The last glaciation age began about 2.5 million years ago. At this time about 1/3 of the earth’s land surface was covered in glaciers. Glaciers are large sheets of ice that build up from accumulated snowfall. During an ice age the temperature is much lower than average temperatures today. The low temperatures don’t allow for ice sheets to fully melt in the summer causing them to build and build over years until eventually a large glacier is formed. As the glaciers move they can carve out features in the land. Some scientists think that ice ages are caused by a variation in the earth’s orbit around the sun combined with a flux in the amount of carbon dioxide in the atmosphere. Although we are not currently in an ice age you can see remnants of the last ice age around the world. Places like the Antarctic, Alaska and Greenland still have some large glaciers intact!