Wilmington

RI34 Long-Term Chemical-Quality Changes in Selected Delaware Streams

Data from three streamflow water-quality stations were statistically analyzed to determine the relationships of the major inorganic chemical constituents to specific conductance and to stream discharge. The results show that ion concentrations varied directly with the flow and with specific conductance. A set of regression equations defining these relationships were derived for each of the three stations: Brandywine Creek at Wilmington, St. Jones River at Dover, and Nanticoke River near Bridgeville.

Earthquake rattles New Jersey and Delaware

Date

A minor earthquake occurred near Pennsville, N.J., at 9:44 a.m., Wednesday, July 1, according to the Delaware Geological Survey (DGS) at the University of Delaware. The earthquake, which had a magnitude of 2.8, was recorded at the three northern stations of the DGS seismic network.

RI19 Geology of the Fall Zone in Delaware

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.

RI16 Application of Geophysics to Highway Design in the Piedmont of Delaware

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.

GM13 Geologic Map of New Castle County, Delaware

This map shows the surficial geology of New Castle County, Delaware at a scale of 1:100,000. Maps at this scale are useful for viewing the general geologic framework on a county-wide basis, determining the geology of watersheds, and recognizing the relationship of geology to regional or county-wide environmental or land-use issues. This map, when combined with the subsurface geologic information, provides a basis for locating water supplies, mapping ground-water recharge areas, and protecting ground and surface water.

RI6 Some Observations on the Sediments of the Delaware River South of Wilmington

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.