1984 mining grid map; Eastern Ontario, Canada; proprietary info, so I can't show the whole map.
What does the notation circled in red indicate?
Is the angle related to magnetic declination? Or does it pertain to the grid lines on the map?
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Typically, the arrow marked N is true north while the arrow angled to the left indicates magnetic north. The declination is indicated by the angle 9 degrees 30 seconds placed within the angle of the arrows.
Thomas Perry
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In a related GIS Stack Exchange post (Georeferenced image type supported by ArcGIS Pro and QGIS), @GBG said:
Those values are consistent with magnetic declination. You can view a webmap here for confirming that yourself. Keep in mind that declination has changed over the years....
User1974
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