DGS Reports of Investigations
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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 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 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 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.Item Evaluation Of The Water Resources Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1966-03) Baker, W.W.; Varrin, R.D.; Groot, J.J.; Jordan, R.R.At present, Delaware has an abundance of water for the foreseeable future, but is already faced with water problems in some municipalities. These can only be resolved satisfactorily through complete evaluation of the State's water resources and the establishment of a coordinated program of water management.Item Ground-Water Levels In Delaware January, 1962 - June, 1966(Newark, DE: Delaware Geological Survey, University of Delaware, 1967-04) Woodruff, K.D.This report deals with fluctuations in nine observation wells during the period 1960 - 1966. These wells are part of a state-wide ground-water monitoring network and are located in areas of little or no pumping. Eight of the wells respond to water-table conditions; the ninth well appears to reflect artesian conditions. Although precipitation throughout Delaware was generally below average during the period covered by this report, annual average water levels declined very little in the wells reported on here. There is some evidence, however, for a lowering of water-table levels by three to four feet during the period 1960 - 1962.Item Pleistocene Channels Of New Castle County, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1967-05) Spoljaric, N.Two Pleistocene channel-systems are recognized in New Castle County, (1) a system of straight channels located in the area north of the Chesapeake and Delaware Canal and (2) a braided system occupying the area south of the Canal. Fluctuations of the flow regime of Pleistocene streams were frequent as evidenced by sedimentary structures and widespread distribution of gravels in the channel deposits. During high stream flows most of the study area was submerged, while during low flows large interstream areas and islands emerged. The transporting agents of the Pleistocene sediments were primarily melt-water streams originating below glaciers which at times advanced to within 100 miles north of New Castle County. Thus, the age of the deposits is thought to be glacial, but there is no indication as to which glacial stage they belong. However, the channels appear to have been formed contemporaneously by a major distributary system.Item An Evaluation Of The Resistivity And Seismic Refraction Techniques In The Search For Pleistocene Channels In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1967-06) Bonini, W.E.Pleistocene channels along the margins of the Atlantic Coastal Plain are developed in crystalline and Triassic sediments (Bonini and Hickok, 1958), or into the Cretaceous and Tertiary coastal plain sediments (Widmer, 1965). Deposits in these channels consist of sand and gravel with amounts of silt and clay. For example, the Bear area channel is 50 to 70 feet deep and contains up to 30 feet of sand and gravel overlain by sandy clay. Because they are usually more permeable than the older deposits into which the channels are developed, Pleistocene deposits are important in ground water studies for several reasons: (1) where they are thick enough they may be used as aquifers, as in the case of the Bear channel, and (2) these beds can effectively increase the recharge into the underlying aquifers by absorbing precipitation and transmitting the water to them.Item Quantitative Lithofacies Analysis Of Potomac Formation, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1967-10) Spoljaric, N.The quantitative lithofacies analysis of the Potomac Formation in a small area west of Delaware City revealed that the deposition of these sediments was continuous throughout the time of their formation. The uppermost part of the Potomac sequence appears to have been removed, probably by erosion, prior to the deposition of the younger Upper Cretaceous marine sediments. The sand bodies contained in Potomac deposits have a shoestring channel form and were most probably deposited by unidirectional currents. The direction of the flows, however, cannot be determined on the basis of the available subsurface data.Item The Occurrence Of Saline Ground Water In Delaware Aquifers(Newark, DE: Delaware Geological Survey, University of Delaware, 1969-08) Woodruff, K.D.The location of the fresh-salt-water-boundary in the deeper aquifers of Delaware is related mainly to head values. Near coastal areas, dynamic conditions may prevail that affect the interface position within shallow aquifers open to the sea. Holocene and Columbia sands which form Delaware's shallow water-table aquifers contain brackish water in scattered coastal areas while brackish water in the artesian aquifers is found at various depths. Water from Chesapeake Group sediments (Miocene) is fresh in Kent County but is salty in poorly defined areas of Sussex County. The interface in the Piney Point Formation (Eocene) lies just north of Milford and extends in a northeast-southwesterly direction across the State. Brackish water exists in the Magothy and Potomac formations of Cretaceous age a few miles south of Middletown. Heavy pumping near sources of brackish water should be avoided for the present. Proper location of monitoring wells is necessary for detection of future chloride movement.Item Delaware Clay Resources(Newark, DE: Delaware Geological Survey, University of Delaware, 1970-06) Pickett, T.E.Forty-eight samples of Delaware clays were collected and tested jointly by the Delaware Geological Survey and the U. S. Bureau of Mines. Clays potentially useful for face brick are common. The nonmarine Cretaceous Potomac Formation is a potential economic clay at virtually all locations sampled. Some Miocene and Pleistocene clays are also possibilities for brick clays. Other Potomac clays are potential sources for glazed tile, sewer pipe, refractory brick, and stoneware. Coastal marsh clays, frequently containing much organic debris, are potential source material for lightweight aggregate used in lightweight, strong concrete products. Lightweight aggregate has the potential for augmenting dwindling reserves of crushed stone and gravel aggregate.Item General Ground-Water Quality In Fresh-Water Aquifers Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1970-07) Woodruff, K.D.Information on ground-water quality in Delaware has become critical for three reasons: (1) increased water demand, (2) need for a better understanding of ground-water flow patterns, (3) need for a "base" against which future quality changes can be measured. Analyses of about 150 water quality samples from wells show that Delaware's fresh ground waters are suitable for most purposes. High iron content may occur, however, in wells tapping the Columbia and the Potomac formations. Overall, total dissolved solids in Delaware aquifers are relatively low except in the Cheswold and Frederica aquifers (Miocene), and possibly parts of the Piney Point Formation (Eocene).Item Application Of Geophysics To Highway Design In The Piedmont Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1971-06) Woodruff, K.D.The feasibility of using geophysical techniques in determining the amount of overburden and the nature of the subsurface along a proposed highway was tested in the Piedmont area of Delaware. The area is underlain by crystalline rocks capped by varying amounts of unconsolidated material or regolith. Seismic refraction and surface resistivity methods were used at selected stations and the interpretations were later compared to results from test holes and to the material exposed in road cuts. In general, interpretation of the seismic refraction results compared quite well with test borings and with field observations made after construction was started. Resistivity data were inconclusive in themselves but provided some additional control points when correlated with seismic refraction data. With proper control, it is concluded that such techniques could be useful in the Piedmont of Delaware for highway planning.Item Ground-Water Geology Of The Delaware Atlantic Seashore(Newark, DE: Delaware Geological Survey, University of Delaware, 1971-08) Miller, J.C.The need for locating additional sources of ground water for the Delaware Atlantic seashore, a predominantly recreation-oriented area, is indicated by an expanding population in the belt between Philadelphia, Pennsylvania and Washington, D.C., combined with increasing leisure time. Present water use in the shore area is approximately 4 million gallons per day and will reach 9.3 million gallons per day by the year 2000. A new geologic interpretation of the occurrence of deep aquifers in the Delaware Atlantic seashore area is presented. Recent data from deep wells has enabled the construction of a more accurate geologic framework upon which the hydrologic data are superimposed. Correlation of Miocene sands concludes that the Manokin aquifer lies at greater depths in southeastern Delaware than previously thought.Item Geology Of The Fall Zone In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1972-03) Spoljaric, N.The complex geologic framework of the Fall Zone in Delaware is primarily caused by diverse structural features present in the crystalline basement rocks that have exerted a considerable influence on the distribution of the overlying sediments of the Coastal Plain.Item Guide To Common Cretaceous Fossils Of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1972-05) Pickett, T.E.This guide contains illustrations of fossils from Delaware Geological Survey Bulletin No. 3 ("Marine Upper Cretaceous Formations of the Chesapeake and Delaware Canal") and Report of Investigations No. 7 ("An Invertebrate Fauna from the Upper Cretaceous of Delaware"). The identifications have been revised to be as accurate as possible so that this guide will be useful to those fossil collectors interested in classifying their "finds."Item Geology And Ground Water, University Of Delaware, Newark, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1972-05) Woodruff, K.D.; Miller, J.C.; Jordan, R.R.; Spoljaric, N.; Pickett, T.E.The results of an intensive ground-water study on University of Delaware lands in the Newark area revealed additional sources of available ground water. Geophysical techniques, air-photo interpretation, studies of existing data, field mapping, test drilling, and pump tests were used as the bases for guiding additional well development. The study, conducted by the Delaware Geological Survey, was a cooperative effort between the University of Delaware and the City of Newark in response to mutual water supply problems. A potential ground-water yield of about 500 gpm was discovered on the University Laird Tract in the Piedmont Province. Ground water available from other locations in the Coastal Plain portion of the study area may total about 175 gpm. However, careful well development and proper well spacing will be necessary to obtain optimum yields.