Foraminiferal and sedimentologic data from 80 spot samples collected in Virginia and Maryland were used to investigate the paleoenvironments and biostratigraphy of the lower Eocene Nanjemoy Formation. The predominant lithology of the Nanjemoy Formation is variably glauconitic fossiliferous muddy sands, with foraminiferal abundance decreasing up section. The sediments of the lower Potapaco member are typically fine to medium-grained muddy sands containing abundant lignite and sparse glauconite. The upper Woodstock member is characterized by fine to coarse-grained sands with a decreased mud content and increased glauconite abundance.
Distributions of individual foraminiferal taxa, planktonic-benthic ratios, foraminiferal suborder ratios, and species diversity patterns were used to determine variations in the Nanjemoy paleoenvironment throughout the lower Eocene Salisbury embayment. Planktonic foraminifera place the samples sections within established biostratigraphic schemes. Supplemental evidence of paleoenvironmental variations was obtained from grain size and composition data of all samples collected.
Cluster and canonical variate analyses were used to investigate further similarities and differences in the foraminiferal content between samples, locations, and members.