Under the dates assigned by [[uniformitarian]] geologists, it represents approximately the period of Earth's history from 1.8 million years ago to around 10,000 years ago.<ref>Gradstein and Ogg, 2004</ref><ref>Anon. (UCMP)</ref> | Under the dates assigned by [[uniformitarian]] geologists, it represents approximately the period of Earth's history from 1.8 million years ago to around 10,000 years ago.<ref>Gradstein and Ogg, 2004</ref><ref>Anon. (UCMP)</ref> |