THE PALYNOLOGY OF THE UPPER CRETACEOUS RARITAN FORMATION
plant fragments. Bedding is not visible in the sediment samples, and cementa- tion is absent. Sediment samples dem- onstrate that the base of the Lloyd Sand is unconformable with the weathered bedrock and the bedrock. The fine sand layers at the top of the formation grade quickly into the Raritan Clay.
At the locations of borings XB-2 and IT-045D (Figure 2), 21m-thick distribu- tary channel sands are present which grade upward from a very coarse con- glomeratic sand to predominantly very fine to fine sand. The Lloyd Sand in the study area has been interpreted by the author as having been deposited as point bars in distributary channels and meander belts in a deltaic environment.
Raritan Clay - Lower Unit
The typical thickness of the lower unit of the Raritan Clay in the study area ranges from 0 to 13.8 m (Figures 3 and 4). The formation is predominantly light to olive gray with moderate red- brown mottling. The mottling varies from irregular ovals several millimeters in length to streaks slightly longer than
one centimeter. In the Raritan, NJ area to the southwest, the red-brown mottling is visible in the sidewalls of the clay pits and is only present where the clay is directly overlain by a thin ironstone layer. The clay is dense to very dense and becomes dry at depth. The sediment samples are very thinly bedded and plasticity for the unit is generally high.
As represented by the filled black circles in Figures 3 and 4, river channel sands are incised into the clay from loca- tions IT-305 to D12 and from IT-044I to IT-005. The thickness of the distributary channel sands averages 13.5 m, but reaches 14.5 m thick at GW-29 (Figure 3). At locations IT-511 and IT-044I (Figure 2) the lower clay unit has been interpreted as residing in a slumped river channel. The slumped sediments may have originated as the result of sedi- ment consolidation landslides, glacio- isostatic deformation, or possibly due to an episode of seismic activity.
Raritan Clay - Upper Unit
Figure 3 depicts that the upper unit is complexly interbedded with the lower
unit under the Fresh Kills Landfill, and is 0-14.1 m thick, varying in color from olive gray to olive black. Bedding is very thin and silt content is moderate to high, with very fine to fine sand pres- ent in pockets and as laminae. Mica is uncommon to common, plant fragments are absent to common, and iron sulfide nodules are occasionally present. The sediment samples are stiff and dense, plasticity is slight to moderate and dilat- ancy is slight to moderate when moist, though moisture content is generally low. Lignite laminae from less than one millimeter to a few millimeters thick and lignite interbeds are common at various locations. Sulfurous odors are apparent with freshly opened soil cores. Thin interbedded layers of sand with very fine to fine sand grains are present in the upper unit from IT-307 to GW-29 (Figure 3) and a thicker lenticular body of sand is present at the location of boring O-20.
The depositional environment for the entire Raritan Clay within the study area has been interpreted by the author as either the interdistributary bay or an upland restricted deltaic environment such as a floodplain containing swamps or marshes.
Figure 3. Lloyd Sand and Raritan Clay
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