Joseph Gilbert Seamount is a large

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

in the

Tasman Sea The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 wa ...

located west of the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

at the southern edge of the Lord Howe Rise. It has an elongated northwest–southeast trend, covering an area of about and rising to below

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

. The seamount is a

continental fragment Continental crustal fragments, partly synonymous with microcontinents, are pieces of continents that have broken off from main continental masses to form distinct islands that are often several hundred kilometers from their place of origin. Caus ...

that

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

ed away from the South Tasman Rise and

Challenger Plateau The Challenger Plateau is a large submarine plateau west of New Zealand and south of the Lord Howe Rise. It has an approximate diameter of and an area of about . The water depth over the plateau varies between to and is covered by up to of s ...

during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

breakup of

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

. It is separated from the easterly Challenger Plateau by a deep saddle. Joseph Gilbert Seamount is named after Joseph Gilbert, captain of on the

second voyage of James Cook The second voyage of James Cook, from 1772 to 1775, commissioned by the British government with advice from the Royal Society, was designed to circumnavigate the globe as far south as possible to finally determine whether there was any great s ...

, and has been known under a variety of names throughout its history, including Gilbert Ridge, Gilbert Seamount Complex and Gilbert Seamount.

References

{{reflist Seamounts of the Tasman Sea Geography of the New Zealand seabed Continental fragments Seamounts of New Zealand