کواترنری

Quaternary

 

A period that encompasses at least the last 3 × 106 years of the Cenozoic Era, and is concerned with major worldwide glaciations and their effect on land and sea, on worldwide climate, and on the plants and animals that lived then. The Quaternary is divided into the Pleistocene and Holocene. The term Pleistocene is gradually replacing Quaternary; Holocene involves the last 7000 years since the Pleistocene.

The Quaternary includes four principal glacial stages, each with subdivisions, in the western Rocky Mountains and Sierra Nevada and in the north-central United States, matched by four corresponding stages throughout northern Europe and the Alps. Interglacial stages, periods of mild climate during which ice sheets and alpine glaciers disappeared, intervened between the four main glacial stages. See also: Cenozoic; Holocene; Pleistocene