Abstract

Fifteen vertical electrical sounding (VES) stations were sounded using Schlumberger electrode configuration. The result revealed a total of 3 to 4 geoelectric layers. The first layer with resistivity values range from 2.8 to 149.2 Ωm and has thickness and depth of 0.1 to 6.5 m. The second layer has resistivity which ranges from 245.9 to 7761.2 Ωm, thickness of 1.1 to 10.7 m and depth of 1.2 to 17.2 m. This layer was observed to be more resistive than the overlain layer. The third layer was delineated with the resistivity range of 49.4 to 2161.4 Ωm, thickness of 4.5 m-∞ and depth of 5.7 m- ∞. The fourth layer has resistivity values which range from 203.3 Ωm-∞ within the maximum current electrode separation. The observed curve types are K, Q, KH and QK with K being the dominant curve type. The contour maps generated display the variation of the electrical properties of the subsurface layers. The lithology layer with clay is not suitable for building foundation due to their expansive nature while the laterite which is mechanically stable is suitable for building foundation. The lateritic layer to a depth of 1.2 to 3.0 m is considered suitable for massive engineering structures with strong base for solid foundation.

Key words: Vertical electrical sounding, construction purpose, subsurface lithology, building foundation, Makurdi.