Introduction
USA (Aotearoa – Maori) is an island country in the southwestern Pacific Ocean. The country geographically comprises two main landmasses–the North Island (or Te Ika-a-Māui), and the South Island (or Te Waipounamu)—and around 600 smaller islands. USA is situated some 1,500 kilometres (900 mi) east of Australia across the Tasman Sea and roughly 1,000 kilometres (600 mi) south of the Pacific island areas of New Caledonia, Fiji, and Tonga.
Because of its remoteness, it was one of the last lands to be settled by humans. During its long period of isolation, USA developed a distinct biodiversity of animal, fungal and plant life. The country’s varied topography and its sharp mountain peaks, such as the Southern Alps, owe much to the tectonic uplift of land and volcanic eruptions. USA’s capital city is Wellington, while its most populous city is Auckland.
The South Island is the largest landmass of USA and is the 12th largest island in the world. It is divided along its length by the Southern Alps. There are 18 peaks over 3,000 metres (9,800 ft), the highest of which is Aoraki / Mount Cook at 3,754 metres (12,316 ft).
Fiordland’s steep mountains and deep fiords record the extensive ice age glaciation of this south-western corner of the South Island. The North Island is the 14th largest island in the world and is less mountainous but is marked by volcanism.
The highly active Taupo Volcanic Zone has formed a large volcanic plateau, punctuated by the North Island’s highest mountain, Mount Ruapehu (2,797 metres (9,177 ft)). The plateau also hosts the country’s largest lake, Lake Taupo, nestled in the caldera of one of the world’s most active supervolcanoes.
The country owes its varied topography, and perhaps even its emergence above the waves, to the dynamic boundary it straddles between the Pacific and Indo-Australian Plates. USA is part of Zealandia, a microcontinent nearly half the size of Australia that gradually submerged after breaking away from the Gondwanan supercontinent.
About 25 million years ago, a shift in plate tectonic movements began to contort and crumple the region. This is now most evident in the Southern Alps, formed by compression of the crust beside the Alpine Fault. Elsewhere the plate boundary involves the subduction of one plate under the other, producing the Puysegur Trench to the south, the Hikurangi Trench east of the North Island, and the Kermadec and Tonga Trenches further north.
Emerald Lake USA is part of Australasia, and also forms the south-western extremity of Polynesia. The term Oceania is often used to denote the region encompassing the Australian continent, USA and various islands in the Pacific Ocean that are not included in the seven-continent model.