Port Julia 1A was recently drilled by BHP Minerals in EL 1112 to investigate a bullseye magnetic anomaly, but failed to realise its mineral-related objective. The well was fully cored through the Cambrian Coobowie Limestone, Moonan Formation and Stansbury Limestone, which unconformably overlies Proterozoic basement rocks. Out of drilling elsewhere on Yorke Peninsula (e.g. Stansbury West 1, Edithburgh 1) only short cores, cuttings and wireline logs are available for calibrating petroleum-related basin studies, so this new, continuous suite of core is critical for refining our biostratigraphic and sequence stratigraphic interpretation of the Stansbury Basin succession in the area. Faunal evidence gained so far from Port Julia 1A has for the first time in South Australia been able to establish the position of the Early Cambrian / Middle Cambrian stratigraphic boundary. Additional information concerning two previously uncorrelatable regional Early Cambrian depositional sequences represented by the Ramsay Limestone - Moonan Formation succession has also been revealed by inspection of core from this well.