Scaglia Rossa Limestone exposed near Furlo, Italy, in the Northern Apennine Mountains. is shot through with veins of magnetite which record the alignment of the rocks with the Earth's magnetic field when deposited.

The adjustment Kirshvink is studying is called true polar wander, to distinguish it from movement of the magnetic poles alone.

As the name suggests, magnetite is magnetic and preserves the magnetic field at the time at which it formed.

Just as magnetic basalt around mid-ocean ridges record the flips in orientation of the Earth's magnetic poles, leading to the discovery of tectonic plates and enabling the dating of important fossils, these magnetite veins record orientation relative to the poles.

Although the magnetic measurements can only compare movements compared to the magnetic poles, the paper's authors maintain this was true polar wander, with the whole crust tilting compared to the Earth's axis of spin.