represents the base of the Dome Creek Formation, eroded away in other parts of the area in pre-Black Stuart Group time. Mansy (1970) also mapped this horizon as Dome Creek Formation. Age and correlation. Lang (1938, 1947), Sutherland Brown (1963) and Mansy (1970) described Lower Cam- brian trilobite collections taken from the shales overlying the Mural Formation on Kimball Ridge. Mansy reinter- preted the collections of Lang (1938, 1947) and Suther- land Brown (1963) as being from the Dome Creek Formation. Lang (1938, 1947) found the following fossils which were identified by C.E. Ressor who assigned them an Early Cambrian age, except for the new genus related to Kootenia which may be Middle Cambrian; Paedeumias sp. Kootenia sp. Salterella sp. Bonnia sp. New genus related to Kootenia New genus of Ollenellid Trilobite Sutherland Brown (1963) reported: Bonnia sp. from the northwestern locality and: Ogygopsis klotzi Rominger from the southeastern locality. Determinations were made by V.J. Okulitch who assigned the Bonnia sp. to the upper Lower Cambrian and the O. K/otzi Rominger to the Middle Cambrian. Mansy (1970) collected: Ogygopsis sp. Bonnia sp. from the northwestern locality and: Ogygopsis sp. from the southeastern locality. Determinations were made by W.H. Fritz who assigned them a late Early Cambrian age. Northwest of Kimball Ridge, in the canyon of the Cariboo River, an area not mapped for this report, Sutherland Brown (1963, p. 28-29) recovered fossils from a ‘“‘black fetid limestone’’. They were identified by V.J. Okulitch as: Obolus sp. Glossopleura cf. Stenorhacis Rasetti Paedeumias (Olenellus) gilberti The brachiopod Obolus is Middle to Late Cambrian. Glossopleura cf. Stenorhacis Rasetti is Middle Cambrian and Paedeumias (Olenellus) gilberti is Early Cambrian. This faunal assemblage is probably from Dome Creek Formation. Campbell et al. (1973) reported upper Lower Cambrian and Upper Cambrian fossils from the type sec- tion in Cariboo Mountains and only one possible occur- rence of a Middle Cambrian Ogygopsis sp. They con- cluded that the Middle Cambrian may be represented by a lacuna (see Campbell et al., 1973, p. 12). Considering the presence of two Middle Cambrian trilobite indentifi- cations from the local area such a lacuna may not extend westward beyond the Cariboo Mountains. 22 Campbell et al. (1973, p. 56) suggested the Dome Creek Formation is a basinward restricted marine facies synchronous with the eastern Cambrian shelf facies of the Rocky Mountains. Similar basinal facies transitions occur in the Upper Cambrian of northern British Colum- bia where the shale facies of Kechika Formation corre- late with those of the Dome Creek Formation (see Cecile and Norford, 1979, and Gabrielse, 1975, for discussions of Kechika Formation and correlative rocks in northern British Columbia). Black Stuart Group The Black Stuart Formation as originally mapped by Mansy (1970) is here elevated to group status because it contains distinct units, three or more of which are separated by unconformities and because it spans the Ordovician to Mississippian. The Devono-Mississippian Waverly, Guyet and Greenberry formations are placed in the Black Stuart Group because they intertongue with it and/or are the same age. The Black Stuart Group is divided into three infor- mal units (following Mansy, 1970, and Campbell et al., 1973: chert-carbonate; black pelite, which both under- lies and overlies the chert-carbonate unit; and sandstone, which overlies the other two units) and into three formations. The dolostone and chert breccia of the chert- carbonate unit are unique to the Black Stuart Group. The black phyllite and argillite is generally more siliceous than other pelites of the Cariboo Terrane but similar varieties occur in the Barkerville Terrane. The association of the Black Stuart Group with volcanic rocks of the Waverly Formation and conglomerate of the Guyet Formation distinguishes it from older units. The Black Stuart Group primarily underlies the area southeast of Antler Creek, being best exposed and most diverse near Black Stuart Mountain. Black pelite of the group continues northwest in a thin belt to Big Valley Creek. The Black Stuart Group was first named and described by Mansy (1970) as a formation in the Black Stuart Mountain area. Campbell et al. (1973) recognized equivalent strata to the north of Cariboo River and mapped them as far north as Antler Creek. The only other locality where Black Stuart Group is known is at Haggen Ridge northeast of the map area. Mansy and Campbell (1970) reported a thickness of approximately 850 m in the type area. Though Campbell et al. (1973) did not report any total thickness they considered the group to be less than 850 m. South of Cariboo River, the Black Stuart Group is probably less than S00 m thick. In the Cunningham Creek area, southeast of Mount Tinsdale, the group may be thicker, but this may be due to structural complications. Chert-carbonate unit The chert-carbonate unit consists of various types of dolostone, dolostone breccia and conglomerate and chert