Paleomagnetism

As igneous rock cools, iron minerals within the rock align much like a compass to the magnetic pole. Scientific research has shown that the magnetic pole periodically, over hundreds of thousands of years, reverses polarity.

Under normal polarity, alignment is to the North. When the polarity is reversed, alignment is to the south.

Research also shows that the bands of rocks on either side of a spreading center are mirror images of each other with regards to magnetic polarity. And, that the alignment of minerals indicate a periodic shift in polarity. The reversals in polarity can be visualized as alternating "stripes" of magnetic oceanic materials.

This graphic shows the mirror image of rock formations on the sea floor as they move laterally away from each other on either side of the spreading center.