Trending Science: Introducing Zealandia, the world''s newest continent

Submerged in the southwest Pacific, the most recognisable part of the continent of Zealandia is New Zealand, but the landmass is also home to a group of isolated islands. Geographically never regarded as part of the Australian continent (even though Australia, New Zealand and the southwest Pacific islands are often grouped together under the terms ‘Australasia’ or ‘Oceania’), the paper’s authors argue that they should be classed as forming a part of an eighth, entirely new continent.

If the scientific community does agree that Zealandia should be approved as the eighth continent, (your writer was taught at school that Europe/Asia and North/South America are separate continents, thus seven current recognised continents in total, but traditions in other countries would make Zealandia only the sixth or seventh) it would be the smallest.

Zealandia covers nearly 5m square kilometres (about the size of the Indian Subcontinent or half the size of the US or Canada), of which only around 5 % is located above water. Specifically, it encompasses New Zealand, New Caledonia, Norfolk Island, the Lord Howe Island group and Elizabeth and Middleton reefs. All of these islands are populated, with the exception of the reefs.

Whilst New Zealand itself is actually 2 500 km away from its nearest neighbour Australia, Zealandia is a whole lot closer – but not joined – to the northeast Australian seaboard. Zealandia’s western point is merely a few hundred kilometres away from Queensland and is believed to have broken away from Gondwana – the immense landmass that once encompassed Australia – and sank beneath the Pacific around 60 to 85 million years ago.

The study argues that there are four criteria that need to be fulfilled before a landmass is gifted with the honour of being a continent. The first is high elevation relative to regions floored by oceanic crust; the second is a broad range of siliceous igneous, metamorphic and sedimentary rocks; then the presence of a thicker crust and lower seismic velocity; finally, well-defined limits around a large enough area to be considered a continent, rather than a micro-continent or continental fragment.

The research team states that Zealandia fulfils the first three criteria and has well-defined limits of a large land mass of 4.9 million square kilometres, therefore meriting the label of continent.

‘This is a big piece of ground we’re talking about, even if it is submerged,’ commented Nick Mortimer, a New Zealand geologist and co-author of the paper. He said that he and other researchers began to piece together the submerged continent with the release of a bathymetric map in 2002. ‘That’s when the penny dropped really… From that point, the map was literally our roadmap for some crosses, just trying to get rocks out of all of the four corners of Zealandia that we could, so we could prove up the geology.’

Whilst highly exciting for geologists, the confirmation of Zelandia’s existence as a separate continent will not impact the geopolitical balance in the region. New Zealand, for example, would not be able to make any new territorial claims as maritime borders between the nations of the region were agreed a long time ago.

But Zealandia will not be etched onto new maps of the world for some time yet. However, Mortimer is upbeat: ‘If Zealandia makes its way into popular culture and onto maps, that’s all the validation that we’ll seek.’