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Is there a scientific definition of a continent? Is there an academic reference for such a definition? There's a tendency to correlate with tectonic plates, but of course lots of plates don't have continents.

I keep running across "by convention" and "landmass" but I don't see anything really definitive, or anything academic. I've got the whole Pangaea/Gondwana/craton/shield/continental crust/oceanic crust/plate tectonics fine, but this simple question is pretty vague.

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    $\begingroup$ From the Wikipedia article: The criterion "large" leads to arbitrary classification: Greenland, with a surface area of 2,166,086 square kilometres (836,330 sq mi) is considered the world's largest island, while Australia, at 7,617,930 square kilometres (2,941,300 sq mi) is deemed a continent. Likewise, the ideal criterion that each be a continuous landmass is contradicted by classifying North and South America as two continents; and/or Eurasia and Africa as two continents, with no natural separation by water, and the continuous land mass of Europe and Asia is considered two continents. $\endgroup$ – farrenthorpe Dec 12 '14 at 15:45
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    $\begingroup$ and... historically some geographers divided the continents by rivers (the Nile and the Don), thus considering them "islands". Others divided the continents by isthmuses, calling the continents "peninsulas". These latter geographers set the border between Europe and Asia at the isthmus between the Black Sea and the Caspian Sea, and the border between Asia and Africa at the isthmus between the Red Sea and the mouth of Lake Bardawil on the Mediterranean Sea. $\endgroup$ – farrenthorpe Dec 12 '14 at 15:47
  • $\begingroup$ No there is none although all have cratons associated with them and hence the name continental cratons. $\endgroup$ – stali Dec 12 '14 at 16:21
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According to the National Geographic Education Encyclopedia webpage about continents, defines these as the main divisions of continuous land, extending out to the edge of the continental shelf - this also includes much of the surrounding islands. In the case of the division between Europe and Asia, this division is largely due to cultural differences.

The exceptions to this are what are referred to as 'microcontinents', that National Geographic site describes as being landmasses that are 'geologically distinct' from the neighbouring continents.

There seems to not be a consensus on a tectonics based definition of a continent; however, given that continents change over time, it is suggested in the article Continents as lithological icebergs: the importance of buoyant lithospheric roots (Abbott et al. 1997) as implying that the particular lithosphere is "unsubductble' over two 0.25 billion year time periods - which, according to the authors, include mid-level and lower crustal levels, and that timeframe would also include Precambrian cratons as their core.

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