Paleomagnetic pole
= Paleomagnetic pole
A <paleomagnetic pole> is a reconstructed geomagnetic-pole position inferred from remanent magnetic directions in rocks of a specified age, under a stated field model. In a geocentric axial dipole model, inclination $I$ gives paleolatitude $\lambda$ through $\tan I=2\tan\lambda$.
Oriented samples, age control and corrections for later deformation are essential. Stepwise thermal or alternating-field demagnetization helps separate older magnetization from later overprints. Comparing poles of different ages produces an apparent polar-wander path, which records motion relative to a continental block as well as possible field changes. An axial-dipole direction alone does not fix paleolongitude.<Rocks and Paleomagnetics Laboratory by United States Geological Survey>[Oriented sampling, shielded magnetometers and progressive demagnetization]{ref}