Automatic inversion of the method of Backus and Gilbert (BG). Using a linearized iterative scheme, a layered conductivity is constructed satisfying the available soundings to an accuracy consistent with the observational uncertainties. Subsequently, in order to investigate the resolving power of the data and hence (hopefully) to determine the broad scale features which are common to all conductivity models which satisfy the data, BG average conductivities are computed for the constructed model at a number of depths. Examples with both synthetic data and field data. BG average conductivities computed for a particular constructed model will often provide a valid characterization of the true ground conductivity over a depth range governed by survey parameters.--Modified journal abstract.