AbstractThe paper consists of an account of a resistivity investigation into an old river valley in Coal Measure strata. This valley denuded several of the upper coal seams leaving behind unconsolidated material and it was the purpose of the work to be described to investigate how far the extent and nature of this material could be determined by resistivity methods conducted at the surface.As such the survey fits into a wider programme of research instigated by the National Coal Board.The feature, which is quite well known geologically, was surveyed by conventional methods and the results obtained are discussed in relation to the above project.Thus, the investigations succeeded in tracing the approximate centre line of the feature and in yielding some information on the nature and order of thickness of the deposits. Limitations of the method and its future application are also discussed.