THE EARTH MAGNETIC’S FIELD

• Earth’s Magnetic Field : Model– Resembles a uniformly

magnetized sphere– A simple dipole (bar

magnet)

• Polarity reversals • frequent, but highly

irregular, reversals of the geomagnetic field

• globally isochronous• recorded in sediments

and mid-ocean ridge basalts

• useful for global dating and correlation

Magnetostratigraphy

Polarity Bias of The Geomagnetic Field During The Phanerozoic.Overlapping 50 Ma

averages of polarity ratios as observed in paleomagnetic result are shown together with the limits of the standard error (After Irving

and Pullaiah, 1976)