Subsurface Stratigraphic Mapping Using The D.C Electrical Resistivity Around Shika, Kaduna State, Nigeria.

Electrical resistivity investigation was carried out around Shika, Kaduna state, Nigeria in order to delineate the subsurface geologic strata with a view of determining the depth to the bedrock and thickness of the geologic strata. Vertical Electrical Sounding (VES) using Schlumberger array was carried out at eighteen (18) VES stations. ABEM terrameter (SAS 300) was used for the data acquisition. The field data obtained have been analysed using computer software (IPI2win) which gives an automatic interpretation of the apparent resistivity. The VES results revealed heterogeneous nature of the subsurface geological sequence. The geologic sequence beneath the study area is composed of hard pan top soil (clayey and sandy-lateritic), weathered layer, partly weathered or fractured basement and fresh basement. The resistivity value for the topsoil layer varies from 60Ωm to 373Ωm with thickness ranging from 1.06 to 4.14 m. The weathered basement has resistivity values ranging from 70Ωm to 708Ωm and thickness of between 1.77 to 33.04 m. The fractured or partly weathered basement has resistivity values ranging from 318Ωm to 834Ωm and thickness of between 12.9 to 26.3 m. The fresh basement (bedrock) has relatively high resistivity values ranging from 1161Ωm to 3115Ωm with infinite depth. However, the depth from the earth’s surface to the bedrock surface varies between 3.32 to 36 m. The study further stressed the importance of the findings in engineering, groundwater exploration and waste disposal problem.