Abstract

The four separate sites of the Chesapeake Bay National Estuarine Research Reserve in Virginia are within the Coastal Plain province of the mid-Atlantic. The surficial geology at each site is of Quaternary age, primarily Holocene wetlands. The site at Taskinas Creek is set into Tertiary age strata. The underlying strata increase in age up-stream. Regionally, the Late Tertiary and Quaternary geology is a function of the series of major transgressions and regressions, during which the successively more recent high stands of sea level generally have not reached the level of the preceding high stand. As a consequence, stratigraphically higher, younger deposits occur topographically below exposures of the older strata. The two down-stream reserve sites are within the area of the Eocene age Chesapeake Bay Impact Crater. Also at these two sites, the tidal marshes are superimposed on a ridge and swale topography. The local rate of sea-level rise, approximately 4 mm/yr, is the underlying process driving changes to the tidal marshes at all four sites. The Goodwin Islands, at the mouth of the York River with exposure to Chesapeake Bay, can be severely impacted by storm waves and surge. Future research should include a program ofcoring to develop the time-history of recent rise of sea level and assist on-going efforts toward mapping the regional geology and toward understanding the local and regional ground-water systems.In addition, establishment of permanent benchmarks to document elevation would enable long-term monitoring of subsidence and facilitate differentiation of the eustatic and isostatic components of changes in relative sea-level rise relative to climate change or other factors.

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