TAGRA 2025

This study employs electrical resistivity methods—Vertical Electrical Sounding (VES) and 2D Electrical Resistivity Imaging (ERT)—to delineate subsurface peat and clay deposits in Orile Whitesand, Orile–Iganmu, Lagos State, Southwestern Nigeria. A total of twenty-four (24) VES and eight (8) 2D resistivity profiles were acquired using a PASI Terrameter (Model 16GL). The Schlumberger array was utilized for VES and the Wenner array for 2D imaging. Data were processed using WinResist 1.0 and DIPROFWIN software to generate geoelectric sections and resistivity models. Results revealed four to six distinct subsurface layers, notably topsoil, clay, peat, sandy clay, clayey sand, and sand. Peat was identified by its extremely low resistivity values (0.3–9.6 Ωm) and variable thickness (1.7–27.2 m), while clay exhibited resistivity values ranging from 11.1 to 31.9 Ωm with thicknesses of 1.3–27.3 m. In several VES stations (e.g., 10, 12, and 14), current penetration was insufficient to resolve complete peat layers, indicating highly resistive overburden or localized saturation anomalies. The 2D resistivity profiles provided enhanced lateral continuity and confirmed the spatial distribution of low-resistivity peat and clay zones. The presence and distribution of these materials are critical for environmental and hydrogeological planning due to their influence on groundwater flow, contaminant retention, and foundation stability. The study recommends complementary hydrochemical analyses to evaluate groundwater quality in relation to the identified peat and clay zones.