21 Current Research in Coastal and Nearshore Processes (Posters)

Sunday, 20 March 2022
1:30 PM - 5:30 PM
Freedom Hall A

INVESTIGATION OF LATE PLEISTOCENE-HOLOCENE POLLEN ASSEMBLAGES FROM THE UPPER NASSAWADOX FORMATION AND ASSOCIATED PALEOSOL, SAVAGE NECK DUNES STATE NATURAL AREA PRESERVE, EASTERN SHORE, VIRGINIA

Paper number: 21-3
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Recent investigation of pollen extracted from an exposure at Savage Neck Dunes (SND) has yielded a new and expanding database that provides potential for a quantitative analysis of Pleistocene-Holocene environmental change in this region (Points & Cornell, 2021). Previous authors identified a number of units at the study site. Davis (2020) mapped 3 units in the succession from SND to Latimer's Bluff. Units 1 and 2 are exposed at SND. The lowest (unit 3) is developed below the paleosol (unit 2) at Butler's Bluff and is not exposed at our study site. The exposed units at SND include the middle and upper Nassawadox Fm (Butler's Bluff & Occohannock mbrs). The paleosol (unit 2 of Davis) is not well understood because of poor exposure beneath unconsolidated sands of unit 1. Nevertheless, the paleosol is significant as it has been documented to underlie Clovis-age artifacts and is mapped as part of a wider complex of loess deposits on the Eastern Shore (Lowery et al, 2010). Lowery and colleagues have interpreted 2 loess deposits, the lowest (Miles Point) has a well-developed paleosol known as the Tilghman Paleosol in the northern Delmarva. The lowest loess has been age dated to MIS 3 (late Wisconsinan) and may be as old as 60,000 kya, and the upper loess deposit (Paw Paw) was deposited during the Younger Dryas (early MIS 1). The paleosol at SND is not sufficiently dated to either of these loess deposits.

This study recognizes 7 distinct horizons below unit 1 of Davis (2020). Five are within the paleosol, and 2 horizons (a peat and freshwater underclay) lie below it. Initial pollen isolates have yielded communities composed of arboreal and non-arboreal taxa (i.e. grasses). Presence of previously unrecognized cool-temperate taxa, not represented in the modern forest at SND, and a horizon with grass taxa points to dramatic climate oscillations before the modern assemblage is established. Webb et al (1993) document changes in arboreal pollen and associated climate changes in Eastern North America from 18kya to present. Our developing dataset seeks to: 1) further refine the pollen assemblages at SND, 2) relate the SND pollen assemblages to regional models of Webb et al. 3) enhance the resolution of the timeline of environmental changes in the greater Chesapeake Bay region, and 4) improve the timescale for the study of paleo-Indian artifacts at SND.

Geological Society of America Abstracts with Programs. Vol. 54, No. 3

doi: 10.1130/abs/2022NE-374934

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.