Earth and peak glaciation. Artwork of the Earth at a point of peak glaciation during an ice age, with ice caps and glaciers advanced across North America and Europe, and also seen in the Andes in South America. Peak glaciation occurs during an ice age, when glaciers and ice caps advance from the poles towards the equator. Earth has been in an ice age for the last 4 million years, but the last maximum glaciation was some 20,000 years ago. This peak glaciation ended around 10,000 years ago, with the current period being an interglacial, a warmer period where the ice caps have retreated to the polar regions.