The third (0.17–0.12 Ma) of four glacial stages recognized in North America. It is represented by deposits from ice moving from the north-east, and in formerly glaciated areas to the west pollen evidence suggests that mean annual temperatures were 2–3°C cooler than they are now. At the end of this period the climate became warmer and drier. The Illinoian is approximately equivalent to the Mindel and Riss glacials of the Alps.
Subjects: Ecology and Conservation — Earth Sciences and Geography.