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    Re: Old stone walls record the changing location of magnetic north
    From: Frank Reed
    Date: 2019 Mar 12, 10:21 -0700

    I didn't see the link to the original article in the short "conversation" piece and missed the key point here. The claim is not that there are boundaries which were laid down to match magnetic directions but rather that the boundaries, haphazard as they are and with origins in many different orientation schemes, were recorded by surveyors with magnetic bearings. Then the stone walls provide lasting ground evidence that can be seen in aerial LIDAR surveys and referred back to those old orientations. Fair enough and not at all controversial.

    Of course we also have magnetic survey data on the town boundaries themselves which still exist in their original positions. So what does any of this analysis of LIDAR surveys yield? More detail at a level that does not impact the magnetic models? We already have this data.

    Frank Reed

       
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