Mattheus, C.R.Ramsey, K.W.Tomlinson, J.L.2020-03-252020-03-252020-02http://udspace.udel.edu/handle/19716/25112Delineation 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).en-USCenozoic EraQuaternary PeriodHoloceneupper Holocenelower HolocenePleistoceneupper Pleistocenemiddle Pleistocenelower PleistoceneTertiary Periodnearshore depositsfinger shoal depositssheet sand depositsInter-Shoal depositsEbb-Tide Delta Sand depositslagoon depositsRavinement Lag DepositsSinepuxent FormationMarine Shelf DepositsLynch Heights FormationOmar FormationBeaverdam Formationoffshoresand resourcesDelawareSussex CountyRehoboth BeachDewey BeachCape HenlopenBethany BeachFenwick IslandLewesMap