The distribution of the various granitoids, gneisses, schists and dykes in the St Johns Range was mapped and a representative suite of samples suitable for major and trace element analysis was collected to enable petrogenetic relationships between the rock types to be established. An area approximately 100 km2 in the central St Johns Range was mapped and approximately 120 granitoid specimens were ... specially sampled for geochemical/geochemistry analysis. Dykes of various types were mapped and cross cutting relationships were determined. Near Purgatory Peak, a 40m sequence of Altar Mountain Formation and Odin Arkose containing basal conglomerates grit and sandstones with trace fossils was observed. Lab work on rock specimens included preparation of thin sections for electron microprobe analysis of minerals and to describe the petrographic features. X-ray fluroescent analysis of the major and trace elements was completed for further refinement of the petrological features and to enable petrogenetic affinities to be determined.