- ice age, glacial period, glacial epoch - any period of time during which glaciers covered a large part of the earth's surface; "the most recent ice age was during the Pleistocene"
--1 is a kind of period, geological period
--1 is a part of prehistory, prehistoric culture - Pleistocene, Pleistocene epoch, Glacial epoch - from two million to 11 thousand years ago; extensive glaciation of the northern hemisphere; the time of human evolution
--2 is a kind of epoch
--2 is a part of Quaternary, Quaternary period, Age of Man