A glaciation is a period of time when the climate gets cold and temperature is so low resulting in glaciers or an ice sheet covering a land area. Glaciations are also called glacial periods or ice ages.
Earth has experienced many glaciations the past 2,6 million years. When a glaciation finishes the climate gets warmer and earth is in a climate period called interglaciation.
The last ice age, which often in Europe is called the Weischelian, was coldest about 22.000 years ago and it ended about 11.700 years ago.