Ice Age normally refers to the most recent freezing period that occurred 20,000 years ago. In this era, large portions of North America and the Eurasia continent were covered with ice. However, the true definition is a specified time of lower temperatures on Earth that created ice sheets and glaciers. Researchers use geological (studying rocks), chemical (composition of fossils) and paleontological (location of fossils) evidence to describe all the ice ages that occurred through the years. There have been at least five ice ages on Earth. View the videos below to better understand ice ages.
Videos
Learn about the fascinating history of the Ice Age in Europe.
Follow along as scientests ask questions about the Ice Age.
What would happen if our world froze over today? Has it happened before? National Geographic walks you through this question.
A time lapse of Anarctica condensed into 6 minutes.
