Ice ages are long periods of time when Earth’s average temperature drops. The Great Ice Age lasted for more than 2 million years. During its peak, the planet was about 10 degrees colder than it is today. You may not think that’s a big deal. But small changes in Earth’s temperature can cause major changes to the planet. 

During the Great Ice Age, lakes and oceans became icy plains. At times, ice sheets called glaciers covered about a third of Earth’s land. This included Canada and much of the northern United States. That means, long ago, the place you call home may have been locked under ice!

It would have been a dangerous time to be alive. Just ask the early humans who lived back then. They took shelter in caves to stay warm. (That’s where the term cavemen comes from!) 

Our early relatives painted images onto cave walls. This cave art gives us a snapshot of what life was like back then—a world of endless, icy winters and mega-beasts. Hunters hurled sharpened spears at terrifying monsters. This was the age of elephant-size woolly mammoths and 600-pound woolly rhinos. And don’t forget about that saber-toothed tiger. Aah!