GLACIAL EPOCHS

(Geology) Any of those parts of geological time, from Pre-Cambrian time onward in both the Northern and Southern hemispheres, during which a much larger portion of the earth was covered by glaciers than at present. More specifically refers to the latest of the glacial epochs, that of the Quaternary period, known as the Pleistocene Epoch, beginning some 3 million years ago, during which Canada, northern and northeastern U.S., northern and northwestern Europe, and northern Asia, together with most high mountain regions in the Northern Hemisphere were largely covered with ice. It has been divided into a number of stages. Those recognized for the interior of North America are, in order of age: Jerseyan or Nebraskan (glacial); Aftonian (interglacial); Kansan (glacial); Yarmouth and Buchanan (interglacial); Illinoian (glacial); Sangamon (interglacial); Iowan (glacial); Peorian (interglacial); Earlier Wisconsin (glacial); an unnamed (interglacial) interval; Later Wisconsin (glacial); Champlain (glaciolacustrine epoch).