A PROPOSED NOMENCLATURE FOR STAGES AND SERIES FOR THE CAMBRIAN OF LAURENTIA

An internally consistent succession of six named regional stages (from youngest to oldest: Sunwaptan, Steptoean, Marjuman, Delamaran, Dyeran , Montezuman), with their boundaries defined by regional extinction ev ents within the trilobite record, is proposed for the trilobite-bearin g rocks of Laurentia. Sub-trilobite stage(s) are recommended but unnam ed. The three youngest stages have been named previously, but the lowe r boundary of the Marjuman is shifted downward. The three older stages within the trilobite record are new. If deemed necessary, four region al series are also suggested (from youngest to oldest: Millardan, Linc olnian, Waucoban, and Begadean); each of the three youngest series acc ommodates two stages.