GSA Connects 2021 in Portland, Oregon

Paper No. 92-5
Presentation Time: 9:00 AM-1:00 PM


POINTS, Elisabeth and CORNELL, Sean R., Department of Geography and Earth Science, Shippensburg University, 1871 Old Main Drive, Shippensburg, PA 17257

Recent erosion in Savage Neck Dunes State Natural Area Preserve has exposed a paleosol. The top of the paleosol is approximately two feet above mean high tide level and contains a ghost forest buried by dunes above. Recent work has suggested that the eolian succession may be younger than 1,100 B.P. Other researchers have suggested a late Pleistocene age for the same dune succession. The age of the paleosol is controversial and may be a composited paleosol that may be older than 13,000 B.P. The lowest unit is an indurated, clay-rich mud that is now exposed within the intertidal zone. Between the paleosol and underclay is an organic peat composed of pine needles, pine cones, and other woody debris which was buried by two feet of sandy silt interpreted by Wah et al. 2018 as Wisconsinan loess.

This study investigates the paleosol as well as the peat horizon for palynological evidence. Thirteen samples of the composited (?) paleosol were taken for radiocarbon dating and environmental analysis. The study is ongoing at this writing and preliminary data will be reported. However, the succession above/below the paleosol reveal a more complicated sea level history and environmental changes than reported for this site. The underclay, a marine sediment, was uplifted above sea level to accumulate enough organic matter to produce approximately one foot of detritus that included evident woody tissues. This was subsequently buried and compacted by windblown loess and then developed into one, if not two, paleosol horizons (see Wah et al. 2018). To complicate the story even more, the paleosol complex developed yet another forested horizon that was engulfed in the sand, and is now being re-exposed by modern erosion.

In addition to the pollen analysis, this study involves mapping the distribution of upright trees in the paleosol using both historical imagery and GPS logging of recently exposed trees. A total of 74 trees have been GPS logged in the field, and 43 additional trees were mapped using historical photos along a transect of over 400 meters. The documentation of this site using palynological and mapping techniques to uncover a more detailed timeline of sea level changes as well as paleoenvironmental conditions for this area will contribute to a more refined understanding of not only Savage Neck Dunes, but also to the broader Delmarva region.