But once Gondwana took up its polar position in the late Ordovician, massive glaciers formed over Africa at the supercontinent's center. This heralded a 20-million-year ice age during which ...

The Ordovician event is believed to have wiped ... they are unlikely to bring another ice age anytime soon. Watch Live TV in ...

The Ordovician event is believed to have wiped ... they are unlikely to bring another ice age anytime soon.