HAB was the swapping of rotational poles, IIRC... This is the movement of the magnetic poles due to changes in circulation patterns in the deep mantle.
the way i understand it, the pole is wandering because of magma displacement or rotational slip which was prelude to the poles shifting to the equator along with the heavy ice at the poles centrifugal(?) action
but what do i know... 8^)
pls see link at #94