Quaternary refers to the period of Earth's history from about 2 million years ago to the present; also, the rocks and deposits of that age. Quaternary refers also to a geologic period that occurred roughly 1.6 million years ago to today. During much of this period continental glaciers in the Northern Hemisphere covered large regions of land surface in the high and mid-latitudes. Homo sapiens appear about 200,000 years BP (before present) and become the first species to alter the Earth's environment on a large-scale.

-see also:
"Quaternary" is in the HS Code "2923"
  Quaternary Ammonium Salts And Hydroxides ; Lecithins And Other Phosphoaminolipids
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List of books: Quaternary

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