The rock succession at Mt Monger, Western Australia, represents a type of Archaean volcanic ‘cycle’. The oldest rocks are a felsic-volcanic and volcanogenic-sediment association, terminated by an unconformity, representing the last stage of an earlier ‘cycle’. The new ‘cycle’ begins with a distinctive suite of ultramafic lenses and high-Mg basalts which is overlain by tholeiitic basalts before returning to felsic volcanism and sedimentation which terminates the ‘cycle’. Despite low-grade metamorphism it has been possible to reconstruct, from the well-preserved primary textures, much of the original igneous history of the rock associations and to examine their possible relationships.