Question

explain how rocks on the seafloor record magnetic reversals over time.​

Answer 1

At sites of seafloor spreading along divergent plate boundaries, this crust is separated into parallel bands of rock by successive waves of emergent magma. When Earth's geomagnetic field undergoes a reversal, the change in polarity is recorded in the magma.

Source: https://kids.britannica.com/students/assembly/view/194471

Answer 2

During a process called sea floor spreading the oceanic crust separates and spreads apart along a mid-ocean ridge.