magnetic field reversals

Changes in direction or orientation of the magnetic field of the Earth that have occurred from time to time. (Several hundred are known in the geological record.) Sometimes the north magnetic pole is near the geographic North Pole and sometimes near the South Pole in Antarctica.

Note

The causes of these reversals are not known in detail, but are thought to be related to the motion of fluids in the Earth's core.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.