[DoctorBeaver (OP)]

I think this is probably the best section for these questions.

We all know about continents, but what defines one? Are they merely arbitrarily delineated or is there a specific definition?

And what about Australia? Is that an island or a continent? Also, I know there is a geographical area called Australasia, is that a continent? Or Melanesia? Polynesia?

Finally, why is India (in conjunction with with Pakistan, Nepal, Bhutan, Bangladesh and a few islands) called a sub-continent when other areas of equal size aren't? We don't call West Africa a sub-continent.

[Chemistry4me]

Good question! One of the more finer ones that I've seen from you DoctorBeaver, I must say. [] I wanna know the answer too!

[DoctorBeaver (OP)]

Good question! One of the more finer ones that I've seen from you DoctorBeaver...

Are you casting aspersions on the standard of my questions?  [!]

[LeeE]

The definition is pretty arbitrary and depends on who you ask.  The simplest definition is that of a large body of contiguous land surrounded by water, in which case there'd be just four continents; America, Eurasia, Australia and Antarctica.  However, the land links that join North America to South America, and Africa to Eurasia, are so small that they are regarded by some as separate continents, raising the total from four to six.

Some people also regard Europe and Asia as separate continents, but personally, and as there is a very long land border between them, I can't see any geological reasoning for this; this division seems to be down to purely arbitrary political reasons.

[DoctorBeaver (OP)]

LeeE - it was the Europe/Asia situation that got me wondering about this question. I couldn't see any logical reason for it. And as for the Indian sub-continent, that baffles me totally.

[Bass]

From a geological perspective, a continent is a large mass of continental (light) rock- primarily granitic and gneissic.  As such, Europe is not a separate continent.  I suspect that the European Continent is more a cultural distinction than geographic.

Geologically, India is a subcontinent- since it is a separate tectonic plate from Asia.  For this reason, I would also class the Arabian peninsula as a subcontinent, and would class Africa as continent in its own right.  Where this leaves Greenland, I'm not entirely sure.

Parts of geologic continents are presently submerged- even more extensive continental areas were submerged in the past- which is why marine sedimentary rocks blanket much the land surfaces.

[DoctorBeaver (OP)]

Bass - Was it known that India is on a separate tectonic plate from the rest of Asia when it was first called a sub-continent? I know that term goes back to the early days of the British Raj.

[Bass]

No.  I suspect that India was termed a subcontinent because it was so difficult to travel to on overland routes.

[DoctorBeaver (OP)]

That sounds sensible. Thank you.

[Damo the Optics Monkey]

Some older references separate the European and Asian continents by the Ural mountains - but this is a rather weak argument.  The division as mentioned is largely cultural.

Geologically, Africa and South America fairly recently joined Eurasia and North America respectively - this could be a reason fo them to be considered separately.  (This is based on my old memory of my undergraduate days)

If tectonic plates are considered, then Japan would be an interesting case - lyig on top of he North American, Pacific, Philippines and Eurasian plates... but I know they are not considered as part of the naming.

[JimBob]

Good question! One of the more finer ones that I've seen from you DoctorBeaver, I must say. [] I wanna know the answer too!

Feeling for need to address a subject already rather adequately covered - FOG! "more finer?"  Really sir, think of the example you set for the younger persons on this forum. More Finer! Indeed Sirrah, Indeed!

[Chemistry4me]

Well, what was I meant to say? []

[Chemistry4me]

Good question! One of the more finer ones that I've seen from you DoctorBeaver...

Are you casting aspersions on the standard of my questions?  [!]

No....... Oh wait......... Of course I was!

[DoctorBeaver (OP)]

Good question! One of the more finer ones that I've seen from you DoctorBeaver...

Are you casting aspersions on the standard of my questions?  [!]

No....... Oh wait......... Of course I was!

You cheeky young pup!

[DoctorBeaver (OP)]

Geologically, Africa and South America fairly recently joined Eurasia and North America respectively - this could be a reason fo them to be considered separately.  (This is based on my old memory of my undergraduate days)

If tectonic plates are considered, then Japan would be an interesting case - lyig on top of he North American, Pacific, Philippines and Eurasian plates... but I know they are not considered as part of the naming.

As far as I am aware, the continents were identified before the science of tectonics began.

[JimBob]

So, he knows the answer but asks the question anyway?

It is so good that we have someone looking after our continuing education. I am truly grateful.