It would create a symmetrical pattern of magnetic stripes, with normal and reversed polarity, on either side of mid-ocean ridges.
Explanation:
When lava erupts at a mid-ocean ridge, it cools down and hardens into rock. This rock contains iron, and as the rock cooled and hardened, the iron in it lines up in the direction of the Earth's magnetic poles. Scientist have recorded the magnetic memory of rocks on both sides of a mid-ocean ridge using sensitive instruments like Magnetometers, and found that stripes of rock that formed when Earth's magnetic field pointed North alternate with stripes of rock that formed when the magnetic field pointed South, and the pattern is the same on both sides of the ridge. This provides evidence of seafloor spreading, and also of magnetic polarity reversal. Scientists learned that the Earth's magnetic poles have reversed themselves nine times in the past 3.5 million years.
Scientists mapped the magnetic polarity of ocean floor on both sides of the ridge. They found that the pattern of strips of rock with the same polarity matched on both sides of the ridge. This showed that the ocean floor moves away from mid-ocean ridges as new rock forms.
