New ammonite collections from fine-grained rocks of the Laberge Group in the Whitehorse area are assigned nine ammonite zones or assemblages using the recently established North American regional zonations. Guide ammonites of these zones are illustrated. Supplemented by other published and critically revised data, the Laberge Group in the southern Yukon is shown to contain nearly all zones of the Upper Sinemurian to Lower Bajocian stages. The presence of the Hettangian and Lower Sinemurian is not adequately confirmed. In an Upper Pliensbachian section in the Miners Range, the occurrences of Fontanelliceras cf. fontanellense and Canavaria? sp. extend the known range of these taxa in North America to the Carlottense Zone. The base of the Toarcian is marked by the first appearance of Dactylioceras ex gr. simplex, which may characterize the deepest faunal level within the Kanense Zone. Another section on Goat Mountain contains a Lower to Middle Toarcian succession.
Deposition of the Laberge Group continued throughout Early and Middle Jurassic time. Conglomerates are confined to Upper Sinemurian to Upper Pliensbachian in the Takhini area and to Toarcian and older in the Fish Lake area. It is likely that Laberge Group conglomerate was not deposited in response to a single episode of relative sea level change, but to several such events during Early Jurassic time. Fine-grained clastics are Upper Sinemurian to lowermost Toarcian in the Takhini area whereas Lower Toarcian to Lower Bajocian in the Fish Lake area. Dacite tuff of the Nordenskiold formation is Late Pliensbachian in age.