Geologic Map of the Elkton, Saint Georges, and Delaware City Quadrangles, Delaware
Date
2023-05
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Publisher
Newark, DE: Delaware Geological Survey, University of Delaware
Abstract
Geologic mapping was conducted at 1:12,000 with a 1-ft contour basemap. In some instances, stratigraphic boundaries drawn at topographic breaks reflect detailed mapping using LiDAR data. Elevations of stratigraphic contacts along stream valleys are projected from subsurface data. Except for a few erosional bluffs, these contacts are covered by colluvium. This map supersedes this portion of Geology of the Chesapeake and Delaware Canal Area, Delaware: Delaware Geological Survey Geologic Map Series No. 1 (Pickett, 1970) and Geologic Map of New Castle County, Delaware: Delaware Geological Survey Geologic Map Series No. 13 (Ramsey, 2005).
The geological history of the surficial units of the Elkton, Saint Georges, and Delaware City Quadrangles is the result of erosion of the Potomac Formation and younger Cretaceous and Cenozoic units by glacial dam burst events during the early Pleistocene. These periods of erosion were followed by stream incision and fluvial and estuarine deposition associated with multiple sea-level fluctuations during the middle to late Pleistocene. Periglacial activity that followed produced Carolina Bay deposits, alluvium along stream valley slopes, and freeze-thaw features on the land surface.
Description
Keywords
Cenozoic Era, Quaternary Period, Holocene, Pleistocene, Pliocene, Miocene, Paleocene, Cretaceous Period, Upper Cretaceous, Lower Cretaceous, Scotts Corners Formation, Lynch Heights Formation, Columbia Formation, Beaverdam Formation, Matawan Formation, Potomac Group, Navesink Formation, Hornerstown Formation, Mount Laurel Formation, Marshalltown Formation, Englishtown Formation, Merchantville Formation, Carolina Bay deposits, sand, clay, deposits, marsh deposits, swamp deposits, modified land, fill, Carolina bays, Glauconite, Delaware, New Castle County