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Path: utzoo!linus!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!psivax!friesen
From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.origins
Subject: Re: Earth-age estimates & some replies
Message-ID: <149@psivax.UUCP>
Date: Tue, 20-Nov-84 11:57:25 EST
Article-I.D.: psivax.149
Posted: Tue Nov 20 11:57:25 1984
Date-Received: Thu, 22-Nov-84 07:23:39 EST
References: <1526@qubix.UUCP> <1154@shark.UUCP>
Reply-To: friesen@psivax.UUCP (Stanley friesen)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 43
Summary: 

In article <1154@shark.UUCP> brianp@shark.UUCP (Brian Peterson) writes:
>
>X   [On continental movement]
>X   > ...he suggested that if they were [moving persistently] then the
>X   > continents would move in a straight line across the globe i.e. not
>X   > colliding "repeatedly" but exactly once.
>X   
>X   Apparently I wasn't clear - if the continents have been moving for such
>X   long, and in such a manner that collisions have resulted, why are the
>X   continents still so far apart?
>
>The straight/persistence of movement might not have been constant
>over all eternity.  Maybe the continents bounce.  Maybe they were
>real small, going in different directions, and haven't gotten
>completely stuck together yet.
>	If (assumptions you use above), then (results predicted 6-7 lines ago).
>	However, (results predicted) is false.
>	Therefore, (assumptions used) don't quite match reality.
>Brian Peterson  {ucbvax, ihnp4, }  !tektronix!shark!brianp
>				              ^

	Brian is on the right track here,  continents are moving
persisitantly but *not* uniformly!  Why should continents move in
a straight line? - they have no momentum of thier own to keep them
moving, they are being moved *actively* by convection currents in
the deep parts of the earth - called the mantle.  Look at the best
known example of large scale convestion to see how complex this
can be. look at the wind, note the following:
	a) The horizontal component comes nowhere close to moving
in a straight line - therefore it is reasonable to suppose that
continents driven by such a mechanism would not move straight.
	b) The pattern of convection cells(called Highs and Lows)
*changes* continually - in all probability so does the convection
pattern in the mantle.

Why are the continents so far apart?  Because they have been moving
outward from a common center(Pangea) for a long time now. This common
center apparently formed by *collision* of previously seperate continents.
They did not exeactly *bounce* - the new seperation is different than
the old.  Probably the relationship of the supercontinent to the
underlying mantle changed to pull them apart.

	Stanley Friesen