This file was generated to illustrate sediment-facies distributions across the inner continental shelf of Delaware. It delineates surface geologic units mapped from core information housed with the Delaware Geological Survey (DGS), seafloor topography (2015 USGS/NOAA dataset), and seismic subsurface reflection imagery (BOEM dataset collected by CB&I in 2015). This product represents the "current thinking" of the DGS staff regarding the surficial geology of the Delaware shelf. This product is explained in detail in DGS product ‘Geologic Map of Offshore Delaware’ (Geologic Map Series 25), by Mattheus et al. (2020). Surface geologic units have been mapped across the inner continental shelf off Delaware, from the shoreline to ~10 miles from shore (Federal waters). The coverage area spans from the Hen and Chickens Shoal (in the north) to the Fenwick Shoal (in the south). Mapping relied on lithologic descriptions of the surface interval (defined as the upper foot in core) from over 450 DGS offshore sediment cores. This dataset was supplemented with high-resolution sub-surface 'chirper' seismic reflection imagery and 2007 hydrographic data (USGS/NOAA). Seafloor topography was useful in the delineation process as it provided information on the bounds and extents of respective geologic map units sampled in core. These units are as follows, established based on textural criteria, color, fossil content, and correlation to established onshore geologic units (Ramsey, 2010): Qets = ebb-tidal delta sand deposits affiliated with the Indian River Inlet, Qns = nearshore deposits, Qfs = finger shoal deposits (shore-attached and shore-oblique), Qsl = shoal deposits (affiliated with the Hen and Chickens sand body), Qss = sheet sand deposits, Qis = inter-shoal deposits (generally found surrounding the distal end of the Hen and Chickens Shoal), Ql = lagoonal deposits, Qrl = ravinement lag deposits, Qms = Marine shelf deposits (which form a SE-ward thickening wedge within the southern portion of the DE shelf), Qlh = Lynch Heights Formation (a Pleistocene bay-margin deposit), Qsi = Sinepuxent Formation (a Pleistocene lagoonal unit), Qo = Omar Formation (a mid-Pleistocene, muddy to sandy valley fill deposit), and Tbd = Beaverdam Formation (late Pliocene to early Pleistocene fluvio-deltaic sediments).
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