Re: Travesty of paleogeomagnetism

[John Denker <jsd@MONMOUTH.COM>]

At a time incorrectly stated as 10:36 PM 8/19/99 +0000, the alleged Phil P.
Johnson wrote:
> The rate of decay in the geomagnetic field sets an outside limit of
> 10,000 years for the age of the earth.

Well, let's see.  According to _Encyclopedia Britannica_, volume 17 (the
same volume that has a 49-page article on Religious Doctrines and Dogmas)
there is a discussion of the earth's magnetic field.

Among other things it says "Observations of declination made in London
since 1540, for example, show that the direction of the field at that site
has nearly completed a full cycle."  If we were to take the first-order
approximation to the most recent data (as our hero seems inclined to do) we
could use it to "prove" that the earth is only a few *hundred* years old.
It's amazing what you can do by selecting the data.

But there is other data.  My EB goes on to say "Evidence for the occurence
of magnetic reversals is unquestionable, however.  Magnetic surveys made by
ship across spreading centres in the middle of the oceans provide the best
evidence.  These data show that strips of oppositely magnetized ocean floor
appear symmetrically about such features as the Mid-Atlantic Ridge."  and
"The time between reversals is highly variable, sometimes occuring in less
than 40,000 years and at other times remaining steady for as long as
35,000,000 years."

The EB has a lot more detail on the geomagetic field -- about 13 pages, all
fairly easy to read.

Cheers --- jsd