Gravity and seismic surveys conducted over a number of years in the South Australian portion of the Murray Basin are discussed in chronological sequence and related to the geology. Little is known of the pre-Tertiary geology of the area from outcrops or drilling but the geophysical work suggests a development of 7000 feet of pre-Tertiary sediments in the deepest part, northwest of Renmark. The presence of Permian in this section, interpreted from seismic refraction results has been confirmed by the drilling of A.G.C. North Renmark No. 1 Permian deposition may extend as far northwest as Canegrass Station. Gravity anomalies bear a close relationship to thickness of sedimentary section as interpreted from refraction results.