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    Re: Old stone walls record the changing location of magnetic north
    From: Brad Morris
    Date: 2019 Mar 12, 13:48 -0400
    I found the article suitably lightweight, but the paper much more specific.  From it we find:

    Seventeenth‐ to nineteenth‐century land surveys of large tracts of land (from 100 to 100,000 acres) were used that showed (i) simple boundary geometries (e.g., quadrilateral), (ii) the date of the survey, and (iii) magnetic bearings of the property boundaries at the time of the land survey. LiDAR images of the area were processed to search for stone walls along the surveyed boundaries. 

    For those who wish to ignore the scribblings of a "science journalist", and wish to pursue the details, may I suggest the actual paper.


    Jackson: Thanks for bringing this to our attention.  Walls which were built along boundries, which had their magnetic bearing recorded, do indeed show correlation with the magnetic drift.

    Brad



       
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