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?

  • $\begingroup$ 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 Dec 1 '19 at 4:34
  • $\begingroup$ This question is on topic in my opinion $\endgroup$ – marsisalie Dec 2 '19 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 Dec 3 '19 at 7:13
  • $\begingroup$ 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). $\endgroup$ – gerrit Dec 3 '19 at 12:19

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? $\endgroup$ – Schwarz Kugelblitz Dec 2 '19 at 16:41
  • $\begingroup$ @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 Dec 2 '19 at 22:16

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? $\endgroup$ – Schwarz Kugelblitz Nov 30 '19 at 22:45
  • $\begingroup$ And the group of islands just happens to be named Australia as well? $\endgroup$ – Schwarz Kugelblitz Nov 30 '19 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 Nov 30 '19 at 22:53
  • $\begingroup$ Country or not it's still an island? $\endgroup$ – Schwarz Kugelblitz Nov 30 '19 at 22:56
  • $\begingroup$ 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 :-) $\endgroup$ – user18411 Nov 30 '19 at 23:05

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