Petrography is a branch of geoscience focused on the description and classification of rocks, primarily by microscopic study of optical properties of minerals. A thin sliver of rock is cut from a sample, mounted on a glass slide, ground to approximately 30 microns (0.03mm), and viewed under a microscope that uses polarized light. By observing the colors produced as plain polarized light and crossed (90 degrees) polarized light shines through the minerals, petrologists can determine the minerals that comprise the sampled rock.
The geological history of the surficial units of the Clayton, Smyrna, and the Delaware portion of the Millington Quadrangles are the result of deposition of the Beaverdam Formation and its modification by erosion and deposition of the Columbia Formation during the early Pleistocene. These units were then modified by the Lynch Heights and Scotts Corners Formations as a result of sea-level fluctuations during the middle to late Pleistocene. The geology is further complicated by periglacial activity that produced Carolina Bay deposits in the map area, which modified the land surface.
Geologic maps at the DGS are created as primary deliverables of a project and as derivatives of other projects. Primary deliverables are mainly those that are the result of outside funding sources such as the AASG-USGS cooperative StateMap. Derivative maps are those that have primary data collected for reasons other than geologic mapping can be used to create geologic maps or that geologic maps are derivative products of a project rather than the primary goal of a project.
The geological history of the surficial units of the Seaford East Quadrangle and the Delaware portion of the Seaford West Quadrangle was the result 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 by the cut and fill geometry of the middle and late Pleistocene deposits incised into the Beaverdam Formation.
-Public, private and academic partners came together on Tuesday, April 14, in the Rodney Room of the University of Delaware’s Perkins Student Center for the second biennial Delaware Geologic Research Symposium, hosted by the Delaware Geological Survey and the College of Earth, Ocean, and Environment.
Over 100 geological researchers, state representatives, industrial partners and University students and faculty shared and observed presentations on the latest geological research initiatives in Delaware, and what they mean for the state, its environment and its citizens.
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.