QUOTE (tedstryk @ Aug 25 2006, 10:55 AM)
Every other continent has an associated plate, with a few minor ones attached at times...Europe and Asia share one.
The division between Europe and Asia has no geological sigificance, while the division between India and the rest of Asia does...
1) The Caribbean plate contains a large chunk of Central America. Arabia has a plate all of it own. (So does India.) If North America and South America are entitled to be classed as separate continents because they each have their own plate why not those other chunks?
If "the division between India and the rest of Asia" is of "geological significance" why not the divisions between other plates, such as the one between Arabia & the rest of Asia and between the chunk of Central America on the Caribbean plate and the rest of the Americas?
Or is the "geological significance" in India's case those impressively tall mountain its ramming into Asia has managed to push up? If so, what is the "geological significance" of the boundary between the continents of North America and South America?
2) Which raises the related issue of where do you divide North America from South America: at the northern boundary of the South America plate or at the northern boundary of the Caribbean plate? That is, if that chuck of that chunk of Central America on the Caribbean plate is not a separate continent is it part of the continent of South America or part of North America?
3) Then there's the fact that the North American plate includes Greenland and part of eastern Siberia. Does that mean those are part of the North American continent as well (just as Europe, being part of the same plate shared by most of Asia, means that Europe and Asia are part of the same continent under your scenario)?
True, there's all that water in the Bering Strait. However, during the last ice when sea levels were much lower than they are today North America was connected with that chunk of east Asia which is part of the North American plate (just as Tasmania and New Guinea were connected with Australia--although not Australia with Asia--and the British Isles with Europe).
Does that historical connection between East Asia and North America increase the likelihood of that chunk of east Asia making it into part of the continent of North America under your model or does all the water now in the Bering Strait still get in the way?
The point here what kind of boundary marker predominates in your model when deciding where the divisions between continents lie? Geographical ones like water or geological ones like tectonic plate boundaries?
A case in point: you are argue that the "division between Europe and Asia has no geological sigificance". As it happens that division traditionally runs along geographical boundaries such as the Ural Mountains and the Black Sea. If the Black Sea has "no geological significance" as a boundary between Europe and Asia what pray tell is the geological significance of the Bering Strait between Asia and North America?
The reality is that the concept of "continent" was around long before plate tectonics came into vogue. So was the division of Afro-Eurasia into three continents and the American continent into two. Boundaries of "geological significance" have little to do with defining them. Geography and history were used to decide those divisions, not geology.
A continent was and still is basically a large landmass surrounded by water, but with historical considerations tempering the division. (For more, see this Wikipedia page
It seems to me you're using plate tectonics in a novel way to try to retroactively justify elements of the historical divisions more than elements of the geographical ones, but in what seems to me to be a potentially inconsistent fashion.