How are changes in the earth's magnetic field used as evidence to support seafloor spreading?

Answer 1

There is a 'striping' effect where magnetic material on the seafloor is aligned in different directions. "...during the upheaval of the Flood the flow of the molten iron in convection cells in the outer core carrying the freely-decaying electric currents meant that the resultant geomagnetic field generated would have rapidly changed direction and reversed its polarity because of that fluid movement. On the sea floor at the earth's surface new basalt lava flows were erupting rapidly due to the rifting apart of the old pre-Flood ocean floor and mantle plumes in mantle convection cells rising as a result of the catastrophic plate tectonics during the Flood. Each new basalt lava flow recorded the polarity direction of the geomagnetic field at the time it cooled. So due to the geomagnetic field reversing rapidly, and the basalt lava flows being erupted rapidly, the result was that these geomagnetic field polarity reversals were recorded in these sea floor basalts, both laterally and vertically. This paleomagnetic "striping" within the sea floor basalts was one of the key pieces of evidence that convinced geologists that the sea floor plates had spread, pushing the continental plates with them, albeit at a drift pace within their uniformitarian paradigm. However, Humphreys was able to demonstrate that because the paleomagnetic recordings of the polarity reversals were often in patches within the basalt sea floor and even within individual basalt flows, the reversals having occurred rapidly within days was a better explanation. The catastrophic plate tectonics model for the geology of the Flood thus provided a better context to explain the geomagnetic field polarity reversals. Thus Humphreys had even predicted that evidence of rapid reversals would be found before Coe, Prévot and their colleagues announced their discoveries, which of course then provided confirmation of both the Humphreys geomagnetic field model and the catastrophic plate tectonics model of the Flood. Source: AnswersInGenesis dot org article entitled 'More Evidence of Rapid Geomagnetic Reversals Confirms a Young Earth' (The above quote comes from the 14th paragraph).