J.J. Groot

Some observations on pollen grains in suspension in the estuary of the Delaware River

Abstract Pollen spectra of samples or suspended and bottom sediments in the Delaware River estuary represent the regional vegetation of the Basin as a whole rather than local plant communities. There appears to be a relationship between the number of pollen grains and the quantity of mineral matter in suspension, suggesting that the two types of particles are transported together and in similar fashion, that is, by water currents primarily.

Palynological evidence for late miocene, pliocene and early pleistocene climate changes in the middle U.S. Atlantic Coastal Plain

Abstract Palynomorph assemblages from eight geologic formations in the Middle Atlantic Coastal Plain, ranging in age from latest Miocene to Early Pleistocene, have been interpreted in terms of terrestrial paleoclimates. The data suggest that a warm-temperate to subtropical climate, warmer than at present, prevailed at the close of the Miocene and the beginning of the Pliocene. At that time, there was little or no temperature gradient within the study area (36°30′ to 39°N). This warm period was followed by a warm-temperate interval in Virginia and North Carolina, with temperatures probably not very different from those of today, although a slight warming trend probably occurred during the deposition of the Colerain Beach Member of the Chowan River Formation. A definite cool interval is indicated by the presence of spruce pollen in the Bacons Castle Formation of Virginia. This interval is interpreted to have begun about 2.3–2.4 Ma, or possibly slightly later, simultaneous with the cooling that has been recorded in deep-sea cores of the North Atlantic Ocean, and in the pre-Tiglian of western Europe. This was followed by a warmer-than-present period that may be correlated with the Tiglian of the latest Pliocene. Finally, palynological data from the Cape May Formation of New Jersey suggest that a warm-temperate (warmer than at present) climate prevailed during the Early Pleistocene.

Palynological, foraminiferal and aminostratigraphic studies of quaternary sediments from the U.S. middle Atlantic upper continental slope, continental shelf and coastal plain

Abstract A pollen climate index curve provides the basic stratigraphic subdivision of the 305 m cored Quaternary section of AMCOR 6021C located on the upper continental slope off New Jersey, U.S.A. Cold and warm intervals from top to bottom were assigned to Marine Oxygen Isotope Stages 1 through 13(?). At a sub-bottom depth of about 220 m, foraminiferal data indicate a possible hiatus, and, if so, sediments below this may be as old as Isotope Stage 16 or older. Aminostratigraphic studies yielded results that are consistent with either interpretation. Benthic foraminifers are dominated by Elphidium excavatum and Islandiella norcrossi . The planktic foraminiferal record provided no independent means of subdividing the section. The stratigraphic distribution in 6021C of six species of Quercus (oak) and aminozone determinations were applied to dating, in terms of presumed Oxygen Isotope Stages, of other offshore core hole samples and some onshore Quaternary deposits of Delaware. Stratigraphic information from AMCOR sites 6021 and 6009 correlated to seismic reflection profiles that cross the shelf/slope break indicate that the thickest accumulations of terrigenous Quaternary sediments are located along the outer continental shelf/upper continental slope offshore the northeastern United States.

Palynological Investigation of a Core from the Biscay Abyssal Plain

An investigation of Quaternary, Tertiary, Mesozoic, and Paleozoic pollen and spores found in sediments of the Biscay Abyssal Plain provides data leading to the interpretation of the provenance of the lutite in which reworked plant microfossils occur. Owing to the difficulty of distinguish(Ag between Quaternary and reworked Tertiary pollen grains belonging to extant genera, caution is necessary in interpreting the pollen record in terms of Quaternary climatic changes.