[pct-l] North magnetic pole is adrift

[Bighummel at aol.com (Bighummel@aol.com)]

This is really cool, because back in the early 1970's researchers were 
drilling the ocean floor in the east Pacific and found that the magnetic orientation 
of strips of volcanic basalt ocean floor flipped back and forth.  This and 
other information about the age of these rocks firmly established the plate 
tectonic theory.  In essence, every so often (several million years, I don't 
recall exactly) the magnetic poles switch.  This doesn't happen suddenly, but over 
a long period wherein the poles follow a tortured path.  An article in Earth 
magazine several years ago had plots of the paths that the poles took for 
several of the most recent reversals.  They were able to patch these together by 
taking the magnetic orientation of numerous volcanic rocks around the world, all 
of which solidified about the time of the magnetic reversals.  Volcanic rocks 
record the magnetic orientation when they solidify due to the magnetic 
materials within them lining up to point towards the north pole where it is when the 
cooling of the rock happens.

There has been much speculation what a magnetic reversal would mean to 
migrating birds that depend upon the magnetic field and all of our electronic 
mechanisms these days.

Greg "Strider" Hummel
(who happened to get his trail name from the extremely long stride evident in 
the mud near Campo, noticed by hikers who came behind me in the year that I 
hiked)