
Old Stone Walls Reveal How Earth’s Magnetic North Changes over Time - pseudolus
https://www.citylab.com/life/2019/03/old-stone-walls-reveal-how-earths-magnetic-north-changes-over-time/584914/
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aristophenes
Wow. Most property metes and bounds are described using compass readings, at
least in New England. Often only one point or one side of a large tract is
defined from a relative fixed point, such as a road, then it's all compass
directions with lengths that should match with neighboring properties. The
original farms have been sliced up into smaller lots for homes, but they are
usually directly based on the property lines described a couple hundred years
before. This is telling me that probably most people, at least in New England,
have incorrect property lines, larger properties could have very large
deviations. The author mentioned a 6.6 degree difference in 250 years, that is
a big difference.

Surely surveyors must already be aware of this? Or do they just assume that
the old records were done shoddily, and fudge their results by looking at the
accepted property lines?

Fortunately, many states have "squatters rights" which says, if you think you
own a piece of property, and act like you own it, and other people act that
way to, then after some amount of time (20 years or so), it legally belongs to
you. This is not to allow people to steal property, but to clean up mistakes
in the land records if things weren't filed properly. Or if what "North" is
changes, apparently. Otherwise, by strict definitions, I bet there are lots of
houses where technically half the house is in the neighbors yard.

Interestingly, the change over time will be different in different places
around the world, due to their relative distance from magnetic north. Magnetic
north has been hanging out in northern Canada, so Canada and the northern US
will be most affected, along with other places in really high latitudes.

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bitxbitxbitcoin
This can't just be an American happenstance can it?

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caymanjim
The magnetic drift affects the entire globe. Whether the phenomenon exists
elsewhere depends on how common building walls along magnetic compass lines
has historically been. I wouldn't be surprised if it were more prevalent in
colonial America. Much of Eurasia was divided up earlier, and much of the rest
of the world later. This is pure speculation, but I wouldn't be surprised if
the window of "compass-driven surveying" was brief. Likely the author just
focused on his neighborhood, though.

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Ericson2314
There are presumably other colonies where prior property boundaries, if they
existed, we're ignored.

