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 late Ordovician event is even more murky ... its destruction by non-chemical means could send the Earth into an Ice Age. There are more earthly possible explanations to be considered as ...

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