A compilation and interpretation of the second vertical derivative map from previously prepared isomagnetic maps of an airborne magnetometer survey in that part of the Great Artesian Basin between 25 30 and 28 30 S. latitude and 138 and 142 30 E. longitude. A quite detailed chapter on the purpose and theory of the second vertical derivative. Interpretation - explanation of method in this particular survey. Anomalies outlined on the basis of their expression on the records, the isomagnetic and the derivative contours, are considered to be possible manifestations of local relief on the basement surface and/or structures in the sedimentary section, and minor compositional changes in the magnetically active horizon, which three are not distinguishable in the interpretation of a magnetometer survey. Anomalies delineated as:Grade I (good reliability and good prospects of revealing structure), Grade II ( Intermediate reliability), Grade III (dubious) on basis of size, continuity, general amplitude and relationship to known structure.39 anomalies are evaluated regarding location, length, maximum total intensity, deviation and second vertical derivative.