A reinterpretation of the geological history of this area in the eastern Lachlan fold belt is outlined. A Late Ordovician isoclinally folded distal flysch sequence (Tallong beds) is unconformably overlain by a Late Silurian shallow marine limestone-shale sequence (Bungonia limestone). These rocks are overlain in turn by lensoidal dacite flows interbedded with shallow marine volcaniclastic and tuffaceous sedimentary rocks (Tangerang volcanics). Emplacement of the southern part of the Marulan batholith in the Early Devonian was probably coincident with broad folding. N.C.N.S.