45 Past, Present, and Future Sea-level and Landscape Change on the U.S. Coast and Continental Shelf

Tuesday, 16 April 2024
1:30 PM - 5:30 PM
Swannanoa

EVOLUTION OF SEDIMENTATION PATTERNS AND LOCAL RATE OF HOLOCENE SUBSIDENCE AT CAPE HENRY (VIRGINIA) REVEALED FROM LUMINESCENCE AGES OF BEACH RIDGES

Paper number: 45-4
Program: Theme Sessions
Time: 2:30 PM – 2:50 PM

Authors

Abstract

A large beach ridge complex at Cape Henry (Virginia) aggraded into the mouth of the Chesapeake Bay during the past 5000 years. Seven recently collected luminescence ages combined with detailed Lidar mapping permit reevaluation of previous studies into the stratigraphy and geomorphic evolution of the complex. Near the scarp bordering the southern edge of the complex OSL analyses of the oldest ridge sediments indicate an age of 4999+290 years; the OSL age on sediment from the youngest dated ridge, 800 m from the present (accreting) shore, is 1030+70 years. Analyses based on all seven ridge ages and varying ridge morphologies across the complex suggest the area grew relatively steadily with episodes of localized shoreline stability; periods of shoreline retreat appear to be rarely substantial or extensive. Ridge patterns also suggest that the gradual northeastern-to-northern growth of the cape slowed markedly and veered to the northwest approximately 2000 years ago, perhaps as an hypothesized sediment-source headland to the southeast diminished. Prior studies noted that relatively coarse foreshore deposits lie at depth across the study area. Analyses using the basal elevation of that facies near the dated ridges suggest that the local average long-term subsidence rate due to glacio-isostatic adjustments was approximately 2 mm/year during the mid-late Holocene.

Geological Society of America Abstracts with Programs. Vol. 56, No. 2

doi: 10.1130/abs/2024SE-398519

© Copyright 2024 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.