Lithostructural and Geomorphic Dataset from the Ado Ekiti Basement Complex, Southwestern Nigeria: Joint Architecture, Hillslope Morphometry, Regolith Thickness, and Residual Landform Geometry
Description
This dataset comprises 684 field measurements of lithostructural and geomorphic parameters collected from the Precambrian Basement Complex of Ado Ekiti, Southwestern Nigeria. The data were gathered to investigate the lithological and structural controls on hillslope morphology, regolith development, and residual landform evolution in a tropical crystalline terrain. Data include: Joint orientation (strike, dip, dip direction) Joint spacing and density Joint aperture Weathering rind thickness Hillslope morphometry (crest, shoulder, backslope, footslope, toeslope angles; slope length; curvature; local relief) Regolith thickness measured along hillslope positions Residual landform geometry (height, basal width, summit width, form ratio, maximum flank angle, block dimensions) Rock freshness (qualitative weathering class) Four lithological units were sampled: Granite (Gr), Granodiorite (GD), Migmatite (Mig), and Migmatitic Schist/Gneiss (MSch). Data were collected from eight purposively selected sites (two per lithology), each with paired north- and south-facing slopes, totalling 48 transects. This dataset is suitable for studies in structural geology, geomorphology, engineering geology, hydrogeology, and weathering science. It provides baseline quantitative information for understanding the morphostructural organisation of tropical crystalline terrains and has applications in groundwater exploration, geohazard assessment, and geoheritage evaluation.
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Steps to reproduce
The dataset was generated through a systematic field and laboratory protocol designed to capture lithostructural, hillslope, regolith, and residual landform characteristics across four lithological units (granite, granodiorite, migmatite, and migmatitic schist/gneiss) in the Ado Ekiti Basement Complex. Eight sites were selected using purposive stratified sampling, with two sites per lithology and paired north- and south-facing slopes. Site selection required lithological uniformity along the slope, transect length exceeding 150 m, absence of recent anthropogenic disturbance, and residual landforms within 500 m. Joint orientation was recorded at 684 stations using a Freiberg compass (±1° precision). Following ISRM (1978) guidelines, the scanline method was applied with three replicate 20 m lines at three elevations per site to estimate joint density and mean perpendicular spacing. For each joint, strike, dip, dip direction, spacing, aperture, and weathering rind thickness were recorded. Rock freshness was assigned qualitatively. To minimise observer bias, two operators independently duplicated 20% of readings, achieving >92% inter-observer agreement. Hillslope morphology was surveyed using a Sokkia CX-105 total station (±2 mm + 2 ppm) along six transects per site (three per aspect), recording elevation at 5 m intervals. Slope angles were derived over 10 m bins, slope elements (crest to toeslope) were classified following Ruhe (1960), and profile curvature was computed from second derivatives of the elevation series. Regolith thickness was measured using a 5 cm hand auger at 10 m intervals along each transect, driven to refusal or to a maximum depth of 8 m. This was supplemented by 45 road-cut and stream-bank exposures. Saprolite and colluvium were distinguished following Stallard (1995). Residual landform geometry was recorded for 12 inselbergs and 8 tors, measuring height, basal and summit widths, maximum flank angle, and joint-bounded block dimensions. Form ratio was calculated as height divided by basal width. All statistical analyses were performed in R version 4.1.2. Descriptive statistics (mean, standard deviation, range) were computed. One-way ANOVA with Tukey's HSD post-hoc test (α = 0.05) tested lithological differences, with effect sizes reported as eta squared (η²). Linear regression models were fitted with residual diagnostics: Q-Q plots, Breusch-Pagan test for heteroscedasticity, and Shapiro-Wilk test for normality (accepted at p > 0.10). Multicollinearity was assessed via VIF (threshold = 5), and standardised beta coefficients are reported. Rose diagrams and stereonets were generated using Stereonet 11 software, with all other figures produced in R using ggplot2. The final dataset was exported as a UTF-8 encoded CSV file and uploaded to Mendeley Data under a Creative Commons Attribution 4.0 International (CC BY 4.0) license.
Institutions
- Obafemi Awolowo UniversityOsun State, Ile-Ife