The stratigraphy and geological relationships of upper Paleozoic limestones in the Cariboo gold belt are discussed in the light of 49 new conodont collections. Combined with lithological criteria, these define three units: the Lower Mississippian Greenberry Formation, the new Alex Allan Formation, and the new (informal) Sugar limestone. The Greenberry Formation is largely an upper Tournaisian limestone composed of transported bioclastic debris that was deposited in shallow water. Limestone of the Alex Allan Formation disconformably overlies the Greenberry Formation and contains a mixed conodont fauna representing the Early and Middle Pennsylvanian and possibly the Late Mississippian and Late Pennsylvanian. The mixing is ascribed to the influx of eroded Mississippian? and Pennsylvanian strata. Where observed, the Greenberry and Alex Allan Formation limestones are less than 30 m thick, and they apparently represent deposition during anomalous sedimentary pulses in an otherwise nondepositional interval. Conodont faunules from both limestones include many elements previously unrecorded in western Canada, the most notable of which are Mestognathus from the Greenberry Formation and Gondolella and Neogondolella from the Alex Allan Formation. The Wolfcampian crinoidal Sugar limestone is spatially and apparently structurally and stratigraphically unrelated to the Greenberry and Alex Allan formations.