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I had participated in a quiz recently and one of the questions was 'which is the largest island in the world?'. I wrote Australia as the answer remembering that it was the 5th largest country in the world and none of the top 4 were islands.

However (and rather dreadfully) the answer given was Greenland.I took this up with the committee providing the solutions, but they simply said that Australia isn't an island and is a continental mass?

I googled it and found the same argument online which seemed to confirm that Greenland was the largest island.

But Australia is a country and the collection of islands which is a continent (more accurately described as Oceania ) is sometimes called Australia. Neither of these names would still change the fact that Australia (the country) being an island is the largest island in the world! Can someone please clarify this for me?

Schwarz Kugelblitz
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  • Australia is a country which consists of the continent of Australia, plus a number of islands (over 8000, per Wikipedia: https://en.wikipedia.org/wiki/List_of_islands_of_Australia ) Tasmania is the largest of these. Some of those are part of the Australian continent, others aren't. Politics being politics, it's certainly conceivable that Australia the country could fragment into several countries, or merge with/be conquered by some other country within a human lifetime. Not really plausible for the continent to do so :-) – jamesqf Dec 01 '19 at 04:34
  • This question is on topic in my opinion – marsisalie Dec 02 '19 at 11:22
  • Following your argrument Eurasifrica would be the largest island. All three continents are connected, they are sorrounded by water... which makes them an island? – Erik Dec 03 '19 at 07:13
  • Another point one could argue about: do you count the ice sheet or the bedrock? Apparently, Greenland would remain a single island, and probably remain the world's largest if measuring the above-sea-level bedrock (or quickly become so again due to isostatic rebound). – gerrit Dec 03 '19 at 12:19
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    Just a note: Australia is the 6th largest country, not 5th. Minor point. – JeopardyTempest Jan 26 '22 at 01:14
  • Sounds to me as if we are splitting hairs over names. Whether Australia is an "island" is as important to studying it as whether Pluto is a "planet" is to studying that orb. – Oscar Lanzi Feb 04 '23 at 01:10
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    An island is a piece of sub-continental land completely surrounded by water. That is why Australia is not an island as it is a continent. – David García Bodego Feb 06 '23 at 04:29
  • You've all missed the point. If you define an island as a continuous piece of land surrounded by water, then Europe-Asia is the biggest island, not Australia. the Americas are also bigger than Australia. However that is also the definition of a landmass, of which Australia is one. So if you exclude Europe-Asia and the Americas on that basis, then you have to exclude Australia too. The question was not what is the largest island country, but what is the largest island. Totally different question. – Angela WDP Feb 03 '23 at 13:04
  • @jamesqf Even if it was consisted of 1,000,000 islands, the largest of them which is over 7 million km$^2$ in area should be called the largest island of the world. I can't understand the reasoning of people who say Greenland is the largest in the world! Even if we compare the area of all the islands that consist Australia with all the islands that consist Greenland, again Australia wins. – Snack Exchange Jun 17 '23 at 01:11
  • I would argue Afro-Eurasia is the largest island. – John Jun 26 '23 at 16:01

4 Answers4

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Australia does get widely referred to as an island as well as as a continent - an island-continent sometimes. My understanding is that "continent" in terms of geology refers to the largest land mass of a continental plate and is more a matter of convention - a general agreement - than precise definition. Such definitions have been subject to revision.

This definition would have come after continental plates and plate tectonics were confirmed and widely accepted; proposed first by Alfred Wegener in 1912, acceptance did not come until the 1950's and 60's. Naming Australia an island predated this definition and still persists in popular usage but using the current definition it is a continent.

Greenland, being a part of the North American Plate but not it's largest landmass, gets defined as an island and is now considered the world's largest island.

Ken Fabian
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  • I still don't get it something is a continent as opposed to being an island just doesn't make sense? – Schwarz Kugelblitz Dec 02 '19 at 16:41
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    @SchwarzKugelblitz - It looks like an Etymology issue, rather than Geology, ie the study of words. Geology, like other sciences, seeks to clearly define the terminology they use, but these terms existed before the clear definitions; a continent was really big and Islands weren't. Which was which was a matter of agreement, or, for Australia, disagreement. If an island were simply land surrounded by water then Africa, Europe and Asia would be 1 island, the largest, then 2 islands after the Suez Canal opened. I suppose Geological Societies decided on the current definition. – Ken Fabian Dec 02 '19 at 22:16
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Assuming an island is defined as a body of land surrounded by water, then the largest island in the world is the Europe and Asia land mass (with Africa included if the Suez canal is not regarded as a body of water because it is man made).

Fred
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Ross Fitzgerald
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Australia can be seen as a very "continenty" continent. It contains very old stable continental lithosphere in cratons, like for instance the Pilbara or the Yilgarn craton.

I fear, the quiz makers were correct with classifying Australia as a continent.

  • But like Australia is a country as well? – Schwarz Kugelblitz Nov 30 '19 at 22:45
  • And the group of islands just happens to be named Australia as well? – Schwarz Kugelblitz Nov 30 '19 at 22:48
  • Yeah, well, a "country" is a political concept, or not ? Difficult to discuss without getting political :-) There is a convention about what's a continent and what's an island, and that tells us Greenland is an island. And not for sale, it is rumoured .... –  Nov 30 '19 at 22:53
  • Country or not it's still an island? – Schwarz Kugelblitz Nov 30 '19 at 22:56
  • Nope. And what about Antarctica ? South America ? The latter just happens to be connected to the north right now and only since recently because plate tectonics. But convention has it that even if we name the Americas distinctively they are continents. Just as Australia, which really is a continenty continent, even if girdled round by the emrald sea :-) –  Nov 30 '19 at 23:05
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    If this is a sufficient condition, then Greenland is also a continent: part of it pertains to the Laurentia craton and contains very old crustal rocks (at Isua for instance). – Jean-Marie Prival Dec 01 '19 at 17:26
  • And Madagascar. Who votes for Madagascar ? Seriously, i think the case of Australia is quite clear, at least in the literature. –  Dec 01 '19 at 18:03
  • Australians on their ... landmass: https://www.ga.gov.au/scientific-topics/national-location-information/dimensions/continental-extremities Maybe we can say that being a continent does not necessarily exclude being an island ? –  Dec 01 '19 at 18:47
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National Geographic has a nice webpage, that explains:

There are six major kinds of islands: continental (1), tidal (2), barrier (3), oceanic (4), coral (5), and artificial (6).

The article continues that when Pangaea broke up, "some large chunks of land split. These fragments of land became islands. Greenland and Madagascar are these type of continental islands."

Referring to an image (below) of Pangaea (source: Amante, C. and Eakins, B. W. 2009), it is clear that Australia is it's own continental mass, while Greenland is a piece of a larger mass. Despite Australia historically being referred to as an island country "because of its lack of land borders", it is not an island. There is a nice Wikipedia article that explains:

Europeans discovered Australia in 1606, but for some time it was taken as part of Asia. By the late 18th century, some geographers considered it a continent in its own right, making it the sixth (or fifth for those still taking America as a single continent). In 1813, Samuel Butler wrote of Australia as "New Holland, an immense island, which some geographers dignify with the appellation of another continent" and the Oxford English Dictionary was just as equivocal some decades later. It was in the 1950s that the concept of Oceania as a "great division" of the world was replaced by the concept of Australia as a continent.

It's also important to consider that sea level has a major role in how much continental mass is "island". If you consider land bridges like the Thule Bridge, one could postulate that Greenland has not always been an "island".

enter image description here

f.thorpe
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