Browsing by Author "Wang, L.T."
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Item Delaware Geological Survey Petrographic Data Viewer(Newark, DE: Delaware Geological Survey, University of Delaware, 2021-05) Schenck, W.S.; Wang, L.T.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 data and photomicrographs of thin sections within the Delaware Geological Survey (DGS) Petrographic Data Viewer represent the total collection of the Delaware Geological Survey for the Delaware Piedmont and surrounding areas. The data viewer includes slides from DGS research, slides donated by researchers, and slides culled from class reports, master's theses, and Ph.D. dissertations. Within the application, the “Slide Made For” field identifies the original owner of the thin section. The researchers include: John Branca, A.D. Cohen, Bernard Dirska, Gregory S. Ghon, G. Michael Hager, C. Scott Howard, Guy W. Metz, Margaret O. Plank, LeAnn Srogi, Richard F. Ward, and DGS. Existing data/slide descriptions have been included; however, no attempt was made to change the data/descriptions originally prepared by these researchers other than to correct typographical errors. These data appear as they were originally presented unless noted that modifications were made at a later date. Additional Notes The zoom tool allows one to focus on an area of interest. Click on an outcrop (sample) location to open a popup window containing the data for the selected sample(s). The popup window also includes thumbnail photomicrographs of the thin section in both plain polarized light and crossed polarized light. Click the thumbnail to open a full-size image. If interested in specific outcrops or thin sections, use the search tool to query by DGS outcrop ID, lithology, or address. Launch the Delaware Geological Survey Petrographic Data Viewer References Branca, J., 1979, Petrology and structure of the Glenarm Series and associated rocks in the Mill Creek area, Delaware: Newark, Delaware, University of Delaware, unpublished Master's thesis, 84 p. Cohen, A. D., 1964, Petrologic analysis of the gneisses at Windy Hills Bridge, Delaware: Newark, Delaware, University of Delaware, unpublished Geo402 class paper, DGS Sample/thin section record only. Dirska, B., 1990, Petrology and evolution of the plutonic igneous rocks of the Wilmington Complex, northeastern northeastern Delaware and southeastern Pennsylvania: Newark, Delaware, University of Delaware, unpublished Master's thesis, 227 p. Gohn, G.S., John, C.J., Hager, G.M., Niemann, N.L., Grundl, T.J., Bair, P.L., Dempsey, J.M., Ferris, L.A., and Lazzeri, J.J., 1974, Reconnaissance geology of the Mill Creek uplift, northeastern Delaware and southeastern Pennsylvania Piedmont: Newark, Delaware, University of Delaware, unpublished report, 23 p. Hager, G. M., 1976, Petrologic and structural relations of the crystalline rocks in the Hoopes Reservoir area, Delaware: Newark, Delaware, University of Delaware, unpublished Master's thesis, 79 p. Howard, C. S., 1984, Geological and geophysical investigations in the Wilmington Complex/Wissahickon Formation boundary area, Delaware Piedmont: Newark, Delaware, University of Delaware, unpublished Master's thesis, 258 p. Metz, G. W., 1988, The petrology of the cordierite-bearing gneisses near Montchanin, Delaware: Newark, Delaware, University of Delaware, unpublished senior thesis, 44 p. Plank, M. O., 1989,Metamorphism in the Wissahickon Formation of Delaware and adjacent areas of Maryland and Pennsylvania: Newark, Delaware, University of Delaware, unpublished Master's thesis, 111 p. Srogi, L., 1988, The petrogenesis of the igneous and metamorphic rocks in the Wilmington Complex, Pennsylvania-Delaware Piedmont: Philadelphia, Pennsylvania, University of Pennsylvania, unpublished Ph. D. dissertation, 613 p. Ward, R. F., 1958, Petrology and metamorphism of the Wilmington Complex Delaware adjacent Pennsylvania and Maryland: Philadelphia, Pennsylvania, Bryn Mawr College, unpublished Ph. D. dissertation, 103 p.Item Historical Coastline Changes of Cape Henlopen, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2001) Ramsey, K.W.; Wang, L.T.Coastlines are not static features. They are shaped by the daily effects of wind, current, and wave activity. Over time, a coastline may move landward due to relative sea-level rise or low sediment supply, or seaward due to relative sea-level fall or an overabundance of sediment. Perhaps the most striking example of shoreline movement in Delaware is at Cape Henlopen which has grown northward approximately one mile in the last 160 years. Maps and aerial photographs show these changes.Item Locating Ground-Water Discharge Areas In Rehoboth And Indian River Bays And Indian River, Delaware Using Landsat 7 Imagery(Newark, DE: Delaware Geological Survey, University of Delaware, 2008) Wang, L.T.; McKenna, T.E.; DeLiberty, T.L.Delaware’s Inland Bays in southeastern Sussex County are valuable natural resources that have been experiencing environmental degradation since the late 1960s. Stresses on the water resource include land use practices, modifications of surface drainage, ground-water pumping, and wastewater disposal. One of the primary environmental problems in the Inland Bays is nutrient over-enrichment. Nitrogen and phosphorous loads are delivered to the bays by ground water, surface water, and air. Nitrogen loading from ground-water discharge is one of the most difficult to quantify; therefore, locating these discharge areas is a critical step toward mitigating this load to the bays. Landsat 7 imagery was used to identify ground-water discharge areas in Indian River and Rehoboth and Indian River bays in Sussex County, Delaware. Panchromatic, near-infrared, and thermal bands were used to identify ice patterns and temperature differences in the surface water, which are indicative of ground-water discharge. Defining a shoreline specific to each image was critical in order to eliminate areas of the bays that were not representative of open water. Atmospheric correction was not necessary due to low humidity conditions during image acquisition. Ground-water discharge locations were identified on the north shore of Rehoboth Bay (west of the Lewes and Rehoboth Canal), Herring and Guinea creeks, the north shore of Indian River, and the north shore of Indian River Bay near Oak Orchard.Item Physiographic Regions of the Delaware Atlantic Coast(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Ramsey, K.W.; Schenck, W.S.; Wang, L.T.Item Selected Geomorphic Features of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Ramsey, K.W.; Schenck, W.S.; Wang, L.T.The shaded relief image on the left was created using 30-meter resolution Digital Elevation Models (DEMs). The DEMs were developed by John Mackenzie, University of Delaware College of Agriculture and Natural Resources Spatial Analysis Laboratory, from rasterized 1992-93 United States Geological Survey (USGS) Digital Line Graph (DLG) hypsography data. He also combined these data with zero-elevation contours extracted from 1989 Landsat TM Band 7 satellite imagery for coastal quadrangles. The image was digitally enhanced using a false sun angle of 45 degrees shining from the northwest to exaggerate the geomorphic features. In reality the Delaware Coastal Plain is not "mountainous," as it looks in this enhanced image. The hydrology layer was created using USGS 30 x 60 minute and 7.5 minute series DLG data. Municipal boundaries were created using the Delaware Municipal Boundary Framework Layer. Both maps are projected in Universal Transverse Mercator, Zone 18 (UTM 18) on the North American Datum 1983 (NAD83).