Science

muriel_volestrangler

(101,321 posts) Fri Feb 17, 2017, 06:27 AM Feb 2017

Zealandia: Is there an eighth continent under New Zealand?

Say hello to Zealandia, a huge landmass almost entirely submerged in the southwest Pacific.

It's not a complete stranger, you might have heard of its highest mountains, the only bits showing above water: New Zealand.

Scientists say it qualifies as a continent and have now made a renewed push for it to be recognised as such.

In a paper published in the Geological Society of America's Journal, researchers explain that Zealandia measures five million sq km (1.9m sq miles) which is about two thirds of neighbouring Australia.

http://www.bbc.co.uk/news/world-asia-39000936

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.

http://www.geosociety.org/gsatoday/archive/27/3/abstract/GSATG321A.1.htm

5 replies

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Zealandia: Is there an eighth continent under New Zealand? (Original Post) muriel_volestrangler Feb 2017 OP

Does this mean that every piece of continental rock under the ocean is... NNadir Feb 2017 #1

Continents are defined as plates, not by their sea-shores. DetlefK Feb 2017 #2

So the Pacific Plate is a continent? NNadir Feb 2017 #3

elevated (though still mostly underwater), and thicker muriel_volestrangler Feb 2017 #4

I am not a geologist and am thus unqualified to declare "new" continents. This said... NNadir Feb 2017 #5

NNadir

(33,525 posts)

1. Does this mean that every piece of continental rock under the ocean is...

Reply to muriel_volestrangler (Original post)

Fri Feb 17, 2017, 07:33 AM

Feb 2017

...an island?

I'm still trying to get my head around Pluto not being a planet, and now this.

Call me an old man, which I am, but I've always assumed a continent would by definition, not be under seawater.

DetlefK

(16,423 posts)

2. Continents are defined as plates, not by their sea-shores.

Reply to NNadir (Reply #1)

Fri Feb 17, 2017, 08:22 AM

Feb 2017

For example, Eurasia and India are two different continents and where they touch each other the Himalaya formed. No sea there.

NNadir

(33,525 posts)

3. So the Pacific Plate is a continent?

Reply to DetlefK (Reply #2)

Fri Feb 17, 2017, 08:26 AM

Feb 2017

What about the Nazca plate? Continent?

Like I said, I'm still trying to get my head around Pluto not being a planet.

I don't think the Pacific Plate is a continent, but that, apparently, is just my opinion.

muriel_volestrangler

(101,321 posts)

4. elevated (though still mostly underwater), and thicker

Reply to NNadir (Reply #3)

Fri Feb 17, 2017, 08:43 AM

Feb 2017

rather than the deeper basalt-rich oceanic crust. Continental shelves are underwater, but do consist of continental crust. See eg http://www.nationalgeographic.org/encyclopedia/crust/

Looking at the diagram, most of 'Zealandia' is placed on the same plate as Australia. I wonder if that could be the objection other geologists will raise - if they're on the same plate, you might not call them separate continents.

http://www.stuff.co.nz/science/89508997/new-zealand-actually-sits-on-a-continent-called-zealandia-its-just-that-most-of-it-is-under-water

NNadir

(33,525 posts)

5. I am not a geologist and am thus unqualified to declare "new" continents. This said...

Reply to muriel_volestrangler (Reply #4)

Fri Feb 17, 2017, 09:12 AM

Feb 2017

...I did call up the original paper, which is by the way, open access, and note that all of the scientists making this claim are from New Zealand.

Maybe they're trying to elevate their nice little country to which many Americans would like to escape, even though North America is a continent and New Zealand is apparently a continent wannabe.

(I seldom use emojis, but here's one: )

I do understand the point of it not consisting primarily of basalt, being thicker, etc, but I'm still not sure I buy their claim.

This remark from the original paper...

Zealandia illustrates that the large and the obvious in natural science can be overlooked. Based on various lines of geological and geophysical evidence, particularly those accumulated in the last two decades, we argue that Zealandia is not a collection of partly submerged continental fragments but is a coherent 4.9 Mkm2 continent(Fig. 1). Currently used conventions and definitions of continental crust, continents, and microcontinents require no modification to accommodate Zealandia.

...smells of a certain amount of hubris to me.

However, this is a matter of nomenclature, which is important in science of course, but is still more of a human construct and not a statement of fact. The Geophysical Union will ultimately decide this issue of nomenclature I would guess.

I fully understand the reasoning behind the nomenclature definition of Pluto as "not a planet." However, having been a child during the dawn of the space age, I was thrilled all during the wait for New Horizons to arrive, because in my heart, Pluto was always a planet, irrespective of scientific nomenclature rulings.

I was thrilled beyond my imagination to discover that Pluto turns out to have a heart too:

?itok=23NHIO_T

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