Final answer:
A symmetrical magnetic pattern is recorded in ocean-floor rocks across mid-ocean ridges, reflecting seafloor spreading and plate tectonics.
Step-by-step explanation:
A symmetrical magnetic pattern is recorded in the ocean-floor rocks across mid-ocean ridges. This pattern is related to seafloor spreading, which is a process where new oceanic crust is formed at these ridges and slowly moves away. As the earth's magnetic field has reversed itself many times throughout history, the iron minerals in the newly formed crust record the current direction of the magnetic field, creating a pattern of magnetic stripes. These stripes are symmetrical on either side of the ridge, reflecting the age of the rocks and the rate of spreading. This symmetrization is crucial as it provides evidence not only for the process of seafloor spreading but also contributes to our understanding of plate tectonics.