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AMAZON RIVER

 
 
hamburger
 
  1  
Reply Fri 3 Nov, 2006 06:01 pm
always glad to provide to your 'amazement' Laughing !
we camped there some years ago - when we were just a bit younger Laughing . it's really quite an amazing sight .
we also walked out on the mudflats during low tide . mrs h looked at the towering rocks and wondered why there were all kinds of seaweed and shells stuck to the rocks as much as 20 feet above our heads . when i casually mentioned that the upcoming flood would reach the top of the rocks , she suggested (not so casually !) , that we might better get back on dry land !
hbg
0 Replies
 
rosborne979
 
  1  
Reply Fri 3 Nov, 2006 08:42 pm
littlek wrote:
Squinney - the poles 'flip' periodically. More specifically, the positive and negative charges change. As liquid rock comes up to fill the gap left as the oceanic rifts spread (as the continue to do), they register the polar magnetic charge. Then they harden and form the ocean floor. By looking at pieces of that spreading floor, scientists know that the charge has flipped - and that we are over due for another flip. What that means to us in our daily existence, I dunno.


The 'flips' can take several thousand years, during which time, the fields become variable and weaker.

This is not the type of event which occurs over night, or even in a single lifetime.
0 Replies
 
squinney
 
  1  
Reply Sat 4 Nov, 2006 06:27 am
I have read about the magnetic pole changes.

But, um, I was making a joke in my first post. A play on Mr. Hamburger and saying he was otherwise occupied 2 million years ago and then someone responded... Oh never mind. It isn't funny when I have explain it.

Carry on.
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hamburger
 
  1  
Reply Sat 4 Nov, 2006 10:42 am
...READY FOR NORTH/SOUTH POLE REVERSAL ?...

from the above article :
"When Compasses Point South



Magnetic Storm homepage

If all the compasses in the world started pointing south rather than north, many people might think something very strange, very unusual, and possibly very dangerous was going on. Doomsayers would have a field day proclaiming the end is nigh, while more rational persons might head straight to scientists for an explanation.

Fortunately, those scientists in the know?-paleomagnetists, to be exact?-would have a ready answer. Such reversals in the Earth's magnetic field, they'd tell you, are, roughly speaking, as common as ice ages. That is, they're terrifically infrequent by human standards, but in geologic terms they happen all the time. As the time line at right shows, hundreds of times in our planet's history the polarity of the magnetic shield ensheathing the globe has gone from "normal," our current orientation to the north, to "reversed," and back again.

The Earth is not alone in this fickleness: The sun's magnetic shield appears to reverse its polarity approximately every 11 years. Even our Milky Way galaxy is magnetized, and experts say it probably reverses its polarity as well. Moreover, while a severe weakening or disappearance of the magnetic field would lay us open to harmful radiation from the sun, there's little evidence to date that "flips" per se inflict any lasting damage (see Impact on Animals).

It might sound as if scientists have all the answers regarding magnetic reversals. But actually they know very little about them. Basic questions haunt researchers: What physical processes within the Earth trigger reversals? Why do the durations and frequencies of both normal and reversed states seem random? Why is there such a disproportionately long normal period between about 121 and 83 million years ago? Why does the reversal rate, at least during the past 160 million years, appear to peak around 12 million years ago?

All these questions remain unanswered, though experts like Dennis Kent, the Rutgers University geologist who supplied NOVA with updated figures for the time line, are hard at work trying to answer them. In the meantime, not to worry. Reversals happen on average only about once every 250,000 years, and they take hundreds if not thousands of years to complete.

Even the weakening currently under way may be a false alarm. The field often gets very weak, then bounces back, never having flipped. As Ron Merrill, a magnetic-field specialist at the University of Washington remarked when asked whether we're in for a reversal: "Ask me in 10,000 years, I'll give you a better answer." So hang on to your compass. For the foreseeable future, it should work as advertised.?-Peter Tyson "
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so put the question on your calendar and ask it again in 10,000 years :wink: . i'll try and stick around , if you don't mind :wink: .
hbg
0 Replies
 
 

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