Continent Europe and Asia together as a single continent, dubbed "Eurasia". In this model, the world is divided into six continents, with North America and South America considered separate continents. Geologists use the term "continent" in a different manner from geographers. In geology a continent is defined by continental crust: a platform of metamorphic and igneous rock, largely of granitic composition. Some geologists restrict the term 'continent' to portions of the crust built around stable Precambrian "shield", typically 1.5 to 3.8 billion years old, called a craton. The craton itself is an accretionary complex of ancient mobile belts (mountain belts) from
Australia (continent) meanings: travel writer Paul Theroux included New Zealand in his definition and others have used it for Australia, New Zealand and Hawaii. Another biologist, Richard Dawkins, coined the name "Australinea" in 2004. "Australia-New Guinea" has also been used. With a total land area of , the Australian continent is the smallest, and second-lowest human inhabited (after Antarctica) continent on Earth. The continental shelf connecting the islands, half of which is less than deep, covers some , including the Sahul Shelf and Bass Strait. As the country of Australia is mostly on a single landmass, and comprises most of the continent,