The Rocksberg Greenstones are a succession of metamorphosed basic rocks, possibly originally olivine basalts and related types, forming the core of an anticline which runs north north west from Dayboro, and to the south of this town turns south eastward. The western limb, of the anticline is affected by a high-angle reverse fault (dipping east) which brings easterly dipping Greenstones against west-dipping Bunya Phyllites; the latter conformably overlie the Greenstones. On the east the anticlinal limb is faulted against Mesozoics for the whole of the length of the eastern boundary of the area. The basal section of the Phyllites in the eastern limb carries very frequent intercalations of partly metamorphosed andesitic rocks. There are also interbedded fully metamorphosed rocks which do not differ mineralogically from the Greenstones in the middle of the anticline. It is thought that this transitional zone was intruded by the andesitic rocks after the folding and towards the end of the matamorphism, which in that case would have slightly outlasted the folding.
The fault on the west is regarded as a break thrust, probably contemporaneous with the folding.
The Greenstones have been subjected, in separate areas, to at least two periods of metamorphism post-dating the orogeny. In one area porphyroblastic albite has been fanned and, probably, muscovite introduced; while in the other introduction of biotite has occurred.