ABSTRACTNine electrode arrays were examined under controlled laboratory conditions to evaluate their relative efficiency with regard to time and space requirements, and with regard to effective prediction of subsurface conditions in electrical resistivity surveys. Of the nine investigated, the Wenner and a modification thereof (“Modified Wenner”) were selected for field testing and comparison. To a limited extent the Schlumberger array also was compared.Field testing of the three chosen arrays suggested the superiority of the Modified Wenner over the Wenner array in reliability of data obtained under most conditions examined, speed of completion of a survey and minimal straight‐line distance required for a 100‐foot (30.5‐meter) depth survey. Insufficient data were gathered with the Schlumberger array for proper comparison with the other two arrays.Subsurface conditions predicted by resistivity data were confirmed by subsurface projections of geological features suggested by previous surficial mapping, by drillers'records and by seismic refrac