CRETACEOUS GEOLOGY OF THE CAPE FEAR RIVER VALLEY (PART B): FROM WALKERS BLUFF TO HOOD CREEK LANDING, NORTH CAROLINA

For over 100 years, Cretaceous age outcrops exposed along the banks of the Cape Fear River have been used to characterize the regional Cretaceous geology of the Carolina Coastal Plain. Although recent field guidebooks document the geology of selected outcrops, a comprehensive study of the entire river valley from the Fall Line to the coast has not been attempted since the early 1900’s. For this study, twelve outcrops from Walkers Bluff (milepost (mp) 60.0) to Hood Creek Landing (mp 18.6) were analyzed for sediment characteristics and biostratigraphic content (palynomorphs and calcareous nannofossils). Outcrops were photographed, described, and measured with respect to mean sea level. Scintillometer profiles were recorded to aid in the correlation and identification of formations. Ratios of marine and terrestrial palynomorphs were calculated and used to distinguish between weathered marine and fluvial sections. Planktic/benthic foraminiferal ratios were calculated for marine sections and used as an indication of paleodepth. Formations were identified and correlated to formations elsewhere in South and North Carolina, and their unconformable contacts were traced from upriver to downriver using changes in lithology, depositional environment, color, and lag deposits. Palynomorphs from the Bladen Formation at Walkers Bluff place the sediments in upper Campanian pollen zone Ca. The contact between the Bladen and Donoho Creek Formations is located at Donoho Creek Landing (mp 50.2). Late Campanian palynomorphs and calcareous nannofossils place the Bladen in pollen zone Ca and nannofossil Zone CC21 and the Donoho Creek in upper Campanian zones Oa and CC21/22c. The contact between the Donoho Creek and Peedee Formations is located at Black Rock Landing (mp 36.8). Palynomorphs and calcareous nannofossils place the Donoho Creek in upper Campanian zones Oa and CC22c, respectively, and the Peedee in upper Maastrichtian zones Ct and CC25a. Pollen zone Hc was identified at Neils Eddy Landing (mp 27.8). Uppermost Maastrichtian strata (pollen zone Su and calcareous nannofossil Zone CC26) do not crop out on the river.