Geographical Presentation of the Pacific and Oceania

Overview of the Pacific Ocean and Oceania

The Pacific Ocean and Oceania form a little-known area. This region is often split in two on European-centric maps, with a portion of Central Pacific Oceania left unrepresented.

The Pacific Ocean represents the geographical half of the world’s seas. The historical space of Oceania juxtaposes a quasi-continent (Australia) with about ten thousand islands, most of which are small (Polynesian and Micronesian islands). Some are very large (Tasmania, New Guinea, the two New Zealand islands), others are medium-sized (the Melanesian islands), but most are small. The islands are fewer and larger in Western Oceania, and more numerous and smaller in Eastern Oceania.

It was these different areas that were initially discovered and populated by the ancestors of the Aborigines, Papuans, and other Austronesian peoples, before being rediscovered and colonized by Westerners.

Island Types in Oceania

Isolated lands are rare in Oceania (e.g., Easter Island, Nauru). Most of the small islands, grouped together in archipelagos, are the emerged parts of alignments of seamounts running from southeast to northwest.

The high islands (e.g., South Tonga, South Cook, Society, Australs, Marquesas, Hawaii) are volcanic and linked to “hot spots”. The lower islands (e.g., Tuamotu, North Cook, North Tonga, Tuvalu, Kiribati, and the Micronesian archipelagos) are atolls: coral rings that form the emergent part of volcanic islands that have slowly collapsed under their own weight and become submerged under the ocean. Coral reefs also border volcanic islands and islands of continental origin, such as the northeast coast of Australia.

The middle islands are uplifted lands resulting from tectonic forces acting along the fracture line that forms the Pacific “Ring of Fire.” This island arc is marked by volcanic phenomena, including the Solomon Islands, Vanuatu, Fiji, and Western Samoa.

The Larger Islands of Oceania

The larger islands in Oceania, such as Tasmania, New Guinea, the two New Zealand islands, and New Caledonia, which has its own volcano, are the displaced, uplifted remains of a continent from past geological periods. Another part of this landmass was formed by Australia. These islands have mountainous relief and are marked by volcanic phenomena.

Australia, in contrast, is a stable, flat quasi-continent, a detached piece of a larger whole called “Gondwana” from 120 million years ago.

Geological History and Climate of Oceania

Variations in sea levels during the Würm glaciation (70,000 BC to 10,000 BC) facilitated the settlement of New Guinea, Australia, and Tasmania (“Sahul”) by the ancestors of the Aborigines and Papuans. During this period, lower water levels brought this area together and reduced the inlets of the Wallace Line, which separated it from Southeast Asia (the “Sunda”). Around 10,000 BC, natural climate warming caused the ice to melt, resulting in a final great upwelling that isolated and divided the “Sahul” into its present-day geographical components (Papuans and Aborigines geographically separated).

This same climatic episode is considered one of the reasons for the Neolithic revolution in the Middle East and may have influenced the emergence of horticulture in New Guinea.

Climate and Ecosystems in Oceania

Australia is arid inland and temperate to the south, while New Zealand is temperate overall. On the other hand, all other islands and archipelagos of Oceania (as well as northern Australia and the far north of New Zealand) are hot and humid, with local nuances depending on latitude and relief. Precipitation is abundant, especially on the eastern coasts “to windward” of the trade winds. Low-lying islands can experience periods of drought, and cyclones are rare near the equator but seasonal and tend to strike on either side of the tropics.

Geographers distinguish between “the islands and archipelagos of intertropical Oceania” and “intertropical Oceania,” which includes the northern parts of Australia and New Zealand.

Adaptation of Island Societies

The various island societies have adapted to the geographical constraints of relief and climate. Australia, New Zealand, and New Guinea, long isolated from other continents, are home to specific flora and fauna, located east of the Wallace Line in a distinct biogeographic domain. The mountainous areas are covered in forest.