The Delaware Geological Survey (DGS) has published a report that details new findings on the subsurface geology of the Delaware City area.

Titled Subsurface Geology of the area between Wrangle Hill and Delaware City, Delaware, Report of Investigations Number 78 presents the results of cooperative research between geological consultant John W. Jengo of the firm MWH Americas and DGS researchers Peter P. McLaughlin Jr. and Kelvin W. Ramsey.

The geology and hydrology of the area between Wrangle Hill and Delaware City have been examined in many site-specific studies since the 1950s because of the need to understand possible implications of industrial activity for groundwater protection. This study integrates data from nearly 500 boreholes drilled over the last six decades and establishes, for the first time, a comprehensive view of the subsurface geology that helps better characterize the hydrogeology of the area.

The report includes two subsurface geological maps and one surficial geologic map of the study area as well as 10 stratigraphic cross sections that show the vertical and horizontal relationships of the subsurface geologic units.

The findings from this study reveal that older, generally parallel-layered geologic units that underlie the site have, along a well-defined narrow channel axis, been deeply eroded and filled by younger sand deposits. Where this feature cuts through underlying hydrologic confining layers, a potential pathway exists for hydrological communication between the surficial aquifer and deeper confined aquifers.

DGS Report of Investigations No. 78 is part of the Delaware Geological Survey’s ongoing mission to understand geologic and hydrologic systems and to advise, inform, and educate Delawareans about the results of such investigations for use in issues regarding surface and groundwater resources, agriculture, economic development, land-use planning, environmental protection, resource evaluation, engineering applications, hazard identification and mitigation, and recreation. It is available in PDF format from the DGS website.