What is a Continent?

[GrimsbyPacer]

TheEdge, interesting post. You say Greenland isn't big enough to be a continent, but you then say Zealandia is a submerged continent. The submerged continent looks to be of similar size to Greenland and much smaller than Australia.
Should Zealandia be considered as another continent? You're comment about including undersea shelves would suggest so. I also found Kerguelen in the South Indian Ocean is another submerged continent according to some.
I don't consider the Arctic as a continent, I was just saying some do, and that there's reasons why it's not totally unthinkable.
As AM9 said it wasn't proven to be floating until a submarine crossed it. And underwater features are still poorly known across the Earth, so maybe surfaces are more important in defining continents then underwater features?

 

[TheEdge]

TheEdge, interesting post. You say Greenland isn't big enough to be a continent, but you then say Zealandia is a submerged continent. The submerged continent looks to be of similar size to Greenland and much smaller than Australia.

Zealandia is about half the size of Australia and 1.5 million km2 bigger than Greenland.

Should Zealandia be considered as another continent? You're comment about including undersea shelves would suggest so. I also found Kerguelen in the South Indian Ocean is another submerged continent according to some.

Zealandia is basically considered to be a microcontinent. Its not big but it is a piece of (albeit submerged) continental crust and is separate of the main continental mass of Australasia. Kerguelen is a sort of microcontinent, its a large igneous province (LIP, unfathomably enourmous volcanic features, they really baffle the mind in their scale!) which, like Zealandia was above the surface and is continental crust, again submerged.

There is a lot of overlapping definitions here. There is some belief that the difference between a continent and a microcontinet is the presence of a craton (be it shield, platform or basement). Is a microcontinet different from a continental fragment. In cases like Kerguelen should LIPs created during a rift event be considered to be a microcontinent, fragment or simply just a LIP.

There are huge amounts of movement and change that has occurred to the crust and plate tectonics and geolgy is a fascinating subject, I love it. Its also ridiculously complex in places and the definitions are not simple. It deals with rocks that a 4 billion years old to rocks that are brand new, its trying to understand actions of rocks that seem solid but are in fact viscous.

 

[Domh245]

I thought they were just going to widen it even further?

The problem with just widening it would be that whilst you widen it, the ships would have to go all the way round the continent again. It would be like London Bridge again, only crippling global trade routes, rather than south londoner's commutes!

 

[GrimsbyPacer]

On the Panama canal subject, I remember the concrete used during the recent project was substandard and the project is costing too much. And a second canal will be built in Costa Rica by the Chinese. At least that's what the news said.