Manasquan/Lower Shark River Formations

Deepest water depths of the Cenozoic were attained in lower to lower middle Eocene sequences. Water depths, determined using benthic foraminiferal biofacies (Browning, et al., 1997), show middle to outer neritic paleodepths.  Sequences consist of very thin glauconitic clays overlain by carbonate-rich clays with layers of porcellanite interspersed. Sequence boundaries are inferred by matching the few surfaces in the cores with biostratigraphic breaks. Above the lower/middle Eocene boundary, there are three, thin, glauconite-rich sequences.  The lower-middle Eocene, although still carbonate rich, is slightly shallower (middle neritic), and sequences can be more easily distinguished lithologically particularly by basal glauconite sands.

Manasquan Formation along the Manasquan River, Howell, NJ.

Shark River Formation (with Kirkwood Formation) along the Manasquan River, near Farmingdale, NJ.