glacial period

English Thesaurus

1. any period of time during which glaciers covered a large part of the earth's surface (noun.time)

hypernym	:	geological period, period,
definition	:	a unit of geological time during which a system of rocks formed (noun.time)

part meronym	:	prehistoric culture, prehistory,
definition	:	the time during the development of human culture before the appearance of the written word (noun.time)