The <xref>geological</xref> <xref>period</xref> of the <xref>Cenozoic</xref> Era immediately following the <xref>Tertiary</xref>. It is subdivided into the <xref>Pleistocene</xref> and the <xref>Holocene</xref> Epochs.
User Defined Definitions
"last 2 million years"
"the cardinal number that is the sum of three and one"
"consisting of or especially arranged in sets of four"
"coming next after the third and just before the fifth in position or time or degree or magnitude"