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Site content related to keyword: "New Castle County"

Columbia Formation

Qcl

Yellowish- to reddish-brown, fine to coarse, feldspathic quartz sand with varying amounts of gravel. Typically cross-bedded with cross-sets ranging from a few inches to over three feet in thickness. Scattered beds of tan to reddish-gray clayey silt are common. In places, the upper 5 to 25 feet consists of grayish- to reddish-brown silt to very fine sand overlying medium to coarse sand. Near the base, clasts of cobble to small boulder size have been found in a gravel bed ranging from a few inches to three feet thick. Gravel fraction primarily quartz with lesser amounts of chert. Clasts of sandstone, siltstone and shale from the Valley and Ridge, and pegmatite, micaceous schist, and amphibolite from the Piedmont are also present. Fills a topographically irregular surface, is less than 50 feet thick, and is interpreted to be primarily a body of fluvial glacial outwash sediment (Jordan, 1964; Ramsey, 1997). Pollen indicate deposition in a cold climate during the middle Pleistocene (Groot and Jordan, 1999).

Lynch Heights Formation

Qlh

Heterogeneous unit of light-gray to brown to light-yellowish brown, medium to fine sand with discontinuous beds of coarse sand, gravel, silt, fine to very fine sand, and organic-rich clayey silt to silty sand. Upper part of the unit commonly consists of fine, well-sorted sand. Small-scale cross-bedding within the sands is common. Some of the interbedded clayey silts and silty sands are burrowed. Beds of shell are rarely encountered. Sands are quartzose and slightly feldspathic, and typically micaceous where very fine to fine grained. Unit underlies a terrace parallel to the present Delaware Bay that has elevations between 50 and 30 feet. Interpreted to be a fluvial to estuarine unit of fluvial channel, tidal flat, tidal channel, beach, and bay deposits (Ramsey, 1997). Overall thickness ranges up to 50 feet.

RI46 Shallow Subsurface Temperatures at Selected Locations in Delaware

RI46 Shallow Subsurface Temperatures at Selected Locations in Delaware

Subsurface temperatures were measured in instrumented boreholes for about one and one-half years at depths down to 10 feet below land surface at four locations in the State. In New Castle County, temperatures were measured periodically in the field about twice a month at three sites, and, in Sussex County, they were automatically recorded every 15 minutes at one site. The depths of interest are generally in the unsaturated zone and are subject to both daily temperature fluctuations and longer seasonal changes.

Scotts Corners Formation

Qsc

Heterogeneous unit of light-gray to brown to light-yellowish-brown, coarse to fine sand, gravelly sand and pebble gravel with rare discontinuous beds of organic-rich clayey silt, clayey silt, and pebble gravel. Sands are quartzose with some feldspar and muscovite. Commonly capped by one to two feet of silt to fine sandy silt. Laminae of opaque heavy minerals are common. Unit underlies a terrace parallel to the present Delaware River that has elevations less than 25 feet. Interpreted to be a transgressive unit consisting of swamp, marsh, estuarine channel, beach, and bay deposits. Climate during the time of deposition was temperate to warm temperate as interpreted from fossil pollen assemblages (Ramsey, 1997). Overall thickness of the unit rarely exceeds 20 feet.

Lamp Shells: Phylum Brachiopoda

Brachiopods are shelled invertebrate that look somewhat like bivalved molluscs. However, the animal living in the shell is a filter feeder that collects food with a special organ called a lophopore (bryzozoa also have lophophores).

Moss Animals: Phylum Bryozoa

Bryozoans, sometimes referred to as "moss animals," are a type of simple colonial animal that mostly lives in marine environments (a few inhabit freshwater). Bryozoans feed by means of a lophophore, a small ring of tentacles covered with tiny cilia that are used to filter food from the water. Bryozoan colonies are protected with a covering of organic materials or calcium carbonate. Some calcium carbonate forms may be found as fossils in the Cretaceous strata near the C & D Canal.

Corals and Jellyfish: Phylum Cnidaria

Cnidarians are soft-bodied animals that include corals, jellyfish, and sea anemones. These soft-bodied animals have saclike digestive cavities and tentacles containing rows or stinging cells used for defense and capture of food. Many secrete calcium carbonate to support and partly enclose the soft parts; the most familiar of these are corals. The only members of the phylum found at the Canal are solitary corals. One of these corals, Micrabacia, may be the most common fossil found. Another common fossil found there, a solitary horn-shaped coral, has been given different names by different authors.

Sponges: Phylum Porifera

Phylum Porifera is a group of simple animals that includes the sponges. Porifera have no internal organs, nervous tissue, circulatory system, or digestive systems, making them the most primitive of the multi-cellular animals. To support and protect their soft bodies, sponges produce skeletons of calcium carbonate, silica, or a soft organic material called spongin. The most common fossil sponge in the Cretaceous sediments of Delaware is the genus Cliona. Cliona sponges lived on rocks and shells of the seafloor and commonly bored holes in these objects, in which it lived. To obtain food, the sponges filtered the water around them as it passed through tiny pores located on their outer walls. The sponge is common in the Mount Laurel Formation along the Canal.

One-celled Organisms: Phylum Protozoa

Protozoans are one-celled organisms that include the amoeba. One group of protozoans, the Foraminifera ("forams"), are among the most common fossils found in the Cretaceous of Delaware -- but are hard to study without a microscope. Forams build a hard outer covering -- some by secreting calcium carbonate or opaline silica, some by cementing sand grains -- in order to provide support and protection. The resulting many-chambered shells, which are commonly called "tests," are the parts preserved as fossils. Some are very simple, and others are very ornate.

Cretaceous Fossils Overview

Eastern Entrance of C&D Canal (Source: U.S. Army Corps of Engineers Digital Visual Library)

These pages describes many of the types of fossils that are known from the Cretaceous deposits of Delaware. It includes pictures and drawings of many of the fossils. It also provides a checklist of Delaware's Cretaceous as well as some maps that show collecting sites and the geology of the area.

OFR24 Saturated Thickness of the Water-Table Aquifer in Southern New Castle County, Delaware

OFR24 Saturated Thickness of the Water-Table Aquifer in Southern New Castle County, Delaware

This map shows the saturated thickness of the water-table aquifer. This aquifer consists of the deposits of the Columbia Formation and those portions of the Magothy and Englishtown-Mt. Laurel formations, and Rancocas Group that are hydraulically connected with the Columbia deposits (see Groot, Demicco, and Cherry, 1983). For example, large, saturated thicknesses in the zone trending northeast-southwest near Townsend reflect the addition of the sands of the Rancocas Group to the total thickness of the sands of the overlying Columbia Formation.

OFR23 Ground-Water Availability in Southern New Castle County, Delaware

OFR23 Ground-Water Availability in Southern New Castle County, Delaware

The purposes of the study described in this report are (1) to determine the total amount of fresh ground water (chloride content less than 150 milligrams/liter) available in New Castle County south of the Chesapeake and Delaware Canal, and (2) to map the geographic distribution of available fresh ground water on the basis of areas delineated by one minute of latitude and one minute of longitude (such areas measure essentially one square mile). The investigation has been based solely on data available in various publications and in the files of the Delaware and United States Geological Surveys.

OFR18 A Numerical Indicator of Water Conditions for Northern Delaware

OFR18 A Numerical Indicator of Water Conditions for Northern Delaware

Numerical indicators, or indices, are widely used to measure the status of complex relationships. As such, indices have become accepted by researchers and the public in such disparate fields as economics, air quality, and weather. In this paper we explore the formulation of an indicator of water conditions in northern Delaware, propose formulas that may be applicable, and test those proposals against long-term records of basic data. The need for a simple indicator of water supply conditions in Delaware, and especially in New Castle County, has become increasingly apparent. The Delaware River Basin Commission (DRBC) has applied an index to the Delaware River Basin, which includes a portion of Delaware. The Governor's Drought Advisory Committee has sought an objective means of determining when water supply conditions might warrant conservation measures. Discussions of the subject have also been held within the State Comprehensive Water Management Committee. We are pleased to acknowledge the constructive comments of these groups and of other colleagues with whom we have discussed this work. George R. Phillips of the Delaware Department of Natural Resources and Environmental Control (DNREC) was especially helpful in analyzing the practical implications of using the index presented in this paper. John R. Mather, Delaware State Climatologist, provided Palmer Drought Severity Index values with the cooperation of the National Weather Service. This report was reviewed by Richard N. Benson and John H. Talley of the Delaware Geological Survey (DGS).

OFR11 Effects of Earthquakes and Earth Tides on Water Levels in Selected Wells in the Piedmont of Delaware

OFR11 Effects of Earthquakes and Earth Tides on Water Levels in Selected Wells in the Piedmont of Delaware

Examination of continuous water-level hydrographs from two artesian observation wells in the Piedmont near Newark, Delaware reveals water-level fluctuations caused by earthquakes and by earth tides. The effects of 14 distant earthquakes with MS (surface wave) magnitudes between 6.7 and 8.0 and MB (body wave) magnitudes between 5.9 and 7.0 (National Earthquake Information Service, 1975-1977) have been recorded over a two-year and ten-month period.

OFR49 Hydrologeologic Framework of Southern New Castle County

OFR49 Hydrologeologic Framework of Southern New Castle County

Southern New Castle County is dependent on ground water for nearly all of its water supply. The area has been undergoing development from predominately agricultural land use to urban/suburban land use (Delaware Water Supply Coordinating Council [WSCC], 2006). With this development comes a need to more accurately predict the availability of ground water to reduce the potential of overusing the resource. This report has 3 plates listed as separate files.

Number of Pages: 
27

OFR48 Results of the Domestic Well Water-Quality Study

OFR48 Results of the Domestic Well Water-Quality Study

The Delaware Geological Survey conducted a review of existing ground-water quality data collected from shallow (less than 100 feet deep) domestic water-supply wells and small public water-supply wells (serving fewer than 100 residents) to determine the extent to which toxic and carcinogenic compounds are present in the shallow ground water serving domestic water supply wells. These data were generated by several agencies including the Delaware Geological Survey, U.S. Geological Survey, Delaware Department of Natural Resources and Environmental Control, Delaware Division of Public Health Office of Drinking Water, and the Delaware Department of Agriculture Pesticide Management Program.

Number of Pages: 
55

OFR43 Results of Trenching Investigations Along the New Castle Railroad Survey-1 Seismic Line, New Castle, Delaware

OFR43 Results of Trenching Investigations Along the New Castle Railroad Survey-1 Seismic Line, New Castle, Delaware

Five trenches were excavated to a depth of 5 to 8 ft along the path of an abandoned railroad grade near the city of New Castle to investigate potential near-surface faults that may be related to earthquake activity in northern Delaware. Seismic reflection profiles along this line suggested the existence of significant faulting in the area, which lies along a postulated fault trend in eastern New Castle County. Subsequent drilling, however, failed to substantiate displacement interpreted for faults in the sedimentary section. Detailed examination of exposures in the trenches also failed to reveal the existence of near surface faults. Together these findings suggest that there has been minimal or no modern near-surface fault activity in this area of New Castle County.

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OFR4 Papers Presented by Staff Members of the Delaware Geological Survey at the Baltimore Meeting of the Northeastern Section of the Geological Society of America, March, 1974

OFR4 Papers Presented by Staff Members of the Delaware Geological Survey at the Baltimore Meeting of the Northeastern Section of the Geological Society of America, March, 1974

This report is a compilation of four papers presented by DGS staff members at the Baltimore Meeting of the Northeastern Section of the Geological Society of America, March, 1974.

OFR3 Preliminary Report on the Earthquake of February 28, 1973

OFR3 Preliminary Report on the Earthquake of February 28, 1973

This report has been prepared to fill an immediate need for information on the earthquake that affected northern Delaware on February 28, 1973. Public interest in seismic events has grown in the past two years because of a series of small, local events (Jordan et al., 1972) and has been heightened considerably by the event described in this report. Various stresses on and within the earth lead to periodic adjustments or changes by the rocks making up the earth's crust. Many changes are too slow or small to be measured within a human lifetime, but earthquakes can be a very perceptible phenomenon, expressing more rapid adjustment. Indeed, earthquakes in many areas of the world are a serious geologic hazard and a threat to life and property. Thus, it must be recognized that the earth is a dynamic body and its processes are not bound to the convenience of man.

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OFR2 Preliminary Report on Seismic Events in Northern Delaware

OFR2 Preliminary Report on Seismic Events in Northern Delaware

Earthquakes are an unfamiliar phenomenon in Delaware. Because of the great public and scientific interest in the seismic events that have recently affected northern Delaware, this Open File Report has been prepared to present currently available information concerning the earthquakes and the investigation pursued by the Delaware Geological Survey. This is not a final scientific explanation of the events. To many persons it is shocking to realize that the earth that they regard as stable is, in fact, an active body. The present earth is a product of 4.5 billion years of history, during which time most geologic forces have acted so slowly as to be almost imperceptible. Therefore, sudden movements are disturbing. Earthquakes are the vibrations caused by relatively sudden slippage of deeply buried rocks. Earthquakes occur in a vast range of sizes; many are too small to be felt and others cause great damage. The events in Delaware that are described on these pages were relatively small and, although they warrant further study, which may lead to some precautionary measures, they do not represent cause for alarm.