From field observation, sporopollen analysis and
14C dating of samples collected from the Pingdingcun Section, Hebei province, the sediments involved are determined to have formed from Late Pleistocene to Early Holocene.According to an estimate of the temperature then prevailing by Fe
3+/Fe
2+ ratio and an analysis of the change of CaCO
3 content, the paleoclimate of the Yangyuan area has obviously experienced four stages in the period, i.e. warm-humid, cold-dry, cold-humid and warm-dry stages.The sporopollen assemblages reflect that a change in vegetation from forest to grass land has occurred.