Magnetic Evidence for Seafloor Spreading

During naval missions, scientists used warships equipped with magnetometers to detect submarines and discovered strange magnetic patterns on the seafloor.

These patterns appeared as symmetrical stripes of alternating magnetic polarity on either side of mid-ocean ridges.

Scientists found that Earth's magnetic field had reversed multiple times in the past, switching the positions of the north and south poles.

When lava erupts at mid-ocean ridges, it cools and solidifies, locking in the magnetic orientation of Earth at that time.

As new seafloors form and spread outward, they record Earth's changing magnetic field, creating a pattern of alternating normal and reversed polarity stripes.

The symmetrical arrangement of these stripes on both sides of mid-ocean ridges provided strong evidence for seafloor spreading.

Scientists confirmed that the youngest seafloor is located at mid-ocean ridges, while the oldest seafloor is found farther away near deep-sea trenches.

This process supports the idea that new seafloor is continuously created at mid-ocean ridges while older seafloor is subducted at deep-sea trenches.

This discovery provided the mechanism for continental drift.