Sixteen samples from the Medford corehole were analyzed by G. Brenner for pollen, as well as spores (Table T3) ranging in age from Turonian to lower Cretaceous (Albian–Barremian). Thirty-four additional samples plus ten of Brenner's samples were later reanalyzed by P. McLaughlin to further refine Brenner's biozonation. Most of the samples yielded meager spore and pollen preservation, and many samples were essentially barren. Stratigraphically diagnostic forms were generally absent. Samples are assigned ages using the zonations of Brenner (1963) and Doyle and Robbins (1977).
The Cheesequake Formation contained only rare pollen that could not be zoned. Samples between 471 and 560 ft (142.7 and 169.7 m) (essentially all of the Magothy Formation) contain a poorly preserved flora assigned by Brenner to Zone V (Turonian to Coniacian). McLaughlin notes the presence of some older forms at 529, 560, and 561.8 ft (160.3, 169.7, and 170.2 m) that are found commonly in Zones IV and III; the latter sample is provisionally assigned to undifferentiated III–IV (Cenomanian). Samples at 522.4 and 562 ft (158.3 and 170.3 m) contain dinoflagellates, indicating marine conditions for the material assigned to the Amboy Stoneware Clay and the South Amboy Fire Clay.
The Raritan Formation and Potomac Formation Unit III are assigned to Zone III (Cenomanian). Samples at 581 and 585 ft (227.7 and 177.3 m) contain specimens of Apiculatisporis babsae and Neoraistrickia robustus normally confined to Zone II. This would make the Raritan Formation much older (middle Albian) than at other localities (middle Cenomanian to lower Turonian) and these specimens are assumed to be reworked by Brenner. McLaughlin notes numerous finely reticulate tricolpates and small tricolp/tricolporates with slightly thickened rims, possible Tricolpites nemejcii (the only marker present for Zone III or higher) and no triporates, normapolles, or other advanced angiosperms indicative of Zone IV; he thus assigns samples from 610, 628.5, and 660.7 ft (184.8, 190.5, and 200.2 m) to Zone III. However, Brenner, based on the presence of R. multilex, assigns the sample at 677.8 ft (205.4 m) to Zone IV. It is hard to reconcile these data. Zone IV is very unusual for the Potomac Formation, which is Zones I–III, and it is assumed that the identification of Rugibivesiculites multilex is incorrect because of poor preservation or contamination.
Poor preservation prevents the confident distinction between Zones IIC (upper Albian) from III (lower Cenomanian). Samples from 709.5 and 752.0 ft (215 and 227.9 m) are assigned to Zone III. A sample from 761.1 ft (230.6 m) could be assigned to either Zones IIC or III. The lack of definitive Zone III forms may indicate IIC is more likely. Samples from 933.8, 942.5, and 982.2 ft (283, 285.6, and 297.6 m) are assigned to Zone IIB. The sample from 893.4 ft (179.8 m) is Zone IIB (middle Albian) or younger. Other samples between 761.1 and 933.8 ft (230.6 and 283 m) were barren, and thus the Zone IIC/IIB boundary is difficult to place. Two samples from near the bottom of the hole contain common occurrences of species of Schizaeaceae spores more typical of Zone I lowermost Albian to Aptian/Barremian) than Zone IIA (lower Albian).
Planktonic foraminifers were only analyzed to identify the location of the Cretaceous/Paleogene boundary (Table T4) that was identified between samples from 57.4 and 57.5 ft (17.5 and 17.53 m) and 61.4 and 61.5 ft (18.71 and 18.75 m). The zonal scheme used below is that of Berggren et al. (1995). The uppermost samples from 55.4 to 55.5 ft (16.89 to 16.92 m) and 56.1 to 56.2 ft (17.1 to 17.13 m) are assigned to Zone P3a based on the occurrence of Acarinina strabocella, Globanomalina compressa, and Morozovella angulata.
The interval from 57.4 to 57.5 ft (17.5 to 17.53 m) is assigned to Zone P1c and contains the following planktonic species diagnostic of this zone: Subbotina triloculinoides, Parasubbotina pseudobulloides, G. compressa, Globoconusa daubjergensis, Praemurica inconstans, Praemurica pseudoinconstans, and Chiloguembelina midwayensis.
The first Maastrichtian foraminifers are encountered at 61.4–61.5 ft (18.71–18.75 m), indicating that the K/P boundary occurs between this sample and the one above. Although the sample can be placed in the Maastrichtian, no zonal species occur, probably because of the shallow environment of deposition. Maastrichtian foraminifers include Heterohelix globulosa, Guembelitria cretacea, Rugoglobigerina reicheli, Rugoglobigerina rugosa, and Globigerinelloides multispina.
The calcareous nannoplankton biozonal subdivision of the Cenozoic section of the corehole provided surprisingly good results considering how thin and shallow the Cenozoic section is at the Medford site (Table T5). The upper three samples down to 11 ft (3.4 m) were barren because of secondary silicification. However, except for the sample at 60.6 ft (18.5 m) that contained rare coccoliths, the remainder of the samples contained common to abundant, well to moderately preserved calcareous nannofossils. The zonal scheme used below is that of Martini (1971) and Martini and Müller (1986).
The sample from 33.0 ft (10.1 m) is assigned to Zone NN8 based in the occurrence of Heliolithus riedelii and Discoaster mohleri. The sample from 41 ft (12.5 m) is tentatively assigned to Zone NP7 because of the occurrence of D. mohleri. Zone NP7 is more definitively assigned to the sample at 48 ft (14.6 m) based on the co-occurrence of Fasciculithus tympaniformis, Heliolithus kleinpelli, and D. mohleri. The dominance of pentatiths of Braarudosphaera spp. and Micrantholithis spp. at 41 ft (12.5 m) may be related to shallowing that is supported by is position above the MFS of the Pa2b sequence.
There is a clear stratigraphic gap between the sample at 48 ft (14.6 m; Zone NP7) and the next lower sample at 55.5 ft (16.9 m) with a hiatus of ~3 m.y. This supports the placement of a sequence boundary at 50 ft (15.2 m) placed within an interval of no recovery. The samples from 55.5, 57.0, 57.25, 57.7, and 60.1 ft (16.9, 17.4, 17.45, 17.6, and 18.3 m) are all assigned to the lower part of Zone NN4 based on the co-occurrence of Chiasmolithus danicus, Cruciplacolithus tenuis, and Ellipsolithus macellus.
A sample at 60.6 ft (18.47 m) just above the K/P boundary (60.7 ft; 18.5 m) contained rare poorly preserved coccoliths with Chiasmolithus danicus and Cruciplacolithus danicus. It is assigned at a minimum to Zone NP3, although lower NP4 cannot be ruled out. This sample also contained reworked Cretaceous coccoliths from below the K/P boundary. The sample from 72 ft (18.5 m) contained abundant Cretaceous species with Arkhangelskiella cymbiformis, Eiffeillithus turriseiffelii, Micula spp., Watznaueria barnesae, and rare Danian species (assigned to Subzone NP1b), indicating mixing of younger species from above.
We obtained 19 initial samples from the Medford corehole that were studied by Bukry for Cretaceous calcareous nannofossils (Table T6). Ten of these samples contain calcareous nannofossils and could be zoned; the other nine samples were barren. An additional 43 samples (19 barren) focusing on the biostratigraphy of the Merchantville sequences were studied by Mizintseva (Table T6). Cretaceous calcareous nannofossils were locally abundant, although there were many barren samples. The nannofossil zonation and CC terminology of Sissingh (1977) were used to subdivide the section.
Samples from 61 and 76 ft (18.6 and 23.2 m) in the Navesink II sequence are assigned to Zone CC26, although there was abundant mixing of Paleocene forms in the 61 ft sample (18.6 m). A sample from 96 ft (29.3 m) in the Navesink I sequence is assigned to Zone CC25c or CC25b.
Three samples from the Marshalltown sequence are assigned to Zone CC21–CC22 (176 ft; 53.6 m) and Zone CC20 (206 and 21 ft; 62.8 and 67.4 m). Rare specimens in two samples (266 and 301 ft; 81.1 and 91.7 m) from the upper Englishtown Formation are assigned to Zone CC20 and Zone CC18–CC20.
The top of sequence MeIII (331 ft; 100.9 m; top of the lower Englishtown Formation) is assigned to Zone CC20. The middle of sequence MeIII (341–381 ft; 103.9–116.1 m; basal lower Englishtown, Woodbury, and upper Merchantville Formations) is assigned to Zone CC19. The base of sequence MeIII (386 ft; 117.7 m; Merchantville Formation) is assigned to Zone CC18. The top of Sequence MeII (390–404 ft; 118.9–123.1 m; Merchantville Formation) is assigned to Zone CC17. The bottom of sequence MeII (413 ft; 125.9 m; Merchantville Formation) is assigned to Zone CC16. Sequence MeI (423–425 ft; 1128.9–129.5 m; Merchantville Formation) is assigned to Zone CC16. All samples below the Merchantville Formation were barren for calcareous nannofossils.