Scientists Are Just Starting to Understand Earth’s Eighth Continent, Zealandia | Hacker News Reader

Scientists Are Just Starting to Understand Earth’s Eighth Continent, Zealandia

atlasobscura.com

127 pointsdskrvk44 comments

Several commenters on semantics in this thread (e.g., https://news.ycombinator.com/item?id=15473604 , https://news.ycombinator.com/item?id=15473705 , https://news.ycombinator.com/item?id=15473402 ) seem to be missing the key empirical fact: that the Earth's crust comes in two distinct types: oceanic crust (https://en.wikipedia.org/wiki/Oceanic_crust) and continental crust (https://en.wikipedia.org/wiki/Continental_crust). More specifically, the distribution of crust density (and other properties) is bimodal due to being caused by distinct formation processes. The presence/lack of ocean water on top of a location on Earth is a consequence, not cause, of the crust type. This is why the continents are clearly visible on the Earth's topographical map without water. Otherwise, you'd expect the visible shape of the continental land masses to be highly dependent on the exact waterline, which is mostly not the case.

So sure, popular media is often framed around silly terminology changes, but this does not mean that calling Zealandia a continent fails to have real empirical meaning, or detract from the fact that Zealandia is unusual in being continental crust largely covered by water. Likewise, removing Pluto from the list of planets reflected the empirical fact that Pluto is qualitatively different than the other planets, and qualitatively similar to the other dwarf planets.

> Zealandia is unusual in being continental crust largely covered by water

Fits the name, by happy coincidence?

I don't think it's a coincidence. "Zealandia" comes from "New Zealand", but was probably chosen in part because of the meaning - it's mostly covered with water. "New Zealand", in turn, comes from "Zeeland" because it's surrounded by water, and "Zeeland" (= Sea Land) is so-named because it's largely water.

Zealandia is named after New Zealand, which was named after Zeeland province in Netherlands, which is province with lots of water and islands.

This is all kind of poetic and mind blowing. Perhaps the ancient Dutch people who gave the New Zealand name knew something about Zealandia. Perhaps... aliens? Looking forward to the Discovery channel special.

I think the semantic criticism is more a criticism of the article's author misleading the reader by playing on their expectations rather than an objection about the definition that's useful to people in the field.

http://www.smbc-comics.com/comics/1496847714-soonish7%20(1)....

I think most of the semantic objections to the article's title are about it being earth's eighth continent, rather than earth's eighth continent. If you're going by the tectonic plate definition, Eurasia is one continent (there's no distinct plate boundary between them), while India, Somalia, Arabia, Madagascar, the African Great Lakes, and much of Southeast Asia are all distinct continents.

I think the criterion is "mostly contiguous region of continental crust", in which case the separation between Africa and Asia might separate them, and the separation between the Americas similarly might; according to purely topological definitions there are precisely four continents (Americas, Eurasia/Africa, Australia, Antarctica and maybe Greenland). Tectonic plates don't correspond to very much from a geographic perspective -- Baja California would become two new continents, one of which groups it with the South Island of New Zealand.

The continental distinctions as they are is pretty much geopolitics. There's no passable land route between North and South America, because the connection is through thick jungle. Similarly, pretty much nobody wants to go through the Ural mountains to go overland from Europe to Asia. Since little overland commerce or credible overland invasion routes exist between continents, they can be thought of mostly independently.

Why pass through Ural mountains when you could just pass through a bridge?

As my comment is one of the ones you call out, I'll write a few words. I'm perfectly clear on the significance of Zealandia, and I find it potentially very interesting.

That said, there is plenty of continental crust that is under water. Zealandia is a particularly large and reasonably isolated piece of submerged continental crust. To me, however, that does not make it a continent; it makes it a particularly large and reasonably isolated piece of submerged continental crust. Semantics? Yes, absolutely, that is semantics, and not terribly important, but sometimes, I get irked by semantics. :)

The same thing goes for Pluto, too, lots of astronomers don't really agree with the new "official" definitions, and it's unclear if these new definitions will hold up as additional planets/dwarf planets are discovered and observed more carefully.

Pluto isn't even the biggest plutoid. You just have affections for the dog. :)

As I've grown older, I've come to find peace in letting go of semantics. Is it a dwarf planet, or is it a planet? I'm content simply pointing at the things that I recognize and saying, "There is that thing. Whatever the kids / scientists are calling it these days. I know a lot about that thing, but perhaps not it's name."

Or as Feynman put it, Names Don't Constitute Knowledge: https://youtu.be/lFIYKmos3-s

This piece does a great job explaining the follies of trying to categorize things: http://slatestarcodex.com/2014/11/21/the-categories-were-mad...

Yes. Timeless wisdom, variations from many cultures:

* The map is not the territory.

* The finger points at the moon. One must not mistake the finger for the moon.

etc.

8 continents? I guess that's Europe, Asia, Africa, North America, South America, Australia, Antarctica, and Zealandia.

But I see:

* 1 mega-continent, i.e. Eurasia, which has sub-continents Europe and India tacked on

* 3 normal continents, i.e. Africa, North America, South America

* 3 "dwarf" continents, i.e. Australia, Antarctica, Zealandia

Not only are those 3 dwarf continents far smaller than the others, but one's covered with sand, another with ice, and the other with water.

If we're talking geology, then we might as well look at the tectonic plates [0][1].

- 14 or 15 major plates

- 38 small plates

Yet people will talk about 5-7 continents all the time.

Because people will be confused no matter which ill-defined definition is used, I'm switching to the botanical one [2] with 9. It seems to at least have some practical value.

[0] https://en.wikipedia.org/wiki/Continental_plate

[1] http://peterbird.name/publications/2003_PB2002/2003_PB2002.h...

[2] https://en.wikipedia.org/wiki/Continent#Botanical_continents

I presume a lot of those plates are ignored because they're entirely underwater.

If you leave the underwater parts out, you get a reasonable amount of continents. Sure Arabia and India would confuse people a bit, but besides them it seems to map well to what people expect.

There are actually many more "dwarf" continents (the usual name is microcontinent). The Kerguelen plateau and Madagascar are the two other large ones, as far as I know. Australia and Antarctica are much larger, and in fact microcontinents are defined as being smaller than Australia.

Zealandia is just in the news because it's the latest one to have been formally called that, possibly because it's the largest one (but not enough to be in a different category) and probably also because there's an English-speaking country on it. But it's actually not especially notable.

We if are going to get into semantics Australia is actually not mostly covered with sand. A lot of it is dry, but most of the dry parts are covered in dusty scrub and grass lands.

It seems like tectonic plates are less arbitrarily defined than continents.

https://en.wikipedia.org/wiki/List_of_tectonic_plates

Nothing like discovering a new continental shelf when an underwater mining gold rush is about to start.

All the semantic arguments here would disappear if we all simply recognized the "set of continents" for what it really is: a set-valued sheaf on some parameter space (https://xorshammer.com/2016/07/24/the-cgp-grey-topos-of-cont...).

Zealandia, while interesting in many ways, doesn't come close to meeting my definition of a continent. I wish they would stop calling it that.

Well, plate tectonics is what, a 70 year old theory, at best? In the 1950's, it wasn't generally believed that continents moved.

So, I think the definition of what is, and what is not a continent is generally... fluid at this point.

See also: definition of a planet. How can you define what a planet is, if you keep discovering new ones, that don't quite fit the old definition? Pluto was "discovered" < 100 years ago.

I remember being taught in school that there was only three kingdoms of life!

Science! It changes. And that's a good thing.

Sure, the definition of a continent is somewhat subjective and subject to change, but in my personal opinion, continents are large land masses. Zealandia fails on two counts:

a) It is much too small. b) It is underwater.

The fact that it was at one time above sea level is not particularly relevant in this discussion. Much of the Mojave desert used to be underwater. Does that mean it is currently a sea?

> in my personal opinion, continents are large land masses

The point is that your personal opinion is badly formed. Your definition of a continent is almost completely useless, which is obvious when you just look at a map. How large is "large"? Is Greenland its own continent? How do you classify Indonesia?

The new definition at least makes sense. It updates the word's meaning to reflect a more scientifically literate understanding of continent formation.

There is a new definition? Pushing Zealandia as a continent is mostly just the opinion of one group of researchers. Granted their opinion may be more valid than mine in this matter, I don't see that there is yet a general consensus that I'm fighting against.

You are right, of course, that the term is poorly defined and not very useful. It is defined mostly by convention and somewhat inconsistently. I don't believe that Greenland is generally considered to be a continent by anyone nor any of the islands in Indonesia. In my mind, even Australia is borderline, but it is generally considered to be a continent. Anyway, my point was that Zealandia is so far outside the conventional definition of a continent that it is not useful to call it that. I realize not everyone will agree with me, and I would be less annoyed if people were to refer to it as "A submerged continent" rather than "THE eighth continent."

All that said, I've spent far more words on the subject than it is worth; I really don't care as much as it probably appears. I'm really only taking issue with your assertion that my "personal opinion is badly formed."

Yeah, same, I don't really care either. What actually bothers me is the concept that your personal opinion is a sufficient justification for perpetuating the status quo, regardless of the rigor of reasoning behind the proposal for the redefinition.

I like your second comment a lot better. I agree that calling it a submerged continent is much better than just calling it a continent.

Your definition is yet undefined...

Wow, it really is a lost continent, like Mu, or Hyrule from Wind Waker.

As I keep saying, the world is a strange and pretty awesome place.

This is quite the extraordinary discovery.

So we now have 8 continents and 8 planets? Just making sure my scientific knowledge is up-to-date.

It's not clear to me that there is a rigorous definition of "continent", since different cultures enumerate them differently.

For example, in the US, North America and South America are counted separately, whereas in many cultures "America" is one continent (and, a related issue is that many people in Latin America would consider the US and Canada and NOT Mexico as part of "North America"). Also in some cultures Europe and Asia are separate, and in some they are one continent.

When this first cropped up, I asked a few geologists and not even they know what a continent is. As near as I could tell, they preferred we stop using the term.

A power of two always helps! ;-)

Anyone now for 8 days in a week? (Just kidding.)

An 8 day week would actually alleviate the pressures of modern society. Give people another day of rest. We have had enough efficiency increases that the extra day of rest wouldn't 'break the efficiency bank' so to speak. This would probably be in lieu of a basic income. I'd much rather have more time than some baseline of economic necessities but that is IMHO.

And HN strikes again:

A possible "Planet Nine" in Earth's solar system would orbit far beyond Neptune

There are actually two hypothesized planets orbiting beyond Neptune. Planet Nine is pretty well accepted as a reasonable theory in the scientific community, sufficient enough to dedicate millions of dollars worth of observing time on some of the biggest telescopes on Earth to try to look for it. Planet Nine is expected to be around 10 Earth masses and have an orbit that reaches out to several hundred times farther from the Sun than Earth (AUs). The evidence pointing to a "Planet 10" is not nearly as strong but intriguing nonetheless, it's hypothesized to be a roughly Earth mass planet (or less) orbiting only maybe 2-3x as far from the Sun as Neptune

Granted, the definition of "continent" is not rigorous, and depending on where you grew up in the world, you might have learned there are 5-7 "continents."

Here I thought it was the Island of Sealand...

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