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 ...

Two of Earth’s five confirmed mass extinction events could have been caused by nearby supernova explosions stripping the ...

This cooling event occurred during the late Ordovician period, around 445–443 million years ago, and is characterized by a significant global glaciation that led to widespread ice sheets ...