Fresh basaltic ocean crust and new lava flows should be found in the rift basin along the ridge crest. Inclination is the angle between the horizontal and the direction of the magnetic field lines. Polar wander - the present north pole has wandered through several degrees over the last 300 years. Rock magnetism - almost all rocks carry some magnetic minerals such as magnetite and hematite. Because of this most rocks can be magnetized if subjected to a magnetic field.
Magnetite is common in basalt and gabbro the main rocks formed along the mid-ocean ridge.
As the rocks form the record the Earth's magnetic field at the time of their formation. Paloemagnetic time scale has been created by radiometric dating of basalt and the determination of the paleomagnetism of the same samples. Magnetometers towed by ships show that the ocean crust is of both normal and reversed polarity. Study of the patterns of paleomagnetism of the ocean crust proved that Hess's sea-floor spreading model was correct. The oldest age of sediment overlying basaltic ocean crust is slightly younger than the basaltic crust it lies upon.