landscape.