The Quaternary (a term introduced by A. Morlot in 1858) is a geological period of the Cenozoic and spans, approximately, the last two million years of the Earth's history. The exact duration is a matter of debate; estimated between 1.8 million years and 2.6 million years by different authors. The Tertiary/Quaternary boundary is defined by the Vrica section (1.806 million years BP), a type locality in from Calabria, Italy. The Quaternary is subdivided into the Pleistocene: 2 million years BP to 10 000 years BP, and the Holocene: 10 000 years BP to the present.

Note: all ages are given as conventional ¹⁴C-years BP; e.g. 10 000 years BP correspond to 11 500 calendar years before present.

The Quaternary is a geological period with dramatic and frequent changes in global climate and the period during which much of hominid evolution took place. The overriding controls on the vast variations in climate during the Quaternary are three predominant characteristics of the Earth's astronomical position relative to the sun, which vary cyclically over time on different wavelengthsand cause variations of up to 20% in the total sun-radiation reaching Earth’s surface (Milankovitsch theory). The glacial cycles were strongly driven by the astronomical variables.  An Antarctic ice core provides data about climate conditions back to 750 000 years ago. This ice core records eight glacial cycles that have been characterised by long periods (c.100 000 years) of cold climates interspersed with shorter periods (c.10 000 - 28 000 years BP) of warmer conditions.