Final answer:
Magnetic stripes on the seafloor are symmetric about the ridge axis and indicate magnetic field reversals. The spreading rate can be used to calculate the historical timeline of these reversals and the rate of continental drift.
Step-by-step explanation:
Magnetic stripes on the seafloor are symmetric about the ridge axis along which they were created. The pattern of these magnetic stripes provides evidence for periodic reversals of the Earth's magnetic field. The magnetization of basalts, which form new seafloor at spreading centers like the mid-Atlantic ridge, records the direction of the Earth's magnetic field at the time of their formation.
The spreading rate of seafloor is crucial because it can be used to calculate the rate at which geological events have occurred. By understanding the spreading rate of the mid-Atlantic ridge and the age of magnetic stripes, scientists can develop a timeline of the Earth's magnetic field reversals.