Preliminary results concerning the stratigraphy and geochemistry of the Barby Formation volcanics from the type locality of the Sinclair Sequence are briefly presented. The Barby volcanics have, on petrological and geochemical grounds, been subdivided into two geographically distinct successions. The southern succession is considered to represent typical Barby Formation, whereas that in the north is inferred to overlie the southern succession. The southern region has a well-defined base where the Basal Volcaniclastic Member forms a widespread marker horizon directly overlying the Kunjas Formation. Above this Member the succession is characterized by 'porphyritic lavas which show a complete compositional range from basaltic andesite to rhyolite. Together with thin intercalated pyroclastic deposits, these volcanics appear to have been deposited in elongate basins separated by syndepositional faults. The northern succession consists of bimodal sequences of aphyric basalt and thick pyroclastic rhyolite within which sedimentary units are intercalated. Major and trace element data for these successions reveal two discrete chemical trends which support this subdivision of the volcanics. The southern volcanic sequence has potassium-rich calc-alkaline affinities, whereas the northern succession is tholeiitic. Trace element data suggest stratigraphic correlation between the northern succession rhyolites and the Guperas Formation rhyolites, which in the south directly overlie the southern volcanic succession.