New term proposed for continental crust under New Zealand

Photo courtesy of Wikimedia Commons This map depicts the southern part of Zealandia, an recently-discovered continent underneath New Zealand.

Photo courtesy of Wikimedia Commons
This map depicts the southern part of Zealandia, an recently-discovered continent underneath New Zealand.

BY HALEY LUCIAN '17

The Geological Society of America recently published the findings of a New Zealand based geology team. Their findings shed light on an eighth continent underneath and surrounding New Zealand. The existence of this land mass is not a new discovery by any means; scientists have known about this hidden continental crust for decades. The article’s senior author Nick Mortimer explained that geologists have been trying to put Zealandia on the official map for more than two decades, according to the BBC. The article, entitled “Zealandia: Earth’s Hidden Continent,” is a compilation of decades of research on the topic, and concludes that the land-mass referred to as “Zealandia” should be formally designated a continent.

According to the Glossary of Geology, a continent is defined as “one of Earth’s major land masses” and it is mostly accepted that continents have the following features: “(1) high elevation relative to regions floored by oceanic crust, (2) a broad range of siliceous igneous, metamorphic, and sedimentary rocks, (3) thicker crust and lower seismic velocity structure than oceanic crustal regions and (4) well-de- fined limits around a large enough area to be considered a continent rather than a microcontinent or continental fragment.” To justify Zealandia’s designation as a continent, the GSA paper argues that the land mass meets each of these require- ments.

The New Zealand team argues that with an elevation above the surrounding ocean crust, Zealandia fulfills the first prerequisite. The team does, however, explain that one of Zealandia’s “main [differences from] other continents is that it has much wider and deeper continental shelves than is usually the case.” Next, the scientists consider the specific geology of Zealandia, explaining that, in general, continents are diverse assemblies of different rock types arranged in orogenic belts formed as a result of tectonic plate interaction. An examination of the crustal structure, they explain, reveals considerable variation in physical properties. Specifically, Zealandia has a thinner oceanic crust than the other seven continents. Results further indicate “rock samples are not from separate continental fragments or blocks now separated by oceanic crust, but are from a single continental mass,” further supporting the claim of Zealandia as a continent. The researchers also observed the limits and area within which Zealandia exists. Simply stated, Zealandia is, in the view of the New Zealand geological team, large enough to be considered a continent. It is bound by explicit geological borders and considerably larger than microcontinents such as Madagascar.

It is important to note and under- stand that no governing body exists that may officially deem Zealandia a continent. Geologist Barry Kohn, who previously worked with one of the paper’s co- authors on aspects of Zealandia, stated in an interview with the Guardian that “If Zealandia makes its way into popular culture and onto maps, that’s all the validation that we’ll seek.” Marina Hogan ’17 explains that she “[hopes] that the discovery of Zealandia will quickly become accepted in the scientific community.” Hogan also echoed the sentiments from the New Zealand team by saying that “it will be interesting to see what future advancements or discover- ies will come about from this new in- formation.” If accepted into everyday vernacular, Zealandia might very well earn its place as the world’s eighth continent.

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