Long wave-length components of the gravity and magnetic fields, topography, and heat-flow data, are examined along a trans-continent profile close to 29°S. The profile crosses from the west Australian Archaean shield in the west to the New England Permian geosyncline in the east. The depth to the Moho, the mean crustal density, and temperatures at 40 km depth and at the base of the crust are derived from the profiles. Depths obtained from seismic refraction and reflection surveys near the profile are shown for comparison. The gravity anomalies show that departures from isostasy along the profile must be small, although in the eastern part of the Precambrian shield compensation must be either regional or deeper than the base of the crust. The Moho is probably at about 35-40 km depth over most of the profile. Average crustal density estimates range from 2.82 to 2.96 t/m^3. Temperatures at a given depth increase from west to east; the depth to the Curie temperature may be below the base of the crust under the west Australian craton, but within the crust in the eastern part of the profile. The magnetic profile shows long wave-length features of some hundreds of nanoteslas amplitude; some of these correlate with gravity anomalies, others show a reverse correlation. Anomalies are generally larger in the western part of the traverse. Some anomalies appear to be caused by permanently magnetised rocks. The crust beneath the Permian New England Geosyncline is similar to that beneath the Archaean shield in Western Australia in average crustal density, elevation, and crustal thickness.
