Palaeozoic drift of Gondwana: Palaeomagnetic and stratigraphic constraints

Currently available Palaeozoic palaeomagnetic data from Gondwanan continents can be interpreted in terms of either (a) a migration of the pole from northern Africa to southern Africa between Ordovician and late Palaeozoic times, or (b) a rapid excursion of the pole from northern Africa to southwest of South Africa during late Ordovician to early Silurian times, followed by a return to central Africa in late Devonian times, thereafter continuing southward again. With respect to this uncertainty, pertinent stratigraphical evidence from western Gondwana includes the distribution of glacial deposits and cold-water and warm-water faunas. This record, although meagre and to some extent contradictory, appears to favour a drift history consistent with the second (b) of the APW alternatives that involves a rapid southerly excursion of the pole by early Silurian times.