How do magnetic stripes show the history of earths magnitic field?

Magnetic stripes on the ocean floor are formed as magma from the mantle rises at mid-ocean ridges and solidifies into rock. The Earth's magnetic field periodically reverses its polarity, causing magnetic minerals in the cooling rock to align with the prevailing magnetic field. These alternating magnetic orientations create stripes of normal and reversed polarity that are preserved in the oceanic crust as it spreads away from the ridges. By studying these magnetic stripes, scientists can reconstruct the history of the Earth's magnetic field reversals and the seafloor spreading process.