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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?

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  • $\begingroup$ Australia is a country which consists of the continent of Australia, plus a number of islands (over 8000, per Wikipedia: 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 :-) $\endgroup$
    – jamesqf
    Commented Dec 1, 2019 at 4:34
  • $\begingroup$ This question is on topic in my opinion $\endgroup$
    – marsisalie
    Commented Dec 2, 2019 at 11:22
  • $\begingroup$ Following your argrument Eurasifrica would be the largest island. All three continents are connected, they are sorrounded by water... which makes them an island? $\endgroup$
    – Erik
    Commented Dec 3, 2019 at 7:13
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    $\begingroup$ Just a note: Australia is the 6th largest country, not 5th. Minor point. $\endgroup$ Commented Jan 26, 2022 at 1:14
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    $\begingroup$ 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. $\endgroup$ Commented Feb 6, 2023 at 4:29

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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.

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  • $\begingroup$ I still don't get it something is a continent as opposed to being an island just doesn't make sense? $\endgroup$ Commented Dec 2, 2019 at 16:41
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    $\begingroup$ @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. $\endgroup$
    – Ken Fabian
    Commented Dec 2, 2019 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).

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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.

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  • $\begingroup$ But like Australia is a country as well? $\endgroup$ Commented Nov 30, 2019 at 22:45
  • $\begingroup$ And the group of islands just happens to be named Australia as well? $\endgroup$ Commented Nov 30, 2019 at 22:48
  • $\begingroup$ 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 .... $\endgroup$
    – user18411
    Commented Nov 30, 2019 at 22:53
  • $\begingroup$ Country or not it's still an island? $\endgroup$ Commented Nov 30, 2019 at 22:56
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    $\begingroup$ 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). $\endgroup$ Commented Dec 1, 2019 at 17:26
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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

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  • $\begingroup$ So which of them do you say is the largest island in the world? $\endgroup$ Commented Jun 17, 2023 at 1:16
  • $\begingroup$ The one that isn't Australia ;) $\endgroup$
    – f.thorpe
    Commented Jun 17, 2023 at 3:50
  • $\begingroup$ So why don't you include it in your answer? The OP wants to know which of them is the largest. Knowing the type of island for each doesn't help without conclusion. $\endgroup$ Commented Jun 17, 2023 at 3:56
  • $\begingroup$ That's funny, I thought the question was "Is Australia the largest island". I've stated that Australia is not an island. $\endgroup$
    – f.thorpe
    Commented Jun 17, 2023 at 4:01
  • $\begingroup$ Australia is a continetal mass consisting of several islands which one of them is the largest among all. Don't you think? $\endgroup$ Commented Jun 17, 2023 at 4:04

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