The St Peter Suite has been previously interpreted to have formed in a subduction-related setting; however, there are limited data with which to assess this interpretation. This report comprises two parts. The first is a summary of Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb isotopic data collected for seven samples of igneous rocks from the western Gawler Craton. The second provides a detailed description of the lithological relationships in exposures of the St Peter Suite from Sceale Bay, westwards to Cap Rosilly and a portion of Rocky Point. The geochronology results reported here are part of an effort to assess the geodynamic setting of the St Peter Suite by providing constraints on the timeframe over which the St Peter Suite was emplaced. Six of the seven samples dated yielded ages that range from 1633 ± 4 Ma to 1608 ± 7 Ma, with one sample shown not to be part of the St Peter Suite, but rather the Hiltaba Suite, with an emplacement age of 1585 ± 7 Ma. The coastal exposures summarised in this report provide a transect across the St Peter Suite and reveal the lithological complexity of the suite. Compositions range from granite to quartz diorite, diorite and gabbro, and show that the suite comprises plutons as well as zones of magma transfer. The new data and field observations reveal the complexity of the St Peter Suite, which is composed of multiple phases of intrusion of felsic and mafic rocks across a large region of the western Gawler Craton.