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New field and chemical data for the Warrigundi Igneous Complex, Werris Creek, indicate it is made up largely of extrusive andesites, dacites and rhyolites that in part are interbedded with the upper un i ts of the Werrie Basal t. Two small dioritic stocks, two rhyolitic bosses and a dyke swarm radiating from the volcanic centre at Mount Terrible constitute the only intrusive parts of the Complex. A Rb/Sr age determined from these rocks is highly dependent on a biotite concentrate which, together with 10 bulk-rock samples, gives an agp of 269.4±4.6 Ma and an initial tl7Sr/86Sr ratio of 0.70347±0.00019. Although the age must be regarded ns tentative, it could indicate that Werrie Basalt volcanism continued Into the Artinskian. Chemical and isolopic data show that the rocks have a generally calc-alkaline character but are somewhat atypically high III TillL. Thl'y arE'probably geLlchemlcally similar to till'Werrie Basalt (Leitch et aI., 1988) but differ geochemical1y and isotopically from thp underlying Late Carboniferous lavas and ignimbrites. The low initial 87Sr/86Sr ratios together with a Sakmarian marine transgression of the Werris Creek area are consistent with a thinner crust, perhaps developed during extensional tectonics. As Benson et a1.(1920) suggested, Mount Terrible is a volcanic centre for the Werrie Basalt. A second volcanic centre is situated further to the north and produced the dacitic and rhyolitic lava and breccia of the Dunover and Piallaway Mountains.