Glacials, on the other hand, refer to colder phases within an ice age that separate interglacials. Thus, the end of the last glacial period is not the end of the last ice age. The end of the last glacial period was about 11,700 years ago, while the end of the last ice age has not yet come. Over the past few million years the glacial-interglacial cycle has been paced by periodic variations in the Earth's orbit via Milankovitch cycles which are thus the cause of ice ages.