Complex sentence: As the Ordovician progressed, we see evidence of glaciers on the land we now know as Africa and South America, which were, at the time near the South Pole, and covered by ice caps.
Split into simpler sentences: As the Ordovician progressed, we see evidence of glaciers on the land we now know as Africa and South America. At the time these land masses were sitting at the South Pole, and covered by ice caps.