Re: Pole Shifts vs Ice Ages (Revisited)
Bill Nelson wrote:
> In sci.astro Nancy Lieder <zetatalk@zetatalk.com> wrote:
>> In Article <3BBFA0D5.98840605@pushnopull.net> Pushenipol wrote:
>>> Does a compass show such thing ?
>>
>> Yes. Molten lava records the magnetic orientation of the
>> core at the time, and once hardened retains that. Thus,
>> there is some dramatic evidence of times when the crust
>> moved rapidly during pole shifts. Steens Mountain is one.
>
> Nothing you quoted, which I am not going to requote,
> says anything at all about physical pole shifts. All it addresses
> is a magnetic pole shift, and they say that the magnetic pole
> "probably shifted as much as 6 degrees in a single day". I am
> not sure how they get that, as they have no way of knowing
> when the various layers of lava were laid down - they did not
> necessarily occur on sequential days, or even sequential weeks.
Of course, you must be right, and they wrong, Bill. Here's the sources
referenced by the article I quoted, and perhaps they detail how these
scientists came to this conclusion.
- Coe, R.S., et al; New Evidence for Extraordinarily Rapid Change
of the Geomagnetic Field during a Reversal, NATURE, 374:687, 1995.
- Merrill, Ronald T.; Principle of Least Astonishment, NATURE, 374:674,
1995.
- Appenzeller, Tim; A Conundrum at Steens Mountain, SCIENCE, 255:31,
1992.
- Lewin, Roger; Earth's Field Flips Flipping Fast, NEW SCIENTIST, p. 26,
January 25, 1992.
> Steen's Mountain is a thrust/slip fault. If I recall correctly,
> the largest such fault in the US. This fault may have occurred
> more than 1 million years ago, and the lava may have been laid
> down even earlier than that.
Perhaps here's a clue.
The Steens Mountain Conundrum,
Science Frontiers #80, Mar-Apr 1992.
The layered lava flows of Steens Mountain, in southeastern
Oregon, have preserved video-like records of the earth's
magnetic field as it switched from one polarity to another
about 15.5 million years ago. The scientific "instruments"
here are the cooling lava flows. As they solidify from the
outside in, a process taking about 2 weeks for a 2
meter-thick flow, the lava is magnetized in the direction
of the field prevailing at the moment of solidification. We
would thus have a 2-week continuous record of the behavior
of the earth's field. Ordinarily, we would not expect to see
very much change in 2 weeks; even a reversing field is
thought to take thousands of years to complete its flip-flop.
However, at Steens Mountain, when the field reversed 15.5
million years ago, the lava flows suggest that the field's
axis was rotating 3-8° per day - incredibly fast according
to current thinking, in fact a thousand times faster than
expected.
The conundrum (one might call it a scientific impasse)
arises because the flowing electrically conducting fluids
that supposedly constitute the earth's dynamo would have
to flow at speeds of several kilometers/hour. No one has
ever contemplated molten rock moving at such speeds in
the core!