#Supercontinent illus?
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Doug (and Michael & Carl), thanks for the replies on the Supercontinent. That's
the first I'd heard of "Laurasia," or at least I didn't remember if I'd heard
of it before (20 years since my last college geology class–arf). The name's
just not as trippingly mnemonic as "Gondwana."
Also the first I'd heard of more than one supercontinent. You're not talking
about wholly separate continents, I take it, but good ol' Pangea cracking and
re-fusing some times before the final (current) break-up? I'm reminded of ice
on the lake breaking up and refreezing during the winter. I'm also reminded of
what's said about Columbus's "discovery" of the western hemisphere: Sure, there
might've been previous contact, but his was the historically significant one.
The current breakup is the one worth talking about. {grin} Don/Chicago (for
one more week, anyway)
Hi, Don–
Pangaea and its breakup are indeed the most interesting, since the
supercontinent cycle presumably lasts 400-500 million years; the first complex
lifeforms would have turned up after the breakup of Pangaea's predecessor
supercontinent. Hmm, maybe not so long after that a connection might not be
found – I wonder how well an increase in continental shelf areas might help
explain the Cambrian explosion of life. But figuring out that those earlier
supercontinents existed helps explain why continents are behaving as they do,
and how the earth works. If nothing else, it tells me the Atlantic will stop
widening any megayear now.
I am fuzzy about whether North America split off from Laurasia before Laurasia
was completely separated from Gondwana. I have an impression that there was
not much of continents rejoining after splitting from Pangaea (well, India was
an oddball that was moving too fast not to hit something), which is what I
would expect from supercontinent cycle theory.
–Doug