Earth’s surface is divided into two types of crust, continental and oceanic, and into 14 major tectonic plates. A new continent was discovered under New Zealand, mostly submerged unknown continent beneath the South Pacific has been named as Zealandia.
Zealandia is a distinct geological entity and meets all the criteria applied to Earth’s seven other continents – elevation above the surrounding area, distinctive geology, a well-defined area and a crust much thicker than that found on the ocean floor.
Zealandia measured 1.9 million square miles and is 94% underwater. It had only three major landmasses, New Zealand’s North and South Islands to the south, and New Caledonia to the north Zealandia.
A 4.9 Mkm2 region of the southwest Pacific Ocean is made up of continental crust. The region has elevated bathymetry relative to surrounding oceanic crust, diverse and silica-rich rocks, and relatively thick and low-velocity crustal structure. Its isolation from Australia and large area support its definition as a continent—Zealandia.
Zealandia was formerly part of Gondwana. Today it is 94% submerged, mainly as a result of widespread Late Cretaceous crustal thinning preceding supercontinent breakup and consequent isostatic balance.
The identification of Zealandia as a geological continent, rather than a collection of continental islands, fragments, and slices, more correctly represents the geology of this part of Earth. Zealandia provides a fresh context in which to investigate processes of continental rifting, thinning, and breakup.