Throughout the Earth’s history, there were quite a few of occasions when most of the northern hemisphere got blanketed by enormous amounts of ice and snow. These periods get classified as ice ages. Throughout the time of the ice ages, masses of slow moving glacial ice engulfed the land. These masses could get up to one mile long! Around twenty-thousand years ago during the peak of the last ice age, where Canada is today, a whopping ninety-seven percent of it got blanketed with ice.
An ice age can take place in the event the average daily temperature falls below just a few degrees Celsius for a considerable period. In an ice age, there are variations in temperature. The cold periods get called glacial periods where glaciers and sheets of ice quickly increase. The snow gets unusually deep, and the bottom layer turns to ice. This ice is so heavy that the sheets of ice travel throughout the land. The warm periods get called interglacial periods, where glaciers and sheets of ice reduce in size.
Our Planet is currently in an ice age which began about two million years ago. This gets referred to as the Quaternary Period. Regardless of the numerous amounts of warm periods, it is still considered one ice age. This is due to the continual occurrence of at least one sizeable sheet of ice over Antarctica. At present, the earth is experiencing a warm period. The climate signifies an interglacial period that started about ten-thousand years ago. The last glacial period the earth had lasted for eighty-thousand years.
There have been seven ice ages identified so far. Four of which are noteworthy because of how long they lasted and the magnitude of their glaciation; the Huronian Ice Age, The Crogenian Ice Age, The Karoo Ice Age and the current Quaternary Ice Age.