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Subject: Re: Annual Increase of Variation
From: Brian Whatcott (inet@XXX.XXX)
Date: Wed Feb 13 2002 - 18:42:57 EST
At 01:36 PM 2/13/02, you wrote:
>Brian-
> <The fitting equation shows that by AD 2985, the field strength will have
>gone to zero (if everything proceeds according to its current decay rate -
>but it won't!)>
>
> Unless geology has changed theories again...I was taught that the
> magnetic field HAS and will in fact go to zero and reverse, that there is
> physical evidence in the rocks all over the planet that this is in fact
> the normal cycle for our dear planet. I don't know about the dates and
> timeline, just that over the ages the field does weaken and reverse on a
> regular basis.
There are scientists who have made a handsome living by writing books and
articles concerning "saltatory evolution" and such like still, it is
usually wise to suppose that things will carry on in much the same way that
they have been carrying on. We have a name for people who run around
crying, "The sky is falling..."
The other, more conservative approach is called gradualism.
In the matter of the plate theory of continental drift, it was a powerful
piece of evidence that a record of geomagnetic field reversals was found
on drillings sailed perpendicular to submarine sites marking plate edges.
Some materials I have been looking at, suggest a variable magnetic reversal
cycle varying between 4 megayears and 1.2 megayears depending on the
geological epoch.
On the face of it - suggesting that a reversal will happen in the next
thousand years is a bet that's about 1000: 2,000,000 against or 1:2000 so
the odds are not a betting man's delight.
Still, the evidence such as it is, does not deny the possibility.
I hear that the loss of a magnetic field, even temporarily would not be a
very healthy environment. It's not one of those dinosaur wasting impact
events - but still there are things that a magnetosphere nicely deflects.
On balance though, I guess we are more likely to get a new glaciation
before a field reversal - and that could spoil your whole day. The cycle is
only in the thousands of years, apparently.
Brian Whatcott
Altus OK Eureka!
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