Magma was injected into the rift zone along the mid-ocean ridge from the upper mantle. Subduction of oceanic crust into deep ocean trenches occurred as ocean crust cooled and sank into the upper mantle. This hypotheis explained why continents moved apart and provided a plausible mechanism for continental drift. The ocean crust should get older away from mid-ocean ridge. 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.