The Materials Department of the Iowa State Highway Commission has been experimenting with the electrical earth-resistivity method of geophysical exploration. During the summer of 1955 a full time crew ran extensive tests over various selected locations throughout the state of Iowa. The purpose of this investigation was to evaluate and demonstrate the use of earth resistivity in preliminary subsurface reconnaissance by providing subsurface information useful in determining location, design, and construction of highways. Experiments were made with both the depth profiling and the constant depth resistivity traverse methods of field operation. Three methods were used for analysing the field data: the Gish-Rooney (1925) or apparent resistivity curve, the cummulative resistivity technique developed by Moore (1945), and the individual layer or specific resistivity method devised by Barnes (1952). These methods will be described in the text. The authors would like to point out that the following report is not a final analysis, but should be considered as a progress report of the initial years work
