geophysical

OFR53 Kent County Groundwater Monitoring Project: Results of Subsurface Exploration

This report documents the methods and results derived from subsurface exploration, monitoring well installation, and hydraulic testing conducted during the project "Groundwater and Saline Water Intrusion Monitoring Network Infrastructure Improvements: Kent County, Delaware". This project was focused on the aquifers in Kent County that supply water to wells for domestic, public, irrigation, and commercial uses as well as provide base flow to local streams. From shallowest to deepest, they are the Columbia, Milford, Frederica, Federalsburg, Cheswold, Piney Point, Rancocas, and Mt.

Seismic Network Map

The DGS maintains its own network of seismometers to detect local earthquake activity. Following an earthquake swarm in 1972, the DGS established its first seismometer station in Newark. The network now consists of five seismic stations spread across the state: three stations in the Newark-Wilmington area, one at the DEMA office in southern New Castle County, and one at the Sussex County Emergency Operations Center.

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.

RI42 Stratigraphy and Depositional History of the Post-Choptank Chesapeake Group

Onshore and offshore geological and geophysical data were used to investigate the lithostratigraphy, seismic stratigraphy, and depositional history of the late Tertiary age post-Choptank Chesapeake Group rocks in Sussex County, Delaware and adjacent counties in Maryland. The results of this investigation suggest that the St. Marys (?) Formation and the sandy interval of which the Manokin aquifer is a part, are distinct lithostratigraphic units. The Manokin formation is proposed as an informal lithostratigraphic unit that refers to the sandy interval of which the Manokin aquifer is a part.

OFR10 Preliminary Results of Seismic and Magnetic Surveys off Delaware's Coast

The nature and occurrence of subsurface resources, whether ground water, minerals, or petroleum, are controlled by the geologic history and framework of any particular area. Several years ago the staff of the Delaware Geological Survey began an informal assessment of the potential resources of southern Delaware and demonstrated the lack of basic data on the deep subsurface in this area. This assessment was later summarized by Benson (1976) with particular emphasis on the possibilities for petroleum occurrence.