Quaternary period (kwətûrˈnərē) [key], younger of the two geologic periods of the Cenozoic era of geologic time (see Geologic Timescale, table) from 2 millon years ago to the present. Comprising all geologic time from the end of the Tertiary period to the present, it is divided into the Pleistocene and Holocene, or Recent, epochs. It was named (1759) by Giovanni Arduino, an Italian scientist who thought that the biblical great flood was responsible for its deposits. During the early Quaternary, Europe and North America were covered by the glaciers of the Pleistocene epoch. Retreat of the glaciers led to isostatic rebound (see continent) of the crust in the Holocene. In the Quaternary the climate and present physical features of the earth continued to develop. Significant changes in sea level within historic times are demonstrated by the submergence of the temple of Jupiter Serapis near Naples and by the rising of the shores of the Baltic. The life of the Quaternary has been marked by the rise and dominance of humans.
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