Geologic Map of Offshore Delaware
Date
2020-02
Journal Title
Journal ISSN
Volume Title
Publisher
Newark, DE: Delaware Geological Survey, University of Delaware
Abstract
Delineation of map units is based on sediment-core descriptions (e.g., texture, color, and composition) from 469 locations and seafloor morphology, which was assessed from a seamless NOAA/USGS topo-bathymetric model (Pendleton et al., 2014). The latter was integrated with high-resolution ‘chirper’ seismic reflection data, collected in 2013 by the Delaware Division of Natural Resources and Environmental Conservation (DNREC) and in 2015 as part of the 2015-2017 Bureau of Ocean Energy Management (BOEM) Atlantic Sand Assessment Project (ASAP), using sweep frequency pulses of 2-12 kHz and 0.7-12 kHz, respectively. Stratigraphic mapping based on these data allowed seafloor composition to be inferred across areas of limited core coverage (e.g., Federal waters, beyond 3 miles from shore) and facilitated the delineation of unit boundaries based on subsurface trends and seafloor geomorphology. A minimum surface-unit thickness of 1 ft served as the cut-off for geologic mapping of the seafloor, given the vertical resolution constraints of geophysical data. If surficial sediments were <1 ft thick, the underlying unit was mapped. Unit names and descriptions conform to those established in prior subsurface work along the Delaware barrier shoreline by Ramsey (1999), a synthesis of the Delaware coastal plain geology (Ramsey, 2010), and a previous map which included portions of the offshore surface geology (Ramsey and Tomlinson, 2012).
Description
Keywords
Cenozoic Era, Quaternary Period, Holocene, upper Holocene, lower Holocene, Pleistocene, upper Pleistocene, middle Pleistocene, lower Pleistocene, Tertiary Period, nearshore deposits, finger shoal deposits, sheet sand deposits, Inter-Shoal deposits, Ebb-Tide Delta Sand deposits, lagoon deposits, Ravinement Lag Deposits, Sinepuxent Formation, Marine Shelf Deposits, Lynch Heights Formation, Omar Formation, Beaverdam Formation, offshore, sand resources, Delaware, Sussex County, Rehoboth Beach, Dewey Beach, Cape Henlopen, Bethany Beach, Fenwick Island, Lewes