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Site content related to keyword: "Delaware"

RI78 Subsurface Geology of the Area Between Wrangle Hill and Delaware City, Delaware

RI78 Subsurface Geology of the Area Between Wrangle Hill and Delaware City, Delaware

The geology and hydrology of the area between Wrangle Hill and Delaware City, Delaware, have been the focus of numerous studies since the 1950s because of the importance of the local groundwater supply and the potential environmental impact of industrial activity. In this report, 490 boreholes from six decades of drilling provide dense coverage, allowing detailed characterization of the subsurface geologic framework that controls groundwater occurrence and flow.

The region contains a lower section of tabular Cretaceous strata (Potomac, Merchantville, Englishtown, Marshalltown,and Mount Laurel Formations in ascending order) and a more stratigraphically complex upper section of Pleistocene-to-modern units (Columbia, Lynch Heights, and Scotts Corners Formations, latest Pleistocene and Holocene surficial sediments and estuarine deposits). The lowermost Potomac Formation is a mosaic of alluvial facies and includes fluvial channel sands that function as confined aquifer beds; however, the distribution of aquifer-quality sand within the formation is extremely heterogeneous. The Merchantville Formation serves as the most significant confining layer. The Columbia Formation is predominantly sand and functions as an unconfined aquifer over much of the study area.

To delineate the distribution and character of the subsurface formations, densely spaced structural-stratigraphic cross sections were constructed and structural contour maps were created for the top of the Potomac Formation and base of the Columbia Formation. The Cretaceous formations form a series of relatively parallel strata that dip gently (0.4 degrees) to the southeast. These formations are progressively truncated to the north by more flatly dipping Quaternary sediments, except in a narrow north-south oriented belt on the east side of the study area where the deeply incised Reybold paleochannel eroded into the Potomac Formation.

The Reybold paleochannel is one of the most significant geological features in the study area. It is a relatively narrow sandfilled trough defined by deep incision at the base of the Columbia Formation. It reaches depths of more than 110 ft below sea level with a width as narrow as 1,500 ft. It is interpreted to be the result of scour by the sudden release of powerful floodwaters from the north associated with one or more Pleistocene deglaciations. Where the Reybold paleochannel cuts through the Merchantville confining layer, a potential pathway exists for hydrological communication between Columbia and Potomac aquifer sands.

East of the paleochannel, multiple cut-and-fill units within the Pleistocene to Holocene section create a complex geologic framework. The Lynch Heights and Scotts Corners Formations were deposited along the paleo-Delaware River in the late Pleistocene and are commonly eroded into the older Pleistocene Columbia Formation. They are associated with scarps and terraces that represent several generations of sea-level-driven Pleistocene cut-and-fill. They, in turn, have been locally eroded and covered by Holocene marsh and swamp deposits. The Lynch Heights and Scotts Corners Formations include sands that are unconfined aquifers but complicated geometries and short-distance facies changes make their configuration more complex than that of the Columbia Formation.

Delaware Geologic Research Symposium 2013 - Schedule

Delaware Geologic Research Symposium 2013
-Schedule-

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Delaware Geologic Research Symposium - April 16, 2013

Delaware Geologic Research Symposium - April 16, 2013

The Delaware Geological Survey is hosting a research symposium consisting of presentations related to geologic programs and research in Delaware. This meeting is targeting geoscience professionals as well as planners, engineers, and others that use geologic data. Documentation for PG or other applicable continuing education credits will be made available for those attending.

Our symposium will feature talks by the DGS staff on recent and ongoing research. Topics include modeling the impacts of wastewater irrigation on groundwater quality, new techniques for determining submarine discharge of groundwater and sea level issues, stratigraphy of the Potomac Formation, and geologic mapping in Sussex County.

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Presentations at GSA (Geological Society of America) 2012 Annual Meeting

David Wunsch, director of the Delaware Geological Survey and state geologist, and Peter McLaughlin, senior scientist with the Delaware Geological Survey, attended the annual meeting of Geological Society of America in Charlotte, N.C., Nov. 4-7.

Stream and Tide Gage Data for Hurricane Sandy

GOES Satellite Image of Hurricane Sandy (Image provided by NASA)

Hurricane Sandy was a major storm event for the tidal areas of Delaware. As a part of the mission of the Delaware Geological Survey, we have compiled preliminary data related to Delaware tide and stream levels related to the Hurricane Sandy and compared them with previous flooding records.

Celebrating Earth Science - Delaware Geological Survey supplies educational materials to teachers for Earth Science Week

Delaware Geological Survey’s David Wunsch helps prepare for Earth Science Week by distributing educational kits at Coast Day on Oct. 7.

Delaware Geological Survey recently distributed Earth Science Week teacher kits at Coast Day.

United States Geoscience Information Network (USGIN)

United States Geoscience Information Network (USGIN)
Project Contact(s):

The United States Geoscience Information Network (USGIN) initiative is the product of a partnership between the Association of American State Geologists (AASG) and the United States Geological Survey (USGS) created to facilitate discovery of, and access to, geoscience information provided by state and federal geological surveys of the United States. DGS has entered into a partnership with the Arizona Geological Survey (AZGS) to participate in USGIN by establishing a metadata clearinghouse node for Delaware.

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The Earthquake of August 23, 2011

Seismograph recording of the August 23, 2011 earthquake

Delaware and surrounding areas experienced an earthquake event on the afternoon of Tuesday, August 23, 2011. According to the US Geological Survey, a magnitude 5.8 earthquake struck at 1:51 p.m. in central Virginia, in an area referred to as “the Central Virginia Seismic Zone” because of its relatively active earthquake activity for the region. The epicenter was located five miles south-southwest of Mineral, Virginia, with the quake was focused at a depth of 6 km (3.7 miles) below the surface (http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/se082311a.html). The Virginia Geological Survey reports that this is the largest Virginia earthquake known in historic times. A few small aftershocks have occurred in the hours afterward.

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Delaware Groundwater Monitoring Network

The Delaware Geological Survey (DGS) currently monitors groundwater levels in a network of 68 wells in Delaware. Long time-series of water levels in major aquifers serve as critical baseline data for resource management and analyses of aquifer response to pumping, climatic variability, drought hazards, seawater intrusion, and interaction with streams and their ecosystems.

A flood of innovation - UD and the state work together to mitigate coastal flooding in Delaware

Two state agencies, the Delaware Emergency Management Agency (DEMA) and the Delaware Department of Natural Resources and Environmental Control (DNREC), collaborated with the University of Delaware and the Delaware Geological Survey (DGS) and found an answer in the Delaware Environmental Observing System (DEOS). DEOS was created in 2003 as a real-time, regional monitoring system that provides data on weather conditions, water levels, snow depth, and various other environmental factors obtained from automated weather stations in and around the state.

DGS Geologic Map No. 16 (Fairmont Rehoboth Beach Quadrangles) Dataset

DGS Geologic Map No. 16 (Fairmont Rehoboth Beach Quadrangles) Dataset

This vector data set contains the rock unit polygons for the surficial geology in the Delaware Coastal Plain covered by DGS Geologic Map No. 16 (Fairmount and Rehoboth Beach quadrangles). The geologic history of the surficial units of the Fairmount and Rehoboth Beach quadrangles is that of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to sea-level fluctuations during the Pleistocene. The geology reflects this complex history both onshore, in Rehoboth Bay, and offshore. Erosion during the late Pleistocene sea-level low stand and ongoing deposition offshore and in Rehoboth Bay during the Holocene rise in sea level represent the last of several cycles of erosion and deposition.

To facilitate the GIS community of Delaware and to release the geologic map of the Fairmount and Rehoboth Beach quadrangles with all cartographic elements (including geologic symbology, text, etc.) in a form usable in a GIS, we have released this digital coverage of DGS Geological Map 16. The update of earlier work and mapping of new units is important not only to geologists, but also to hydrologists who wish to understand the distribution of water resources, to engineers who need bedrock information during construction of roads and buildings, to government officials and agencies who are planning for residential and commercial growth, and to citizens who are curious about the bedrock under their homes. Formal names are assigned to all rock units according to the guidelines of the 1983 North American Stratigraphic Code (NACSN, 1983).

Delaware Geologic Mapping Program (STATEMAP)

STATEMAP Status Map

The Delaware Geological Survey has a continuing program to map the geology of the entire state at the detailed scale of 1:24,000. The STATEMAP component of the National Cooperative Geologic Mapping Program has contributed significantly to our surficial geologic mapping program. This work has resulted in not only new geologic mapping, but also the digital compilation of previous mapping. Products of this program include file formats that can be downloaded and printed from the web as geologic map products and imported into GIS software as georeferenced layers.

Delaware Geological Survey - US Geological Survey Stream and Tide Gaging Program

The US Geological Survey in cooperation with the Delaware Geological Survey through a State-Federal partnership program operates and maintains stream and tide gages throughout Delaware. The streamgage network is a component of the National Streamflow Information Program (NSIP), a program that provides real-time and long-term current and historical streamflow information that is not only accurate and unbiased, but also meets the needs of many users.

IS7 The Delaware Geological Survey

IS7 The Delaware Geological Survey

IS7 is a foldout brochure that briefly discusses the background and current activities of the DGS. Specifically, the following major programs are listed: Geology, Hydrology, Cartographic Information, Geologic Hazards, Seismograph Network, Outer Continental Shelf, Mineral Resources, Well Records and Sample Library, Publications, and Joint-funded Programs.

IS5 Earthquakes in Delaware

IS5 Earthquakes in Delaware

Delaware is not in a seismically active region but, even here, earthquakes occur because of sudden adjustments in the earth's crust. Even though such movements can be startling they yield important information about the behavior of the earth and the potential for future events. The Delaware Geological Survey continually monitors seismicity in the State because of both the scientific value of the information and to help address the concern of residents and other agencies over possible effects.

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IS1 Delaware Geological Survey Cartographic Information Center

IS1 Delaware Geological Survey Cartographic Information Center

The Delaware Geological Survey Cartographic Information Center has made the DGS a focal point for questions concerning the availability of all types of aerial photography, thematic maps, planimetric maps, topographic maps, historic maps, LANDSAT imagery, space imagery, side looking aerial radar imagery (SLAR), and geodetic control. Sources of maps, charts, aerial photography, boundary mark information, and vertical geodetic control can be obtained for your area of interest within the State through the Center's computer-searchable data bases. In addition, through the Center's affiliation with the U. S. Geological Survey's National Cartographic Information Center (NCIC) in Reston, Virginia, we can locate all cartographic materials covering the United States produced by federal agencies.

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DGS Reinvents Itself on the Web

Screenshot of the new DGS web site
Date: Sep 2010

The Delaware Geological Survey has unveiled a new version of their public web site. Although many of the technologies employed are consistent with modern web standards, giving the user a familiar feel and comfort level, particular attention has been paid to information and the retrieval of it. The site is designed to encourage users to explore content they wouldn't other wise read.

DGS unveils new website

The Delaware Geological Survey has unveiled a new version of their public web site. Although many of the technologies employed are consistent with modern web standards, giving the user a familiar feel and comfort level, particular attention has been paid to information and the retrieval of it.