The geologic period beginning two to three million years ago and extending to the present.
the cardinal number that is the sum of three and one
coming next after the third and just before the fifth in position or time or degree or magnitude; "the quaternary period of geologic time extends from the end of the tertiary period to the present"
last 2 million years
consisting of or especially arranged in sets of four; "quaternate leaves"; "a quaternary compound"
coming next after the third and just before the fifth in position or time or degree or magnitude
consisting of or especially arranged in sets of four
