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Mind Your Declination!


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#11 ski3pin

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Posted 18 May 2020 - 04:30 AM

Nova had an episode years ago called Magnetic Storm that we found fascinating. One section showed layers of basalt high up on Steens Mountain that indicated a rapid sequence of pole reversals. Minerals in the rock aligned with the magnetic field as the rock cooled. The program also showed modeling of the magnetic field. I suspect this has become much more detailed and refined since then.

I wonder if there are studies out there that tie past reversals to other global events.

I find all this so fascinating. The earth is a great place to live. :)
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#12 MarkBC

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Posted 18 May 2020 - 04:36 AM

....

I find all this so fascinating. The earth is a great place to live. :)

 

I agree.  The earth is my favorite planet! :)

 

One of the best things I did -- decades ago -- was taking a geology class from the local community college:  "Geology of Southeast Oregon".  This was a regular for-credit geology class, but I took it as audit...to avoid testing anxiety!

Besides in-class stuff we did a 4-day field trip (camping) in southeast Oregon covering Abert Rim, Hart Mt, Steens Mt and Pueblo Mt.  Mostly about all the faulting, etc, that formed the region's terrain.

Love that stuff!


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#13 PaulT

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Posted 18 May 2020 - 04:39 AM


I find all this so fascinating. The earth is a great place to live. :)

 

We've all made a very wise choice. :P

 

Paul
 


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#14 Foy

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Posted 18 May 2020 - 11:03 AM

Declination is not the only possible problem with compasses. Foy (and Magellan) in particular will appreciate this: somewhere I have a photo of my brother and I in the woods of northern Minnesota with our compasses pointing north at each other either side of a large boulder full of magnetite- a common problem here in the land of iron ore. Plays havoc with navigation in the deep woods, haha.

"Local magnetic disturbances" are fairly common.  Hard rock explorationists deal with them much more frequently since we were so often working in terrains already known to be mineralized. We encountered lots of disturbances next door to you in Michigan's UP while working in the Marquette and Iron Mountain iron ranges. As you and your brother found, there are outcrops of high iron content of ore or near-ore grade Pesky glaciers had a nasty habit of plucking them out of outcrop and dropping them miles and miles downrange.

 

Foy


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