Integrated floral and faunal (foraminiferal) data permit a precise interpretation of the age and depositional environment of the outcrop section exposed along the Calabar-Itu at 42.5 km point. The outcrop section belongs to the Nkporo Shale of the Calabar Flank from which Ariadnaesporiles nigeriensis Obebode & Skarby was reported and described. The results obtained indicate an Early Maastrichtian age and deposition in a brackish swamp environment. the biostratigraphic and environmental significance of Salviniaceous fossils have been consequently assessed.

The palynostratigraphy of the Nkporo Shale outcrop exposed at 84 km point along the Enugu-Umahia Express Way indicates a Late Campanian-Early Maastrichtian age. The spore-pollen/dinocysts ratio in the assemblage is suggestive of a brackish swamp (mangrove) environment of deposition. The relative abundance and dominance of marshy pteridophytes and palm pollen suggest the prevalence of humid tropical climate during the deposition of the Nkporo Shale.