Sediments intersected by water bores and petroleum wells in the Great Artesian Basin generally have concentrations of less than 1% P205, but several between 1% and 11% and one sample with 27.6% P205 were determined; these were recorded from Mesozoic (Albian and Aptian) strata. Analyses of sediments from petroleum wells where gamma ray logs showed anomalous radioactivity do not suggest a link between phosphate and uranium within the Basin. Concentrations of phosphate in outcrops of lower Cretaceous strata between Oodnadatta and Marree and in the Moolawatana - Gardiner area were generally less than 1%. The best three samples contained 22.65%, 7.20% and 7.40% P205; further sampling and drilling to shallow depths to trace the extent of these anomalies is recommended.