also: だいしき
noun
Quaternary period
Geological term for the most recent period of the Cenozoic era, spanning from about 2.58 million years ago to the present.
第四紀は氷河時代とも呼ばれる。
The Quaternary period is also called the Ice Age.
第四紀の地層から多くの化石が発見されている。
Many fossils have been discovered from Quaternary strata.
Refers to the preceding Tertiary period, now largely replaced by Paleogene and Neogene in modern geological time scales.
From 第四 (fourth) + 紀 (period), a calque of the English 'Quaternary period' or its equivalent in other Western languages.