this anon noticed that you observe magnetic flux lines.
You seem able to understand this concept, so…
Observing the flux lines you can see the missing link is a "torroidal shape" flow (akin to a motor's rotor) underneath the surface of the earth.
For proper poles and flux observation to collaborate, It must spin/flow in a direction that outruns the earth in the same rotational direction.
The "path and position" of the source of this magnetism correlate with a position exactly where the "zero gravity" (gravity-null/balance) point would be (considering the moon mass).
(If you consider moon/earth mass together, measuring to the "center mass" at any point will always be under the surface of earth, and at the point of this magnetic origin).
Visualize this by taking two circle cutouts, one 3x larger than other. Slide them till they touch. measure across and put a dot in the center point. (will always be on larger circle, under the surface) That is the source of earths magnetic lines. Without them, we would die from van allen radiation.
The earth's "molten" core is a torroid flow, not a ball shape. And the flow is dragged along outrunning earth by the moon. (the moon outruns the earth in same rotation)
Keep in mind the moon is not exactly equatorial orbit, it varies, as does the magnetic lines by lunar cycle…
So if you tunneled from one POLES to the other, in-between would be solid. (big surprise, our textbooks are dead wrong again)
(I hope my explaining is good enough, I can further explain if it is not clear)
Astrophysics background, with a dose of "that shit ain't right" common sense.
Flat earth cannot function in this model and does not have valid flux model.
A round/FAT earth does (fat=wide at equator)