Schematic lock-in process of a two-component (detrital and pedogenic) remanence during a field reversal. The remanence is composed of contributions (arrows) from different discrete lock-in zones separated by the lock-in isochrons (dashed). Equally shaded arrows indicate their affiliation to the respective lock-in zone. A change in magnetic polarity will be observed when more than half of the total magnetic moments are blocked in the new field direction.