Three major rock types are present in Nigeria: igneous, metamorphic and sedimentary. Igneous and metamorphic rocks constitute the Precambrian Basement Complex which is the oldest, crystalline, solid physical foundation of the country. Sedimentary rocks of the Cretaceous and Cenozoic age fill up the basins, which are depressions within the basement landmass. The Basement Complex and the sedimentary basins are equally dispersed in Nigeria. Quaternary to Recent age alluvial deposits occur along the main river valleys as thin and discontinuous sandy beds to thick sedimentary units up to 15 km wide and 15–30 m thick along the channels of rivers Niger and Benue, as well as along the courses of major ephemeral streams and fadamas, especially in the northern parts of Nigeria. The diverse geology of Nigeria offers opportunities for the exploitation of varied mineral deposits contained in different rock units. Abundant mineral deposits occur in all components of Nigerian geology with mineral deposits of economic significance that include gold, iron ore, cassiterite, columbite, wolframite, pyrochlore, monazite, marble, coal, limestone, clays, barites, lead–zinc, etc. The geological, structural and tectonic settings of different rock units have significant implications on the geomorphological evolution of the landscapes in Nigeria. In addition, a number of the associated geological–geomorphic features and scenery have considerable aesthetic and touristic potential, which in some cases combines with cultural importance.
