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Boundaries: Barriers that define a system

Oceania is a region made up of thousands of islands throughout the Central and South Pacific Ocean. It includes Australia, the smallest continent in terms of total land area. Most of Australia and Oceania is under the Pacific, a vast body of water that is larger than all the Earth’s continental landmasses and islands combined. The name “Oceania” justly establishes the Pacific Ocean as the defining characteristic of the continent. 

Oceania is dominated by the nation of Australia. The other two major landmasses of Oceania are the microcontinent of Zealandia, which includes the country of New Zealand, and the western half of the island of New Guinea, made up of the nation of Papua New Guinea. Oceania also includes three island regions: Melanesia, Micronesia, and Polynesia (including the U.S. state of Hawaii). 

Oceania’s physical geographyenvironment and resources, and human geography can be considered separately.

Oceania can be divided into three island groups: continental islands, high islands, and low islands. The islands in each group are formed in different ways and are made up of different materials. Continental islands have a variety of physical features, while high and low islands are fairly uniform in their physical geography.

Continental Islands

Continental islands were once attached to continents before sea level changes and tectonic activity isolated them. Tectonic activity refers to the movement and collision of different sections, or plates, of the Earth’s crust.

Australia, Zealandia, and New Guinea are continental islands. These three regions share some physical features. All three have mountain ranges or highlands—the Great Dividing Range in Australia; the North Island Volcanic Plateau and Southern Alps in New Zealand; and the New Guinea Highlands in Papua New Guinea. These highlands are fold mountains, created as tectonic plates pressed together and pushed land upward. New Zealand and Papua New Guinea also have volcanic features as a result of tectonic activity. 

Although they share some landscape features, each of these regions has distinct physical features that resulted from different environmental processes. Australia’s landscape is dominated by the Outback, a region of deserts and semi-arid land. The Outback is a result of the continent’s large inland plains, its location along the dry Tropic of Capricorn, and its proximity to cool, dry, southerly winds. New Zealand’s glaciers are a result of the islands’ high elevations and proximity to cool, moisture-bearing winds. Papua New Guinea’s highland rain forests are a result of the island’s high elevations, proximity to tropical, moisture-bearing winds, and location right below the warm Equator.