NOTEONTHEYUEHMENKOUSERIESINTHEWESTERNHILLSOFTAIYUAN,CENTRALSHANSI

IntheconsiderationofthePermo-CarboniferoushistoryofEasternAsia,theYuehmenkouseriesstandsoutasanunitofwideextentbothstratigraphicallyandpalaeontologically.ThenameYuehmenkouserieswasfirstgivenbyDr.Norinin1922asawholecoal-bearingformationofCentralShausi,whichwasdividedintotwoparts--alower,theTaiyuanseries,andanupper,theShansiseries.Thetype-localityofthisformationistheYuehmenkou,intheWesternHillsofTaiyuan.TheTaiyuanseriesiscomposedmainlyofshale,variegatedclay,sandstone,importantcoalseamsandafewinterstratifiedmarinelime-stones.ThesamemaybesaidtobethecaseintheShansiseries,butthereseemstobeonlyonelayerofmarinelimestone,theTungtayaoLimestone,lo-callydevelopedatthelowerpartofthisseries.Thepreliminarystudyofthepalaeozoologicalremainscontainedinthemarinebedsofthisformation,leadsProf.GrabauandDr.Norintoconsideritslowerpart,i.e.,theTaiyuanseriesasrepresentingthetransitionfromViseentoMoscovian,withoutbeingasyettrueMoscovian,anditsupper,i.e.,theShansiseriestobeofPermo-Car-boniferousage.