Magnetostratigraphy: From a Million to a Thousand Years

Since the publication in 1600 of the book De Magnete by William Gilbert, and the measurements by magnetic observatories progressively obtained from various parts of the globe, we know that the Earth’s magnetic field is comparable to one that would be created by a bar-magnet placed at the center of the Earth and inclined by some 11° with respect to the axis of rotation.