Sedimentological Analysis of Coastal Sediments Along the Lagos Shoreline

The Lagos coastline is among Nigeria's most dynamic and economically significant coastal environments, yet systematic sedimentological characterisation of its nearshore and beach sediments remains incomplete relative to the scale of urbanisation occurring in the area. This study presents a sedimentological analysis of surface sediments collected along selected transects of the Lagos shoreline, South West Nigeria, with the objective of identifying sediment provenance, transport pathways, and depositional environments. Samples were collected at regular intervals along beach profiles and analysed for grain size distribution using dry sieving techniques, with statistical parameters including mean grain size, sorting coefficient, skewness, and kurtosis computed following Folk and Ward methodology. Heavy mineral analysis was conducted to identify resistant minerals indicative of source rock character. Morphoscopic examination of quartz grains under a binocular microscope provided additional evidence for transport history. Environmental discrimination diagrams were applied to differentiate aeolian, fluvial, and marine depositional settings. The study documents a general trend of fining and improved sorting in the longshore direction, consistent with persistent westward longshore drift reported for the Gulf of Guinea. Results carry implications for shoreline management, dredging operations, and the ongoing Lagos shoreline protection project. This investigation offers undergraduate students an applied introduction to coastal sedimentology in a Nigerian urban context. Keywords: sedimentology, coastal sediments, Lagos shoreline, grain size, longshore drift.