books.google.fr - Earth has always exhibited patterns of heating up and cooling down. At some points in time, many areas of Earth were shrouded in blankets of ice, with ice caps and glaciers dominating the landscape. Certain areas on Earth have been covered with prominent glaciers multiple times in the past for millions...https://books.google.fr/books/about/Global_Warming_Cycles.html?id=2UYrRG2ocHoC&utm_source=gb-gplus-shareGlobal Warming Cycles