The area around the Ilokun dumpsite, Ado-Ekiti was investigated with the aim of establishing the possible impact the contaminant plumes emanating from the dumpsite have on the subsurface aquifers. The Vertical Electrical Sounding (VES) field technique of the electrical resistivity method was adopted for the study, and the half-electrode spacing AB/2 varied from 1 to 65 m. A total of eight VES stations were occupied and a control VES point was located on the refuse dump. The VES data were interpreted quantitatively by partial curve matching and computer iteration, after which the geoelectric parameters were used to evolve a 2-Dimensional geoelectric section beneath the study area.The weathered layer beneath the control VES point was identified to be the aquifer unit, but the anomalously low resistivity of 18 ohm-m within the unit was interpreted as an evidence of pollution from conductive contaminant plume. The geoelectric section beneath VES 1 to 7 delineated four layers, these include the topsoil; the weathered layer; the fractured basement and the fresh basement. The resistivity and thickness range of the layers are 177 – 399 ohm-m and 0.7 – 1.2 m; 29 – 842 ohm-m and 1.0 – 3.4 m; 16 – 446 ohm-m and 4.5 – 45.5 m; and 289 – 2144 ohm-m respectively. The fractured layer constitutes the main aquifer unit beneath the seven VES points, but the anomalously low resistivity of 16 – 47 ohm-m within the fractured layer beneath VES 4, 5, 6 and 7 is suspected to be as a result of pollution from conductive contaminant plume emanating from the dumpsite. The fractured layer beneath VES 2 and 3 which does not show any evidence of pollution yet is at a risk of being contaminated, due to its interconnection with the polluted zone.

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The petrography and geochemistry of Orin-Ekiti Basement rocks were evaluated to determine their mineralogical and chemical composition, assessed their petrogenesis and susceptibility to the formation of bauxitic clay. Ten representative rock samples were selected for thin section petrography and bulk rock geochemical analysis using Petrographic microscope and XRF, Rh Tube, 3k Watt respectively. Field observations revealed charnockites as the dominant rock in the study area with other lithotypes including granite, granite gneiss and banded gneiss. Optical examinations indicated the dominance of quartz in all the rocks suggesting the rocks are product of acidic magma. The order of oxides concentration (wt%) is SiO 2 >Al 2 O 3 >Fe 2 O 3 >CaO>K 2 O>MgO>Na 2 O>TiO 2 >P 2 O 5 . Based on silica content only, the rocks in this study are classified as felsic (granite, granite gneiss and banded gneiss) with SiO 2 >65% and ultramafic (charnockites) with SiO 2 <45%. Charnockites with low SiO 2 , high Al 2 O 3 and TiO 2 compared to other rocks in the study area is considered more favourable to form bauxite. The rocks in the study area are classified into calcic-alkali and calcic groups with igneous protolith.