How do paleomagnetists use seafloor magnetic stripes to map Earth's history of reversals?
Quick Answer
As basalt erupts at mid-ocean ridges, iron minerals lock in the direction of Earth’s magnetic field. Matching stripes on both sides of a ridge record repeated magnetic reversals over millions of years.
The Full Story
When new ocean crust forms at a mid-ocean ridge, the iron-bearing minerals in cooling basalt align with Earth's magnetic field. As the lava solidifies, that direction is frozen into the rock, creating a permanent magnetic record. Because Earth's magnetic field has switched polarity many times, the seafloor preserves alternating bands of normal and reversed magnetism. These symmetric “magnetic stripes” helped confirm seafloor spreading and plate tectonics in the 1960s. By matching the pattern to the geomagnetic polarity time scale, geologists can estimate how fast ocean crust has moved away from a ridge.
Key Facts
YouTube Angle
Suggested video title for this topic:
"These ocean-floor stripes are the barcode of Earth’s magnetic history."
Was this answer helpful?
Tap a reaction — it helps us pick what to cover next.