Delaware Geological Survey
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The Delaware Geological Survey (DGS) was first established by the General Assembly in 1837. It was reestablished by that body in 1951 and is a senior natural resources unit in Delaware. The Delaware Geological Survey's mission is, by statute, geologic and hydrologic research and exploration, and dissemination of information through publication and public service.
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Item Memoir of the Geological Survey of the State of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1841) Booth, J.C.The following report of the geological survey of the state of Delaware, conducted in the years 1837 and 1838, embraces all the observations and examinations which were made during the continuance of the survey, including those contained in the first and second annual reports, already laid before the legislature.Item Ground-Water Problems In Highway Construction And Maintenance(Newark, DE: Delaware Geological Survey, University of Delaware, 1953) Rasmussen, W.C.; Haigler, E.B.This report discusses the occurrence of ground water in relation to certain problems in highway construction and maintenance. These problems are: the subdrainage of roads; quicksand; the arrest of soil creep in road cuts; the construction of lower and larger culverts necessitated by the farm-drainage program; the prevention of failure of bridge abutments and retaining walls; and the watercement ratio of sub-water-table concrete. Although the highway problems and suggested solutions are of general interest, they are considered with special reference to the State of Delaware, in relation to the geology of that State. The new technique of soil stabilization by electroosmosis is reviewed in the hope that it might find application here in road work and pile setting. Field application by the Germans and Russians is reviewed.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 Preliminary Report On The Geology And Ground-Water Resources Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1955-05) Marine, I.W.; Rasmussen, W.C.Delaware has an abundant supply of ground water of a quality suitable for most purposes. About 30 million gallons of water a day was pumped from the ground in 1954. It is estimated that this is roughly 1/16 of the optimum yield. This water is derived from nine groups or series of water-bearing units and is obtained from wells which yield as much as 1,100 gallons per minute. Thousands of wells serve agriculture, industry, municipalities, and domestic users. Geographically, Delaware is situated along the Atlantic coast of the United States in two physiographic provinces: the Piedmont and the Coastal Plain. The Piedmont is a belt of rolling foothills of the Appalachian Mountains. It is separated from the Coastal Plain by the Fall Line, a narrow zone of rapids or falls along which rivers and creek descend rapidly from the mature valleys of the Piedmont to the sluggish tidal estuaries of the coastal area. The Coastal Plain is a flat or gently undulating plain of relatively low altitude, which borders the Atlantic Ocean and its estuarine embayments.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 Story of Your State Geological Survey's Search for Water(Newark, DE: Delaware Geological Survey, University of Delaware, 1956) DGS StaffThis is a brief story about water and the ways in which the Delaware Geological Survey helps insure that you will always have a plentiful supply of this precious natural resource.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.Item Salinity of the Delaware Estuary(Newark, DE: Delaware Geological Survey, University of Delaware, 1957-07) Cohen, B.The purpose of this investigation was to obtain data on and study the factors affecting the salinity of the Delaware River from Philadelphia, Pennsylvania to Reedy Island, Delaware. The techniques of analyses of data and results of the analyses are presented.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 High-Capacity Test Well Developed At The Air Force Base, Dover, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1958-06) Rasmussen, W.C.; Groot, J.J.; Depman, A.J.A thick aquifer of Eocene age underlies the Dover area, Delaware at depths ranging from 250 to 400 feet below the land surface. The aquifer is about 250 feet thick beneath the Dover Air Force Base and is composed of fairly uniform medium to fine glauconitic quartz sand. The static water level in a test well at the base was 18 feet below the land surface, or 5.7 feet above sea level, on April 17, 1957. The yield of the test well was about 300 gpm (gallons per minute), and the specific capacity at the end of a 12-hour pumping period was 8.3 gpm per foot of drawdown.Item Wells For The Observation Of Chloride And Water Levels In Aquifers That Cross The Chesapeake And Delaware Canal(Newark, DE: Delaware Geological Survey, University of Delaware, 1958-08) Rasmussen, W.C.; Groot, J.J.; Beamer, N.H.Three test wells were drilled near the banks of the Chesapeake and Delaware Canal, in aquifers formed by sand beds in two geologic units, the nonmarine Cretaceous sediments and the Magothy formation, which crop out along the sides and across the bottom of the canal. The canal carries tidal flow from the Delaware River to and from Chesapeake Bay. The purpose of the wells was to determine whether salt water from the canal has entered the water-bearing beds of these formations, and to determine the head of water in them. It was found that the sands contain fresh water, uncontaminated, and that apparently there was discharge of fresh water from the aquifers to the canal under low head, at least from the winter of late 1955 through early autumn 1957.Item Water Resources Of Sussex County, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1960-12) Rasmussen, W.C.; Wilkens, R.A.; Beall, R.M.; OthersSussex County is in the Atlantic Coastal Plain. Its relatively flat, featureless topography is characterized by two terrace-like surfaces; the lower one rises from sea level to about 40 feet above sea level, and the higher one rises inland from 40 to about 60 feet above sea level. Peculiar landforms of low relief, broad ovals, similar to the "Carolina bays,” and to the “New Jersey basins" are common on the sandy flat divides in Sussex County. Hydrologically, they are sites of much ground-water discharge, by evapotranspiration, from meadow and marsh of lush vegetation.Item Long-Range Plan For Water Resources Investigations In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1961-02) DGS StaffIn order to obtain sufficient data which will enable the State to develop its water resources to the fullest extent of which they are capable, a series of systematic investigations is necessary. A long-range plan describing these studies is the subject of this report. A brief discussion of water in Delaware is presented first to provide a proper background for the long-range plan. The plan itself merely outlines the overall objectives and types of investigational work that must be pursued if the State is to develop its water resources wisely.Item Possibilities For The Storage Of Natural Gas In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1961-05) Adams, J.K.; Jordan, R.R.Item Planktonic Foraminifera And The Cretaceous-Tertiary Boundary In Central Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1962-02) Jordan, R.R.The uppermost Cretaceous and lowermost Tertiary planktonic Foraminifera obtained from cores taken in a deep well near Dover, Delaware are studied. The Cretaceous foraminifers are of the Heterohelix-Globotruncana assemblage and are probably of late Maescrichtian age. The Danian Globorotalia compressa - Globigerinoides daubjergensis zone lies immediately above. The Cretaceous-Tertiary boundary is at a depth of approximately 980 feet and lies within a gray, glauconitic silt.Item Some Observations On The Sediments Of The Delaware River South Of Wilmington(Newark, DE: Delaware Geological Survey, University of Delaware, 1962-02) Jordan, R.R.; Groot, J.J.A series of cores was obtained from a boring in the sediments of the Delaware River near the Delaware Memorial Bridge. The mineralogy, texture and palynology of these samples have been studied. The sedimentary and palynological records suggest that the Delaware River, while swollen with Wisconsin meltwaters, deepened its channel and that subsequent flooding of the mouth of the stream by rising sea waters initiated the deposition of estuarine silts in post-Wisconsin time.Item Stratigraphy Of The Sedimentary Rocks Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1962-11) Jordan, R.R.The stratigraphy of the Coastal Plain of Delaware is discussed with emphasis placed upon an appraisal of the stratigraphic nomenclature. A revised stratigraphic column for Delaware is proposed. Rock stratigraphic units, based mainly on data from certain key wells, are described and the published names which have been or which might conceivably be applied to those units are reviewed. In each case a name is chosen and the reasons for the choice are stated. The relationships between the column established for Delaware and the recognized columns for adjacent states are considered. The rock units of the Coastal Plain of New Jersey, Delaware, and Maryland form an interrelated mass. However, profound facies changes do occur, particularly in the dip direction, but also along the strike. Thus, attempts to extend units established in the outcrop belt almost indefinitely into the subsurface have been unsatisfactory.Item Salinity Of The Delaware Estuary(Newark, DE: Delaware Geological Survey, University of Delaware, 1963-02) Cohen, B.; McCarthy, L.T. Jr.The purpose of this investigation was to obtain data on and study the factors affecting the salinity of the Delaware River from Philadelphia, Pa., to the Appoquinimink River, Del. The general chemical quality of water in the estuary is described, including changes in salinity in the river cross section and profile, diurnal and seasonal changes, and the effects of rainfall, sea level, and winds on salinity. Relationships are established of the concentrations of chloride and dissolved solids to specific conductance. In addition to chloride profiles and isochlor plots, time series are plotted for salinity or some quantity representing salinity, fresh-water discharge, mean river level, and mean sea level. The two major variables which appear to have the greatest effect on the salinity of the estuary are the fresh-water flow of the river and sea level. The most favorable combination of these variables for salt-water encroachment occurs from August to early October and the least favorable combination occurs between December and May.Item An Invertebrate Macrofauna From The Upper Cretaceous Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1963-07) Richards, H.G.; Shapiro, E.Recent erosion along the Chesapeake and Delaware Canal has exposed an unusually rich Upper Cretaceous fossiliferous outcrop at the Biggs Farm, near the eastern end of the Canal. Some III species of mollusks representing 72 genera have been identified. Coelenterata, Porifera, Annelida, Brachiopoda, Crustacea, and a few fragmentary vertebrate remains have also been found. Five species are being described as new, and there are 54 new records for the Cretaceous of Delaware. The preservation of the material suggests that the animals lived on a sandy bottom in water between 50 and 100 feet in depth, possibly near the mouth of a bay. Inasmuch as there is a mixing of some species characteristic of the Matawan Group and other species characteristic of the Monmouth Group, it is believed that the fauna at this locality lies near the Matawan-Monmouth boundary, perhaps in the lower part of the Monmouth Group.