Samples were taken at 35.4 ft (10.8 m), 61.5 ft (18.8 m), 71.1 ft (21.7 m), 73.6 ft (22.4 m), 84 ft (25.6 m), 100.3 ft (30.6 m), 110.4 ft (33.7 m), and 120.7 ft (36.8 m) in the marine section above the Magothy Formation. The only samples that contained nannoplankton were 61.5 ft (18.8 m), 71.1 ft (21.7 m), and 73.6 ft (22.4 m). These samples contained Aspidolithus parcus constrictus (first occurrence [FO] in Zone CC18) but lack Marthasterites furcatus (last occurrence at top of Zone CC18) and Ceratolithoides aculeus (FO at the base of CC20), which places them firmly in Zone CC19. The background assemblage is Campanian.
Eleven nonmarine samples were analyzed from the Fort Mott corehole by G. Brenner for palynomorphs, pollen, and spores (Table T3), and preliminary examination was made of 16 samples from the Potomac Formation by P.P. McLaughlin. Sample recovery was variable (5 of 16 examined by McLaughlin were barren), but several samples recovered a well-preserved flora. Samples are assigned ages using the zonations of Brenner (1967) (Figs. F2, F4, F5, F6, F7) and Doyle and Robbins (1977). A sample at 137.5 ft (41.91 m) is assigned to Zone V; because it lacks advanced Normapolles, it is interpreted as late Turonian. Samples between 157 and 162.8 ft (47.85 and 49.62 m) are assigned to Zone III and interpreted as early Cenomanian. Zonal assignment of the sample at 435.4 ft (132.71 m) may be either Subzone IIC (late Albian) or possibly Zone III (early Cenomanian). Samples between 465.4 and 500 ft (141.85 and 152.4 m) were assigned to Subzone IIC (late Albian). Samples between 556.2 and 577.2 ft (169.53 and 175.93 m) were assigned to Subzone IIB (Albian). The biostratigraphic assignment of samples from 599.3 ft (182.67 m) and 641.1 ft (195.41 m) is equivocal and could be either to Subzone IIB or to Zone I. Brenner (this study) assigned both samples to Zone I (Aptian) based on the apparent absence of tricolpate pollen, tricolporate pollen, and pteridophyte spores typical of Zone II in the Patapsco Formation of Maryland. In addition, he notes an increase in the pollen of Classopollis, Eucommiidites, Cicatricosisporites, and smooth triangular trilete spores of Cyatheaceae that are characteristic of the Patuxent-Arundel succession (Zone I) (?Barremian–Aptian) in Maryland. McLaughlin (this study) additionally reports very small (12 µm) faintly reticulate tricolpoiroidate angiosperm pollen (aff. Tricolpites albiensis) and another small angiosperm pollen similar to Retitricolpites virgius in these two samples, suggesting assignment to Subzone IIB (Albian). Assignment to Subzone IIB is consistent with log correlations that suggest the 599.3 ft (182.67 m) level at Fort Mott should correspond to ~515 ft (156.97 m) in Dc53-07 to ~590 ft (179.83 m) or so at Ec14-01 in Delaware, both of which were recognized as Subzone IIB by Doyle and Robbins (1977). The sample at 806.0 ft (245.7 m) is placed in Zone I (Aptian).