Research and Publications - Department of Geological Sciences
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Item Pseudocorax (Chondrichthyes, Lamniformes, Pseudocoracidae) in the Upper Maastrichtian phosphates of Khouribga Province, Morocco(Cambridge University Press, 2025-11-21) Egli, Hunter Chase; Goode, Benjamin; Rempert, Trevor; Rego, ChristopherA new species of Pseudocorax (Lamniformes, Pseudocoracidae), Pseudocorax heteroserratus n. sp., is described from the upper Maastrichtian phosphates of Morocco. This novel taxon is recognized by a large sample of isolated teeth collected from the upper Couche III layer at the Sidi Chennane quarry in the Oulad Abdoun Basin, Khouribga Province, Morocco. P. heteroserratus is differentiated from other Pseudocorax species by bearing a mesiodistally elongated tooth base, broad crown, and highly variable serrations. The variability in number and extent of serrations along the carinae ranges from completely absent to fully serrated and finely to coarsely serrated, raising speculation on broader Pseudocorax phylogenetics and as to whether the genesis of serrations within Pseudocorax occurred in a singular progressive event or rather from two distinct events. The morphological variability within the new species highlights the importance of large sample sizes in selachian odontological studies using isolated teeth.Item On Some Post-Eocene and Other Formations of the Gulf Region of the United States(The American Association for the Advancement of Science, 1906-03-30) Smith, Eugene A.Item Tertiary Phosphates in Alabama(American Association for the Advancement of Science., 1885-05-08) Smith, Eugene A.Item Underthrust Folds and Faults(American Journal of Science, 1893) Smith, Eugene A.Item Oxygen isotope composition of teeth suggests endothermy and possible migration in some Late Cretaceous shark taxa from the Gulf Coastal Plain, USA(Cambridge University Press, 2025-01-02) Comans, Chelsea M.; Tobin, Thomas S.; Totten, Rebecca L.We analyzed the oxygen isotope composition of biogenic apatite phosphate (δ18Op) in fossil tooth enameloid to investigate the paleoecology of Late Cretaceous sharks in the Gulf Coastal Plain of Alabama, USA. We analyzed six different shark taxa from both the Mooreville Chalk and the Blufftown Formation. We compared shark δ18Op with the δ18Op of a co-occurring poikilothermic bony fish Enchodus petrosus as a reference for ambient conditions. Enchodus petrosus tooth enamel δ18Op values are similar between formations (21.3‰ and 21.4‰ Vienna Standard Mean Ocean Water [VSMOW], respectively), suggesting minimal differences in water δ18O between formations. Most shark taxa in this study are characterized by δ18Op values that overlap with E. petrosus values, indicating they likely lived in similar hab itats and were also poikilothermic. Ptychodus mortoni and Cretoxyrhina mantelli exhibit sig nificantly lower δ18Op values than co-occurring E. petrosus (P. mortoni δ18Op is 19.1‰ VSMOW in the Mooreville Chalk; C mantelli δ18Op is 20.2‰ VSMOW in the Mooreville Chalk and 18.1‰ VSMOW in the Blufftown Formation). Excursions into brackish or fresh water habitats and thermal water-depth gradients are unlikely explanations for the lower P. mortoni and C. mantelli δ18Op values. The low P. mortoni δ18Op value is best explained by higher body temperature relative to surrounding temperatures due to active heating (e.g., mesothermy) or passive heating due to its large body size (e.g., gigantothermy). The low C. mantelli δ18Op values are best explained by a combination of mesothermy (e.g., active heating) and migration (e.g., from the Western Interior Seaway, low-latitude warmer waters, or the paleo–Gulf Stream), supporting the hypothesis that mesothermy evolved in lamniform shark taxa during the Late Cretaceous. If the anomalous P. mortoni δ18Op values are also driven by active thermoregulation, this suggests that mesothermy evolved independently in multiple families of Late Cretaceous sharks.Item Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru.Sandweiss, Daniel S.; Andrus, C. Fred. T.; Kelley, Alice R.; Maasch, Kirk A.; Reitz, Elizabeth J.; Roscoe, Paul B.Item Examining the potential of Pacific abalone as a novel high-resolution archive of upwelling in the California Current.Bassett, Christine N.; Andrus, C. Fred. T.Item Skeletal growth controls on Mg/Ca and P/Ca ratios in tropical Eastern Pacific rhodoliths (coralline red algae).Sletten, Hillary R.; Gillikin, David P.; Halfar, Jochen; Andrus, C. Fred. T.; Guzman, HectorItem A 7,000-year record of floods and ecological feedbacks in Weeks Bay, Alabama, USA.Minzoni, Rebecca T.; Parker, Lauren E.; Wallace, Davin J.; Lambert, William J.; Elliot, Emily A.; Andrus, C. Fred. T.Item Fundamental questions and applications of sclerochronology: community-defined research priorities.Trofimova, T.; Alexandroff, S.; Mette, M.; Tray, E; Butler, P.; Campana, S.; Harper, E.; Johnson, A.; Morrongiello, J.; Peharda Uljevic, M.; Schöne, B. R.; Andersson, C.; Andrus, C. Fred. T.; Black, B.; Buechell, M.; Carroll, M.; DeLong, K.; Gillanders, B.; Grønkjær, P.; Killam, D.; Pendergrast, A.; Reynolds, D.; Scourse, J.; Shirai, K.; Thebault, J.; Trueman, C.; de Winter, N. J.Item Subseasonal variations in marine radiocarbon reservoir age from pre-bomb Donax obesulus and Protothaca asperrima shell carbonate.Etayo-Cadavid, Miguel F.; Andrus, C. Fred. T.; Jones, Kevin B.; Hodgins, Gregory W. L.Item Sclerochronological basis for growth increment counting: a reliable technique for life-span determination of Crassostrea virginica from the Mid-Atlantic United States.Zimmt, J. B.; Lockwood, Rowan; Andrus, C. Fred. T.; Herbert, G. S.Item Gneiss Domes, Vertical and Horizontal Mass Transfer, and the Initiation of Extension in the Hot Lower-Crustal Root of a Continental Arc, Fiordland, New ZealandKepeis, Keith A.; Schwartz, Joshua; Stowell, Harold; Tulloch, AndrewItem The Farnham Peat Collection: A Subject Catalog of the Peat Research Materials in the Natural Resources Library(1990-08-04) Sandy, John H.; Hauck, Barbara H.; Hendrickson, Susan R.; Weber, Frances A.Item NRRI Library to House Materials Related to Copper-Nickel Study(1989-03-10) Sandy, John H.; Miller, PatriciaItem The Elusive Evidence of Volcanic Lightning(Nature Portfolio, 2017) Genareau, K.; Gharghabi, P.; Gafford, J.; Mazzola, M.; University of Alabama Tuscaloosa; Mississippi State UniversityLightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.Item Use of ESI-FTICR-MS to Characterize Dissolved Organic Matter in Headwater Streams Draining Forest-Dominated and Pasture-Dominated Watersheds(PLOS, 2015) Lu, YueHan; Li, Xiaping; Mesfioui, Rajaa; Bauer, James E.; Chambers, R. M.; Canuel, Elizabeth A.; Hatcher, Patrick G.; University of Alabama Tuscaloosa; Old Dominion University; Ohio State University; William & Mary; Virginia Institute of Marine ScienceElectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest-or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8-87.9%), with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S)) accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C = 0.7-1.5, O/C = 0.1-0.67), suggesting the predominance of allochthonous, terrestrial plant-derived DOM. Relative to the two pasture streams, DOM formulas in the two forest streams were more similar, based on Jaccard similarity coefficients and nonmetric multidimensional scaling calculated from Bray-Curtis distance. Formulas from the pasture streams were characterized by lower proportions of aromatic formulas and lower unsaturation, suggesting that the allochthonous versus autochthonous contributions of organic matter to streams were modified by pasture land use. The number of condensed aromatic structures (CAS) was higher for the forest streams, which is possibly due to the controlled burning in the forest-dominated watersheds and suggests that black carbon was mobilized from soils to streams. During 15-day biodegradation experiments, DOM from the two pasture streams was altered to a greater extent than DOM from the forest streams, with formulas with H/C and O/C ranges similar to protein (H/C = 1.5-2.2, O/C = 0.3-0.67), lipid (H/C = 1.5-2.0, O/C = 0-0.3), and unsaturated hydrocarbon (H/C = 0.7-1.5, O/C = 0-0.1) being the most bioreactive groups. Aromatic compound formulas including CAS were preferentially removed during combined light+bacterial incubations, supporting the contention that black carbon is labile to light alterations. Collectively, our data demonstrate that head-water DOM composition contains integrative information on watershed sources and processes, and the application of ESI-FTICR-MS technique offers additional insights into compound composition and reactivity unrevealed by fluorescence and stable carbon isotopic measurements.Item Recognition of a likely two phased extinction at the K-Pg boundary in Antarctica(Nature Portfolio, 2017) Tobin, Thomas S.; University of Alabama TuscaloosaThe southernmost Cretaceous-Paleogene (K-Pg) outcrop exposure is the well-studied exposure on Seymour Island, Antarctica. Deposition across the K-Pg boundary there is uninterrupted, and as a consequence the ammonite fossil record is commonly used to test statistical methods of evaluating mass extinctions to account for the incompleteness of the fossil record. Numerous detailed fossil data sets from Seymour Island, comprised dominantly of mollusks, have been published over the last 30 years, but in most cases have not received statistical treatment. Here a previously published statistical technique is modified, automated, and applied to all published macrofossil data sets available from Seymour Island. All data sets reveal likely evidence of two separate multi-species extinctions, one synchronous with bolide impact evidence at the K-Pg boundary, and another 45 +/- 15 meters (similar to 140-290 ky) below the boundary. The apparent earlier extinction primarily affects benthic mollusks, while the boundary extinction primarily affects ammonites. While there is no unique sedimentological change over the interval where the earlier extinction is identified, it is impossible to exclude the possibility that this pattern is stratigraphically controlled. The automation of this technique allows it to be applied easily to other large fossil data sets.Item Fractal nature of groundwater level fluctuations affected by riparian zone vegetation water use and river stage variations(Nature Portfolio, 2019) Sun, HongGuang; Gu, Xiufen; Zhu, Jianting; Yu, Zhongbo; Zhang, Yong; Hohai University; University of Wyoming; University of Alabama TuscaloosaGroundwater systems affected by various factors can exhibit complex fractal behaviors, whose reliable characterization however is not straightforward. This study explores the fractal scaling behavior of the groundwater systems affected by plant water use and river stage fluctuations in the riparian zone, using multifractal detrended fluctuation analysis (MFDFA). The multifractal spectrum based on the local Hurst exponent is used to quantify the complexity of fractal nature. Results show that the water level variations at the riparian zone of the Colorado River, USA, exhibit multifractal characteristics mainly caused by the memory of time series of the water level fluctuations. The groundwater level at the monitoring well close to the river characterizes the season-dependent scaling behavior, including persistence from December to February and anti-persistence from March to November. For the site with high-density plants (Tamarisk ramosissima, which requires direct access to groundwater as its source of water), the groundwater level fluctuation becomes persistent in spring and summer, since the plants have the most significant and sustained influence on the groundwater in these seasons, which can result in stronger memory of the water level fluctuation. Results also show that the high-density plants weaken the complexity of the multifractal property of the groundwater system. In addition, the groundwater level variations at the site close to the river exhibit the most complex multifractality due to the influence of the river stage fluctuation.