Abstract

Various electrical methods now used fall under two general headings--inductive and conductive. By use of the latter methods, any theoretical depth of current penetration may be obtained by employing a sufficiently great electrode separation. However, masking effects are usually present, due both to polarization and to electrolysis. These factors may be minimized by use of a 'pulse' of current having a predetermined time-current relationship; also bothersome inductive effects are minimized by employing a slow-rising wave-front. The pulse is of long time interval to avoid any appreciable phase shift between the currents flowing along the surface (where the potential measurements are being made) and those flowing at depth (where the desired structural effect is to be obtained). Contrast and comparison is made between refraction seismic work and conductive methods of geoelectrical prospecting, with particular attention to the method of determining intensity-distance curves using a moving electrode. Optimum electrode configurations are described and briefly analyzed, as are the electrolytic temperature effects. The theory, operating technique, and interpretative technique of the continuous profiling method are given in detail. Diagrams and discussions illustrate the application of the method to detailed structural mapping, reconnaissance structural mapping, and fault location work. In some cases the method described is yielding satisfactory results in areas where other geophysical methods have failed to give interpretable data. The paper also presents a brief summary of the commercial work done during 1937 with the Jakosky pulse method.

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