* Magnetic Field and Rock Formation: The Earth's magnetic field acts like a giant magnet, with lines of force extending from the South Pole to the North Pole. When molten rock cools and solidifies, tiny magnetic particles within it align themselves with the Earth's magnetic field at that time.
* Recording the Magnetic Field: These aligned magnetic particles essentially "record" the direction and strength of the magnetic field at the moment the rock formed. This is called paleomagnetism.
* Reversal's Impact: During a magnetic reversal, the Earth's magnetic field weakens significantly, flips its direction, and then strengthens again. As the field flips, the magnetic particles in newly forming rocks will align themselves with the new, reversed field.
* Evidence of Reversals: Geologists can study the magnetic orientation of ancient rocks to reconstruct the history of the Earth's magnetic field. They find that magnetic reversals have happened many times throughout Earth's history, with the last one occurring about 780,000 years ago.
Important Note: It's important to understand that the magnetic orientation of rocks formed *before* a reversal remains unchanged. They retain the record of the Earth's magnetic field at the time they solidified. It's the rocks forming *during* and *after* the reversal that show the flipped magnetic orientation.
