22 Interstate Stratigraphic Correlation: A Practical Geology Session

Primarily a hands-on display of core and samples with posters, and talks, to facilitate interstate correlation. Concepts covered are related to interstate correlation problems in stratigraphy—mapping, source rocks for REE minerals, geochronology, and regolith.

Tuesday, 10 March 2026
10:30 AM - 12:00 PM
RCC, 103

Stratigraphic Correlation of Late-Pleistocene Geologic Units along the Dlemarva Peninsula and Beyond

Paper number: 22-0
Program: Technical Sessions
Time: 10:30 AM – 10:50 AM

Authors

Abstract

The US Atlantic Coastal Plain includes coastal deposits which were emplaced during sequential relative sea-level highstands during the late Quaternary. As such, the sedimentology, stratigraphy, and morphology of these deposits retain a record of past marine transgressions during which water levels reached elevations equal to or higher than today. Investigating these geologic units provides information regarding the sea level history, and the potential rate and magnitude of sea-level forcing mechanisms, ultimately allowing for a more complete understanding of potential risks and hazards of climate change today. However, these investigations are hindered due to differing nomenclature and interpretations of mappable geologic units across state borders. This issue can be resolved through interstate geologic and stratigraphic correlations of lithologic units emplaced during the most recent marine transgressions during the late-Pleistocene (~125–30,000 years ago).

Recently, quadrangle-scale (1:24,000) geologic mapping in the Virginia Eastern Shore (VES) and Delaware (Del.), in conjunction with legacy geologic maps from the Maryland Eastern Shore (MES)—a region collectively referred to as the Delmarva Peninsula—allow for cross-state stratigraphic correlation of the geologic formation emplaced during marine isotope stage (MIS) 5a (~90–70,000 years ago) the last time relative sea-level was higher than today. The Locustville Member (Mbr.) (VES) lies at an elevation of 2–4 meters, contains beach-and-foredune ridges, and is composed of lagoon, beach, and nearshore deposits with characteristically high proportions of mica and Mulinia spp. The depositional environments, elevation, morphology, and lithology of the Locustville are nearly identical to those of the Sinepuxent Formation (Fm.) in Del. and MES. Furthermore, the absolute ages of the Sinepuxent Fm. and Locustville Mbr. also align at ~80,000 years. As such, we determine that these two geologic units are coeval.

Comparing the lithology, morphology, and age of the MIS 5a deposit in the Delmarva Peninsula to mapped geologic units in southeastern Virginia and northeastern North Carolina, we propose that this unit is likely coeval with the Poquoson Mbr. (Tabb Fm.) and may extend further south into South Carolina. These findings and hypotheses present an opportunity for a broader understanding of past sea-level change and associated depositional/erosional processes at larger spatial scales.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411757

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