摘要:Ⅰ.HISTORICAL CONSPECTUS For years,the Pliocene deposits of North China,have been chieflyknown by the "slopes-facies" of their lowest horizons (Hipparion richtho-feni Pontian red clays,see:Andersson 1923).Gradually however,the pre-sence of extensive freshwater formations belonging to this age,has become
