DGS Bulletins
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Browsing DGS Bulletins by Author "Groot, J.J."
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Item Engineering Materials Of Northern New Castle County(Newark, DE: Delaware Geological Survey, University of Delaware, 1957-11) Ward, R.F.; Groot, J.J.This investigation was undertaken to locate deposits of rock, sand, gravel, fill and borrow in northern New Castle County which may be potential sources of material for highway construction, and to prepare maps and descriptions of the surficial earth materials relative to their geologic and engineering properties.Item Geology and Ground-Water Resources of the Newark Area, Delaware with a section on the Surface Water Resources(Newark, DE: Delaware Geological Survey, University of Delaware, 1954-04) Groot, J.J.; Rasmussen, W.C.; Hulme, A.E.This report describes the geological and lithological conditions in the Newark area, and the occurrence, quantity, and quality of the available ground-water supply. Newark is located on the Fall Line, the boundary between the rolling hills of the Piedmont on the north and the gentle slopes of the Coastal Plain on the south. Because the Piedmont is underlain by dense crystalline rocks and their weathered clayey soils, which are of low water-bearing capacity in contrast to the more permeable silts and sands of the Coastal Plain, the exploration for ground water was confined to the Coastal Plain south and southeast of Newark.Item Marine upper cretaceous formations of the Chesapeake and Delaware Canal(Newark, DE: Delaware Geological Survey, University of Delaware, 1954-11) Organist, D.M.; Richards, H.G.; Groot, J.J.In the Coastal Plain of Delaware, the non-marine Cretaceous sands and clays are separated from the Tertiary formations by a series of marine formations of Upper Cretaceous age. The sedimentary and hydrologic characteristics of these formations deserve detailed study because some of them are water-bearing beds. whereas others act as confining beds. A clear understanding of their relative age. and the presence or absence of unconformities is needed for proper correlation with formations found in wells throughout the State. as well as in Maryland and New Jersey.Item Sedimentary Petrology Of The Cretaceous Sediments Of Northern Delaware In Relation To Paleogeographic Problems(Newark, DE: Delaware Geological Survey, University of Delaware, 1955-07) Groot, J.J.The non-marine Cretaceous sediments of northern Delaware older than the Magothy formation cannot be divided accurately into formations or mappable geologic units because their lithologic characteristics are very similar. However, two heavy mineral zones can be distinguished in these deposits: a lower staurolite-kyanite-tourmaline-zircon zone, and an upper tourmaline-zircon-rutile zone with abundant alterites. They have been named the Patuxent zone and the Patapsco-Raritan zone respectively. The Magothy formation is characterized by abundant staurolite and also contains significant amounts of tourmaline. The marine Upper Cretaceous deposits have a greater variety of heavy minerals than the underlying non-marine sediments. They contain abundant epidote; chloritoid, first appearing at the base of the Merchantville formation, is persistently present. Garnet is found in the Merchantville and the Mount Laurel-Navesink formations. The heavy mineral composition of the Cretaceous sediments is shown in table IV.Item The Water Resources Of Northern Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1957-06) Rasmussen, W.C.; Groot, J.J.; Martin, R.O.R.; McCarren, E.F.; Behn, V.C.Northern Delaware, the area above the Chesapeake and Delaware Canal in New Castle County, is an area of rapidly growing population and expanding industry. In some places the demand for water has reached or exceeded the capacity of the existing facilities creating apparent water shortages. Many agencies, both public and private, are attempting to alleviate these shortages; studies are being made and reports prepared for immediate action as well as long-term planning. It is the purpose of this report to examine on a long-range basis the water resources of the northern Delaware area. This examination indicates that the surface-water and groundwater resources of the area far exceed the 72.8mgd (million gallons per day) used during 1955. The amount of ground water potentially available in the area is estimated to be at least 30 mgd and the amount of surface water potentially available depends principally on the amount of storage that may be feasible economically. Storage of 3 million gallons per square mile would provide an allowable draft rate of 140 mgd with a deficiency at average intervals of ten years, while storage of 30 million gallons per square mile would raise the allowable draft to 250 mgd, which is about half of the mean annual discharge. In addition to the fresh-water resources, saline water from the Delaware River and its tidal estuaries is available in almost unlimited quantity for cooling, fire fighting, some types of washing, and other purposes.