#ice_age__iceage__glacial_period__glacialperiod__glacial_epoch  any period of time during which glaciers covered a large part of the earth's surface
  supertype:  geological_period__period  a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed during the earlier geological periods"
  part of:  prehistory  the time during human development before the appearance of the written word

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