23 Current Research in Coastal and Nearshore Processes (Posters)

Monday, 18 March 2024
9:00 AM - 1:00 PM
Armory Ballroom

DETAILED MICRO AND MACRO-FOSSIL ANALYSES OF VIBRACORES FROM CUSTIS POND, SAVAGE NECK DUNES NATURAL AREA PRESERVE (SNDP), EASTERN SHORE, VIRGINIA REVEAL LATE PLEISTOCENE-HOLOCENE ENVIRONMENTAL CHANGE IN THE LOWER CHESAPEAKE BAY

Paper number: 23-4
Program: Theme Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

Recent studies put local SLR along the coasts of the Delmarva Peninsula at 3-4 times the global average, making this region highly vulnerable. At SNDP, located on the Chesapeake Bay, the rapidly eroding shoreline exposes layers of the late Pleistocene Tilghman paleosol which is overlain by large, Holocene sand dunes and threatens a diverse maritime forest and freshwater bogs and ponds. Custis Pond, located just east of the shoreline, contains a sedimentary record of environmental change likely resulting from sea level changes since the last glacial maximum, ~20K years ago. This study aims to determine the depositional environments represented by sediments obtained from 5, 1-4 m-long vibracores extracted from the pond in 2021-2022. Core analyses include loss on ignition for organics taken at 5 cm intervals, grain size, micro and macro-fossil ID, and detailed core descriptions. We use these analyses to divide the core into facies representing different depositional environments: paleosol, paleodune, paleovalley, and pond (in superposition order). For this project, we focused on the identification of the macro-and microflora and fauna contained in each facies for better environmental control. The modern freshwater pond is surrounded by maritime forest and is characterized by stagnant waters populated by duckweed. Pollen analysis of the paleosol exposed on the beach suggests the region experienced a change from cool to warm temperate conditions following the LGM. We will compare the paleosol sampled at the bottom of VC5 to the paleosol found along the shoreline. Preliminary analysis indicates the presence of a native sedge plant Whip Nutrush (Scleria triglomerata) described in this region in 1935. These data, combined with core analysis, GPR data, historical records, and radiocarbon dating to provide age control for the cores, will allow us to determine environmental changes that occurred in SNDP since LGM and add to the broader understanding of the impacts of climate change and SLR in this region.

Geological Society of America Abstracts with Programs. Vol. 56, No. 1

doi: 10.1130/abs/2024NE-397763

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