Department of Earth Sciences
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The Earth Sciences Department is part of the College of Earth, Ocean, & Environment. We have an excellent faculty with research strengths in coastal and marine geology and geophysics, surface processes and geomorphology, hydrogeology, geomicrobiology, Quaternary geology, paleobiology and micropaleontology, and environmental geophysics.
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- ItemScarps and ridges in southeastern Virginia and adjacent North Carolina(1974) Oaks, R.Q.; Coch, N.K.; Sanders, J.E.; Flint, R.F.
- ItemSaturated hydrocarbon material in sediments of the Delaware estuary as determined by gas chromatographic analyses(College of Marine Studies, University of Delaware, Newark, Del., 1975) Wehmiller, John F.; Lethen, MargaretThis report presents a preliminary interpretation of the analyses of hydrocarbon material in sediments of the Delaware Estuary as determined by solvent extraction, column chromatography, and gas-liquid chromatography. The specific focus has been on the saturated group of compounds isolated by silica gel chromatography. Approximately 35 stations (out of a total of 100 sampled localities) from Philadelphia to the bay mouth have been analyzed, and several stations have been reoccupied and reanalyzed following the oil spill associated with the Corinthos tanker explosion on January 31, 1975. Many of these "post-Corinthos" samples are discussed in the appendix to this report.
- ItemAmino acid racemization age estimates for Pleistocene marine deposits in the Eukeka-Fields Landing Area, Homboldt County, California(U.S. Department of the Interior Geological Survey, 1977) Wehmiller, John F.; Kennedy, George L.; Lajoie, Kenneth R.Amino acid enantiomeric (D/L) ratios in fossil Saxidomus samples from four localities in the Eureka - Fields Landing area of the Humboldt Bay region, California yield age estimates of 180,000 to 280,000 years for exposed and slightly deformed bay and estuarine deposits.
- ItemCorrelation and chronology of Pacific Coast marine terrace deposits of continental United States by fossil amino acid stereochemistry technique, evaluation, relative ages, kinetic model ages, and geologic implications(U.S. Department of the Interior Geological Survey, 1977) Wehmiller, John F.; Lajoie, Kenneth R.; Kvenvolden, Keith A.; Peterson, Etta; Belknap, Daniel F.; Kennedy, George L.; Addicott, Warren O.; Vedde, John G.; Wright, Robert W.Enantiomeric (D/L) ratios of six or more amino acids have been determined in Pleistocene mollusks from fifty-one terrace localities on the Pacific coast of the United States from Puget Sound, Washington, to San Diego, California. Samples have been selected for the purpose of evaluation of various aspects of the amino acid dating technique as well as for the application of the technique to unresolved chronologic problems. Samples with known stratigraphic relationships (upper and lower Pleistocene, Pliocene) have been examined to document the relationships between geologic age and extent of racemization. Most genera investigated exhibit the expected trend of increasing extent of racemization with increasing age, but some genera do not document this trend, probably because of contamination during diagenesis. Of all genera examined in this manner, the bivalve mollusk Saxidomus appears to be the most reliable.
- ItemU.S. Geological Survey Professional Paper 1067-E map(Washington : U.S. G.P.O., 1982) Mixon, R.B.; Szabo, B.J.; Owens, J.P.
- ItemGeology 106 Guidebook: Field trip through the Appalachians of Eastern Pennsylvania(Department of Geological Sciences, University of Delaware, 1985) Thompson, Allan M.
- ItemAmino acid racemization dating of some coastal plain sites, southeastern Virginia and northeastern North Carolina(University of Delaware, Newark, DE, 1985) Mirecki, JuneBivalve mollusks (g. Mercenaria and g. Anadara) have been analyzed from 4 southeastern coastal plain sites using the amino acid racemization (AAR) technique for correlation and age estimate purposes. As seen previously (Wehmiller and Belknap, 1982), a conflict exists between age estimates obtained by AAR and V-series methods at the Norris Bridge, VA locality. Here, V-series dating of coral yields a 187 ±20 KA age, while AAR methods suggest a 400 to 500 KA age. The following methods are employed to understand this discrepancy at the Norris Bridge site: 1). Analysis of standard samples to ensure uniform sample preparation and system operation; 2). Quantification of variation in Mercenari'a and Anadara samples for each field site; 3). Qualitative comparison of AAR behavior between Mercenaria and Anadara to assess suitability of Anadara for dating purposes; 4). Aminostratigraphic correlation of field sites using both genera, and 5). Estimation of AAR ages using the the non-linear model of Wehmiller and Belknap (1982). Standard samples analyzed for this study show relatively good preCISIon. Coefficients of variation (CVs) of D/L leucine values are 5.7% (ILC-A) and 9.1% (ILC-B). Overall, both ILC-A and -B show accuracy within 6% when compared to other University of Delaware analyses. Several valves of each genus were analyzed from all sites to determine field site precision. CVs for multiple Mercenaria samples from each site are as follows: Gomez Pit, VA (5.2%); New Light Pit, VA (7.0%); Moyock Pit, N.C. (8.8%) and Norris Bridge, VA (4.4%). CVs for Anadara samples are slightly higher, but comparable for each field site. No Anadara were analyzed from the New Light Pit locality. On the basis of an identical order of racemization rates (i.e. ASP2:ALA> LEU>VAL) and similar ASP/LEU values in both genera, Mercenaria and Anadara qualitatively show similar racemization behavior. 3 clusters of DjL leucine values have been discerned from these field site analyses. These D/L leucine values are used to correlate fossiliferous strata in the southeastern Virginia and northeastern North Carolina Using the non-linear kinetic model, these Coastal Plain. D/L values suggest the following ages: 0.21 to 0.25 (75 KA) and 0.530 (approximately 400 KA). D/L values ranging between 0.33 and 0.38 are tentatively estimated to be 100 to 200 KA in age.
- ItemGomez Pit Site "06045", 1987 Collection(1987) Wehmiller, John F.
- ItemGomez Pit site "06074", 1988 collection(1988) Wehmiller, John F.
- ItemSusquehanna River Field Trip: Brittle Strain and the Stresses that Caused it(Department of Geological Sciences, University of Delaware, 1988-10) Thompson, Allan M.
- ItemGeology 401 Central Pennsylvania Field Trip(Department of Geological Sciences, University of Delaware, 1988-11-05) Thompson, Allan M.
- ItemGomez Pit sites "06074" and "06076", 1989 collection(1989) Wehmiller, John F.
- ItemThe Palisade Sill(Department of Geological Sciences, University of Delaware, 1989-03-04) Thompson, Allan M.
- ItemNorthwestern area of Gomez Pit, 1990 collection (1990) Wehmiller, John F.
- ItemAminostratigraphy, geochronology and geochemistry of fossils from Late Cenozoic marine units in southeastern Virginia(University of Delaware, Newark, 1990) Mirecki, JunePaired Amino Acid Racemization (AAR) and Electron Spin Resonance (ESR) data have been obtained from individual mollusc valves (g. Mercenaria) collected from stratified nearshore deposits at three sites in southeastern Virginia (Gomez Pit, Norris Bridge and Yadkin Pit). AAR and ESR data are used here to define aminozones in the region, and to infer age relationships among these superposed aminozones. These data are compared to U-Th analyses of corals from both sites (Szabo, 1985). Age differences among aminozones are estimated using models of racemization kinetics. Previous workers have generally concluded that the lithologic section at Gomez Pit represents a single transgression followed by minor regression. However, AAR and ESR data indicate at least one unconformity in this transgressive sequence, representing approximately 100 ka. The uppermost aminozone lla is defined by a mean ALLO/ISO values of 0.141+/-0.026 (n = 55). Aminozone lla directly overlies aminozone llc (ALLO/ISO = 0.335+/-0.028; n = 19). Molluscs representing a third, lowest aminozone (lld; ALLO/ISO = 0.471+/-0.038; n = 9) are recognized, but taphonomic and ESR data suggest that lld molluscs in Gomez Pit may be reworked. At Norris Bridge, only aminozone lld (ALLO/ISO = 0.473+/-0.020; n = 5) is recognized. ESR age estimates for aminozone lla range from 93-125 ka (n = 4), in general agreement with a Stage 5 estimate of 75+/-5 ka from U-Th analyses of corals from the same unit. ESR age estimates of 220 and 262 ka were calculated from 2 shells showing ALLO/ISO = 0.33; these data support a Stage 7 or Stage 9 interpretation for aminozone llc. AAR kinetic models suggest an age $>$400 ka for aminozone lld shells, inconsistent with a 187+/-20 ka age from a solitary coral at Norris Bridge. Attempts to obtain age estimates using ESR have been unsuccessful. Shells representing excellent, good, fair and poor preservation conditions from Gomez Pit aminozone lla were compared to determine the effects of condition on precision of amino acid data. These data were used to test the hypothesis that leaching by groundwater selectively removes the most extensively epimerized (free) amino acids from the mollusc shell, thus lowering the ALLO/ISO value. No statistically significant difference in amino acid concentrations, amino acid fractions or ALLO/ISO values was found among these Gomez Pit shells representing different preservation characteristics.
- ItemThe Pleistocene Planktonic Foraminiferal Aminostratigraphy of Ocean Drilling Program Hole 625B in the Northeast Gulf of Mexico(University of Delaware, Newark., 1990) Johnson, Beverly J.Amino acid analyses were performed on four planktonic species of foraminifera and a mixed foraminiferal species assemblage through the Quaternary section of Ocean Drilling Program Site 625B in the northeast Gulf of Mexico. The extent of isoleucine epimerization in the individual species increased with time as the overall rate of epimerization decreased with time. Extents of epimerization among the species in increasing order are Globigerinoides ruber, Orbulina universa, Neogloboquadrina dutertrei and the Globorotalia tumida-menardii complex. The mixed foraminiferal species assemblage was found to epimerize at a rate intermediate to the limits delineated by Globigerinoides ruber and the Globorotalia tumida-menardii complex.
- ItemStructure of the Blue Ridge in the Harpers Ferry Area(Department of Geological Sciences, University of Delaware, 1992-11-07) Thompson, Allan M.
- ItemSusquehanna River Field Trip. Ductile deformation in an orogen: folds and foliations(Department of Geological Sciences, University of Delaware, 1993-10-16) Thompson, Allan M.
- ItemFoliations and superposed folding in the Maryland-Virginia Piedmont, Great Falls National Park(Department of Geological Sciences, University of Delaware, 1993-11-07) Thompson, Allan M.
- ItemGeology 106: Field Trip Across the Appalachian Orogenic Belt. April 30, 1984(Department of Geological Sciences, University of Delaware, 1994) Thompson, Allan M.