ABSTRACTApproximately 700 samples from five slate, three marble and five quartzite units have been analysed for 26 elements to determine the use of geochemistry in stratigraphic correlation. Statistical treatment of the data has established that for all the slates and marbles, and certain of the quartzites, geochemistry is a viable method of distinguishing units of similar lithology. The most useful elements for distinguishing the four main slate units are P, Cr. Zn, Cu and, to a lesser extent, Rb, Sr, Y, Nb, Ba, La and Ce. Sr may indicate climatic changes or variable organic activity. The three marble units were considered as three limestone and three dolostone types. Dolostones are distinguished by high insoluble residue contents and the elements that distinguish between the dolostones are heavily influenced by these. Limestones, however, have very large differences in Sr. SiO2, Al2O3, K2O, Cr, Mn, Cu, Rb, Sr, Y and Zr have been used in discrimint function analysis. These parameters are strongly controlled by the insoluble residue with Al2O3, K2O, Cr and Rb being correlated with shaley impurities and SiO2, TiO2 and Zr with sandy impurities. Sr, Pb, Y and Zn, and to a lesser extent S and Mn, appear to be associated with the carbonate fraction.The quartzites were found to be of three major types: (1) a very variable deltaic deposit (Appin Quartzite Formation), (2) marine bodies of immature quartz sands (Glen Coe and Eilde Quartzite formations) and (3) highly mature quartz sands (Binnein Quartzite Formation and northerly outcrops of the Glen Coe Quartzite Formation). It is possible to distinguish these three types on the basis of some trace elements (Zn, Rb, Sr, Y, Ba, La, Ce) but it is not feasible to distinguish between the Glen Coe and Eilde quartzites purely on geochemistry. The Eilde Flags, an immature estuarine sandstone, has a geochemistry intermediate between that of the quartzites and the pelites, although with higher CaO, Zr and Ba than either.