DSK wrote:

Massive iron deposis in Canada have nothing at all
to do with compass dip. It's only that the earths
surface is not parallel to the lines of the Earths
magnetic force.

100% correct.

Closer to the poles, the magnetism
of the Earth pulls either the north or south pole
of the compass down more. Close to the equator,
the force is almost parallel.

Not really, the region of zero dip wanders about 12 degrees north and
south of the equator. Check out Chart 30 for this info?


You may be thinking about variation, which is
definitely affected by local magnetic anomalies
like massive iron deposits.

Dip is also affect by anolmalies.


Cheers MC