Abstracts with Programs - Geological Society of America

More documents

Recommendations

Info

SESSION NO. 28 suggest means by which further erosion and shallowing could be prevented, and potentially reversed. 28-26 BTH 26 Freeman-Ballew, Elizabeth [218722] PRELIMINARY LOSS-ON-IGNITION DATA FROM CRYSTAL LAKE, OHIO FREEMAN-BALLEW, Elizabeth, Earth and Environmental Sciences, Wright State University, Dayton, OH 45435-0001, freeman.48@wright.edu, DEUTER, Leigh H., Earth and Environmental Sciences, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 45435, and TEED, Rebecca, Department of Earth and Environmental Sciences, Wright State University, 260 Brehm Labs, 3640 Colonel Glenn Highway, Dayton, OH 45435 Crystal Lake located in Medway, Ohio (39°N 53’, 84°W 01’), is an 11 meter deep kettle lake, formed during the Wisconsinan glacial event, close to the glacial ice boundary. Lake sediment cores extending from 1130 to 2000 cm below the lake surface were collected in 2008. Loss of ignition (LOI) is a method used to estimate the amount of organic matter and carbonate in the sediment. The results from an LOI analysis, of the upper levels of the core indicate a high frequency variation in the percentage of organic material in the sediment (1200-1550cm) of 4 to 18% with an average of five to six fluctuations per meter. Previous studies of gastropod and diatom species indicate lake level change; perhaps these lake level changes affected the percentage of organic material. The current investigation includes: 1) LOI analysis of the remaining sediment (1650-2000cm), to determine if the variations continue or change in older sediments 2) radiocarbon dating of a wood fragment found at 1302cm 3) collaboration with researchers who are trying to understand the modern trophic status and groundwater system of the lake. Continued research at this site will enrich the overall understanding of the sedimentary history of the lake, while also shedding light on the paleoclimate of southwestern Ohio during the last glaciation. 28-27 BTH 27 Morrison, Sean M. [218779] INCISION AND LATERAL MIGRATION ALONG TERRACES OF THE LOWER CHIPPEWA RIVER VALLEY, WI, USA: A GPR INVESTIGATION MORRISON, Sean M. 1 , STRUVE, Matthew W. 1 , ROEGLIN, Lauren E. 2 , JOL, Harry M. 2 , FAULKNER, Douglas J. 3 , and RUNNING, Garry Leonard IV4 , (1) Departmet of Geography and Anthropology, University of Wisconsin Eau Claire, Eau Claire, WI 54702, morrissm@ uwec.edu, (2) Department of Geography and Anthropology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702, (3) Geography and Anthropology, University of Wisconsin, Eau Claire, WI 54701, (4) Geography and Anthropology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702 The Lower Chippewa River Valley in west-central Wisconsin displays numerous terraces formed by episodes of incision and followed by lateral migration. Sediments deposited during the lateral migration of the river are primarily composed of sand while the underlying sediments consist of a mix of sand and gravel deposited by glaciofluvial process as the paleo-Chippewa River aggraded during the late Wisconsinan. Using high resolution ground penetrating radar (GPR) data, the depth to which the Chippewa River laterally migrated following each episode of incision was determined. GPR data was collected along numerous terraces using Sensors and Software PulseEkko 100 and 1000 GPR systems while laser leveling was used to determine topographic changes. High frequency antennae were used to attain the level of detail needed to determine the depth of deposits related to lateral migration. Step size varied from 0.1 m to 0.5 m, while antennae separation ranged from 0.5 m to 1.0 m. Common midpoint surveys (CMP) were conducted and resulted with a near surface velocity of 0.10-0.11 m/ns at most sites. The radar facies of the top most depositional layer were examined in order to better understand the nature of the river during times of lateral migration. The reflections show horizontal to sub-horizontal, semi-continuous reflections to a depth of three to four meters. The radar stratigraphic analysis suggests a well-defined episode of incision followed by lateral migration [braided river process] on all investigated terraces. 28-28 BTH 28 Warbritton, Matthew J. [218377] 3-D MODELING ON THE EFFECTS OF BASELEVEL CHANGE ON RIVER DELTAS WARBRITTON, Matthew J. 1 , NILGES, Tayloy P. 1 , and LONDOÑO, Ana C. 2 , (1) Earth and Atmospheric Science Department, Saint Louis University, Saint Louis, MO 63103, mwarbrit@ slu.edu, (2) Earth and Atmospheric Sciences, Saint Louis University, 205 O’Neil Hall, 3642 Lindell Blvd, Saint Louis, MO 63108 Climate change may impart changes to river deltas and surrounding areas that may have a detrimental effect on coastal cities. Three dimensional models can be used to observe and predict changes in delta structure by changing parameters thought to be affected by climate change. Using an Em-4 stream table we will investigate the effects of varying parameters on the delta. We will be recording delta measurements and images to construct 3-D models in order to better understand and visualize the changes occurring to the deltas. Being able to control baselevel, sediment grain size, discharge, and other variables will allow us to conduct experiments addressing several different scenarios. We expect to find a significant change in delta progradation, number of lobes, and water cover over the delta with changes in baselevel. This research will have implications for understanding how the rise in baselevel may affect surrounding land and population areas due to flooding, possible changes in delta and stream patterns, and potential delta migration. 28-29 BTH 29 Cullen, Patrick [218528] ASYMMETRY OF LATE PENNSYLVANIAN GLACIO-EUSTATIC FLUCTUATIONS IN THE NORTH AMERICAN MIDCONTINENT CULLEN, Patrick1 , MILEWSKI, Stormy1 , BAUMANN, Eric Jr2 , ALGEO, Thomas J. 3 , MAYNARD, J. Barry4 , HERRMANN, Achim D. 5 , and HECKEL, Philip H. 6 , (1) Geology, University of Cincinnati, Cincinnati, OH 45221, cullenpj@mail.uc.edu, (2) Geology, University of Cincinnati, 5359 Little Turtle Dr, South Lebanon, OH 45065, (3) Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, (4) Department of Geology, University of Cincinnati, 345 Clifton Court, Cincinnati, OH 45221, (5) Geology & Geophysics, Louisiana State University, Baton Rouge, LA 70803, (6) Department of Geoscience, University of Iowa, Iowa City, IA 52242 The growth and decay of continental icesheets are highly asymmetric processes. During the Pleistocene, growth proceeded slowly (for up to 100 kyr) as ice mass built up over large areas, whereas decay proceeded quickly (~8-12 kyr) in response to global warming and icesheet disintegration. Similar patterns have been inferred for icesheets during pre-Pleistocene ice ages, but the evidence for differential rates of growth and decay is mainly circumstantial, e.g., the greater thickness of regressive versus transgressive facies in Upper Pennsylvanian cyclothems of the North American Midcontinent region. In this study, we quantified relative rates of eustatic regression (= icesheet growth) and transgression (= icesheet decay) in Midcontinent 64 2013 GSA Abstracts with Programs cyclothems on the basis of fine-scale (5-10-cm) cyclicity. Although the exact origin of this cyclicity is not known with certainty, it is unquestionably (quasi-)periodic and record the ~21-kyr orbital precession cycle. At any given locale on the Midcontinent Shelf, the onset and termination of black shale deposition marked, respectively, the transgression and regression of the chemocline. Relative rates of chemocline transgression and regression can be assessed based on the number of small-cycles below and above the maximum flooding surface of each cyclothem. We analyzed two Upper Pennsylvanian cyclothemic black shales, the Hushpuckney and Heebner, along transects from SW Iowa to central Oklahoma in order to reconstruct lateral changes in transgression-regression patterns. Although the number of cycles with each study unit varies somewhat as a function of position on the shelf, the transgressive and regressive portions of the black shale facies typically contain ~4±1 and ~8±2 cycles, respectively. On this basis, we infer that transgressions proceeded roughly twice as quickly as regressions. It should be noted that our conclusions are limited to only the late transgressive and early regressive stages of glacioeustatic cycles recorded by the black shale facies of cyclothems, and that rates of glacio-eustatic change during peak intervals of transgression and regression may have been different. Highresolution stratigraphic analysis of cyclothems, as undertaken in this study, has the potential to provide insights into contemporaneous icesheet dynamics. 28-30 BTH 30 Carnes, Jennifer L. [218367] CARBONATE LAKES ON BASALT FLOWS (MIOCENE KIRI KIRI FORMATION, LAKE TURKANA REGION, KENYA) CARNES, Jennifer L., Department of Geological Sciences, Ohio University, 316 Clippinger Labs, Athens, OH 45701-2979, jc458707@ohio.edu, GIERLOWSKI-KORDESCH, Elizabeth, Department of Geological Sciences, Ohio University, Athens, OH 45701-2979, TABOR, Neil J., Roy M. Huffington Department of Earth Sciences, Southern Methodist University, 3225 Daniel Ave, Dallas, TX 75275-0395, and RASMUSSEN, David Tab, Anthropology, Washington University, One Brookings Drive, St. Louis, MO 63130 The formation of lakes directly upon basalt flows is a rare phenomenon because of the high porosity and permeability of these volcanic rocks. Accumulation of lake sediments can only occur where the regional groundwater table intersects the lava flow; in this case, carbonate sedimentation occurs because of the weathering of Ca-rich feldspars as groundwater flows through and on the basalt. A modern example in Kenya is present at the volcanic area at the southern end of Lake Turkana with a Miocene example preserved approximately 85 km to the west within the Kiri Kiri Formation. Round outcrops of limestone occur within basalt depressions in this formation over a several square kilometer area. Each circular to semi-circular depression filled with limestone ranges on a scale from one meter to tens of meters wide. The thickness of these carbonate pond and lake deposits ranges from decimeters to several meters. Four main facies are present with many vertebrate and invertebrate fossils. Vertebrate remains include a monkey skull, crocodile scutes or scales, turtle shell fragments, and related bones. Invertebrate remains include a diversity of gastropods. Carbonate facies, as determined from thin section petrography, include fossiliferous massive micrite, microbial mounds, rhizolith-rich micrite, and debris-rich limestone. Textures indicate mostly subaqueous conditions with only very rare mudcracked horizons. The high groundwater table maintained these lakes and ponds, establishing a complex ecosystem. 28-31 BTH 31 Baumann, Eric [218536] INTENSIFIED WEATHERING AT THE PERMIAN-TRIASSIC BOUNDARY IN THE BALATON REGION OF HUNGARY BAUMANN, Eric Jr1 , CULLEN, Patrick2 , MILEWSKI, Stormy2 , and ALGEO, Thomas J. 3 , (1) Geology, University of Cincinnati, 5359 Little Turtle Dr, South Lebanon, OH 45065, baumanei@mail.uc.edu, (2) Geology, University of Cincinnati, Cincinnati, OH 45221, (3) Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013 The Permian-Triassic boundary (PTB) mass extinction, the largest biocrisis in Earth history, has been intensively investigated in marine and terrestrial sections in many parts of the world. However, marginal marine deposits, representing the interface between the marine and terrestrial environments, have received relatively little attention. In this study, we analyzed samples from the Balaton region of southwestern Hungary, representing marginal-marine facies (mainly finegrained limestone and dolostone) of latest Permian-Early Triassic age and open-marine facies (mainly fossiliferous wackestones and packstones) of Middle-Late Triassic age. Redox conditions were uniformly oxic throughout the study interval, as indicated by uniformly low concentrations of pyrite S (
(orthoconic cephalopod-like) fossils, as well as the brachiopods. The fossil assemblage, sedimentology and stratigraphy here appear to represent an equatorial shallow marine, nearshore to transitional (deltaic) tidal-influenced environment. Paleogeographic models place this area of Michigan on the southern coast of Laurentia during the Sauk I transgression. The moderate relief of the Proterozoic basement rock in this area most likely led to shallow embayments as the Sauk Sea transgressed onto the land, accentuated by tidal ebb and flow. We attempt to paint a clearer picture of the paleogeography of this portion of Laurentia during the Late Cambrian. 28-33 BTH 33 Moore, Rebecca J. [218699] PETROGRAPHIC ANALYSIS OF CAMBRIAN SANDSTONE CEMENT IN WESTERN WISCONSIN: IMPLICATIONS FOR THE COMPOSITION AND QUALITY OF FRAC SAND MOORE, Rebecca J., Geology, University of Wisconsin- Eau Claire, Eau Claire, WI 54702, moorerj@uwec.edu, RASMUSSEN, Amy K., Geology, University of Wisconsin - Eau Claire, Eau Claire, WI 54702, MAHONEY, J. Brian, Department. of Geology, University of Wisconsin Eau Claire, Eau Claire, WI 54702, and SYVERSON, Kent M., Dept. of Geology, University of Wisconsin, Eau Claire, WI 54702 Industrial sand mining has been expanding rapidly in western Wisconsin as demand for frac sand has increased. Concerns have been expressed about the potential for dust from the mining process causing non-occupational silicosis. Because the sand grains are large and hard, most respirable dust is likely derived from the sandstone cement. The purpose of this study is to use petrographic analysis to determine the cement mineralogy for major sandstone units in western Wisconsin. Samples have been collected from the Mount Simon, Wonewoc, Jordan, and St. Peter Formations (Cambrian Period, listed from oldest to youngest) in western Wisconsin. Samples were cut, impregnated with epoxy, and made into polished thin sections. Thin sections were examined using a petrographic microscope. Standard point counting and photomicrograph techniques are used to determine the mineralogy and relative percentages of the grains, cement, and voids. Qualitative observations (11 thin sections thus far) for each formation reveal authigenic K-spar, hematite, and quartz cements. The most abundant cement is authigenic K-spar, and the majority of samples have high porosity and little cement. Mount Simon Fm. sandstone (the oldest unit) contains large amounts of hematite and authigenic K-spar cement, with or without sericite. Wonewoc Fm. cement compositions vary, but abundant hematite and authigenic K-spar are present throughout the formation. Jordan Fm. cements differ markedly. Some rocks are primarily cemented by calcite. One sample from the upper Jordan Fm. is completely cemented with quartz, which has eliminated primary porosity and makes the rock extremely difficult to disaggregate and process. St. Peter sandstone has polycrystalline quartz grains rimmed with minor amounts of hematite and authigenic K-spar. A more extensive suite of samples is currently being analyzed. Quantitative results will presented at the meeting. The relative abundance of K-spar and hematite cements should reduce the concentration of crystalline silica in the respirable dust fraction. Also, multiple generations of cement and the high porosity values suggest repetitive cycles of cementation and diagenesis. 28-34 BTH 34 Kunz, Stephen E. [218784] SEQUENCE STRATIGRAPHY OF THE TYLER FORMATION (LOWER PENNSYLVANIAN/ MORROWAN) IN THE WILLISTON BASIN, NORTH DAKOTA KUNZ, Stephen E. 1 , SANDS, Jonathan1 , MARKS, Adam1 , MCMULLEN, John1 , and LEONARD, Karl W. 2 , (1) Anthropology and Earth Science, Minnesota State University Moorhead, 1104 7th Avenue South, Moorhead, MN 56563, kunzst@mnstate.edu, (2) Anthropology and Earth Science, Minnesota State Univsity Moorhead, 1104 7th Avenue South, Moorhead, MN 56563 This research is being done because Carboniferous rocks in North America are commonly cyclical (repeating lithofacies) because of changing climate conditions resulting in sea level changes during an “Icehouse” world. The Tyler Formation (Upper Carboniferous: Morrowan) occurs in the Williston Basin of Western North Dakota. It contains meter-scale cycles of repeating lithofacies. A sequence stratigraphic analysis of this formation would improve temporal and spatial resolution of this interval, as well as provide environmental and climatic significance to the nature of the cycles. The examination of core samples and well logs of the Tyler Formation examined along multiple transects from the basin center to the edges has shown cyclical lithofacies patterns repeating throughout the formation. These cycles begin with calcareous mudstones overlying a brecciated carbonate, then show carbonaceous shales and interbedded mudstones and limestone, and are capped with a brecciated carbonate interval. Lower cycles contains fossils (inarticulate brachiopods, bivalves) that indicate more restricted or shallow marine conditions, whereas middle and upper part fossils (crinoids, brachiopods, bryozoans) indicate more open-marine conditions. The lower cycles indicate a transgressing sea, whereas the middle and upper cycles occur above a maximum flooding surface or horizon. It’s expected that the middle and upper Tyler cycles will show greater lateral basin extent than the lower cycles. An enhanced stratigraphic framework is expected from this analysis, which will aid in future studies of fossil distribution patterns of the Tyler, may provide more insight into the climatic conditions of the Carboniferous in the Williston Basin, and improve the economic development of this formation. 28-35 BTH 35 White, Nathan [218368] SIGNIFICANCE OF LATE TRIASSIC CHARCOAL, AND LATE TRIASSIC AND LATE JURASSIC WOOD PETRIFICATION PROCESSES AND MINERALOGY, SOUTH-CENTRAL UTAH WHITE, Nathan, Geology, Augustana College, 639 38th St, Rock Island, IL 61201, nathanwhite@augustana.edu The Late Triassic Chinle Formation and Late Jurassic Morrison Formation crop out extensively near the town of Hanksville, Utah, and contain an abundance of well-preserved petrified wood. Enclosing rock types include siltstones, sandstones, conglomeratic sandstones, and conglomerates. Petrified wood samples were collected and analyzed using thin section microscopy and x-ray fluorescence spectrometry (XRF) in order to describe the petrification processes and mineralogy of the samples. Of particular interest is the presence of a nearly complete charcoal rind encasing one of the in-situ petrified logs. Triassic-aged charcoal is extremely rare, not only in Utah, but throughout the world. Due to the rarity of Triassic charcoal, scanning electron microscopy (SEM) was used in order to validate that the sample was indeed charcoal. SEM analysis revealed structures that are indicative of charcoal, even after being mineralized, without a significant amount of silica like the petrified log it encased. All petrified wood samples show a combination of replacement and impregnation, however, Triassic petrified wood shows mostly replacement of cell walls by silica and other accessory minerals probably due to high wood decay rates, whereas Jurassic petrified wood shows mostly cell impregnation by silica and other accessory minerals due to lack of wood decay. SESSION NO. 28 28-36 BTH 36 Milewski, Stormy [218385] THE NORTH AMERICAN STRATIGRAPHIC RECORD OF LATE PENNSYLVANIAN GLACIO- EUSTASY MILEWSKI, Stormy1 , CULLEN, Patrick1 , BAUMANN, Eric Jr2 , ALGEO, Thomas J. 3 , MAYNARD, J. Barry4 , HERRMANN, Achim D. 5 , and HECKEL, Philip H. 6 , (1) Geology, University of Cincinnati, Cincinnati, OH 45221, sladesl@mail.uc.edu, (2) Geology, University of Cincinnati, 5359 Little Turtle Dr, South Lebanon, OH 45065, (3) Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, (4) Department of Geology, University of Cincinnati, PO Box 210013, Cincinnati, OH 45221, (5) Geology & Geophysics, Louisiana State University, Baton Rouge, LA 70803, (6) Department of Geoscience, University of Iowa, Iowa City, IA 52242 During the Late Paleozoic Ice Age (LPIA), the Southern Hemisphere continent of Gondwana was heavily glaciated. However, the number and size of continental icesheets then in existence has been a matter of debate. The Midcontinent region of North America provides a potentially detailed record of changes in continental ice volume during the LPIA in the form of glacio-eustatic fluctuations. The Midcontinent was extensively flooded during highstand intervals (= ice-volume minima) and largely subaerially exposed during lowstand intervals (= ice-volume maxima), indicative of regular changes in continental ice mass thought to have been driven mainly by the Earth’s ~400-kyr long-eccentricity orbital cycle (Heckel, 1986, Geology, 14:330-334). We analyzed compositional variation through the Edmonds drillcore from northeastern Kansas, which spans the ~6-Myr-long interval from the mid-Desmoinesian through early Virgilian. This core contains 15 to 20 major cyclothems that record regular fluctuations in continental ice mass, representing one climate mode. Additionally, the core contains two thick siliciclastic intervals, comprised mainly of the Tacket and Weston shales, that represent extended lowstand intervals coinciding with the Desmoinesian-Missourian and Missourian-Virgilian stage boundaries, respectively. Each of these lowstand intervals contains several lithologic cycles documenting the continued influence of the 400-kyr orbital period. On this basis, we calculate that each lowstand interval lasted ~1.2 to 1.6 Myr. These lowstand intervals represent a second climate mode characterized by a lesser volume of continental ice, presumably due to melting of one or more icesheets in the Southern Hemisphere, relative to the highstand intervals that comprise the majority of the study interval. An analysis of this type, if extended over a wider stratigraphic interval, has the potential to provide a highly detailed record of changes in continental ice volume during the LPIA. 28-37 BTH 37 Meidlinger-Chin, Vernon [218390] BRAINCASE AND ENDOCRANIAL ANATOMY OF CRYOLOPHOSAURUS ELLIOTI (DINOSAURIA: THEROPODA) FROM THE EARLY JURASSIC OF ANTARCTICA MEIDLINGER-CHIN, Vernon, Geology, Augustana College, 3401 6th Avenue, Rock Island, IL 61201, vernonmeidlinger-chin09@augustana.edu Cryolophosaurus ellioti, a theropod dinosaur discovered in 1991, represents both the most complete dinosaur skeleton from Antarctica and the largest theropod from the Early Jurassic. Previous studies of the anatomy of Cryolophosaurus have focused on the postcranial anatomy and the bony aspects of the skull (Smith et al., 2007). No research has hitherto been conducted on the soft tissue anatomy of the brain. The holotype skull contains a nearly complete and undistorted cranial cavity, roughly approximating the shape and size of the living brain. Through the use of noninvasive CT scanning methods, we have created a digital endocast, which forms the basis of this study. This research provides a detailed comparative anatomical description of the braincase and endocranial anatomy of Cryolophosaurus, including the position of the cranial nerves, the angles of the pontine and cephalic flexures, and relative position of the major lobes. These data allow us, for the first time, to estimate the intelligence of Cryolophosaurus through calculations of encephalization quotient. Additionally, the introduction of phylogenetically informative endocast features clarifies the position of Cryolophosaurus within the theropod evolutionary tree; the dissimilarity of the endocast of Cryolophosaurus to those of Allosauroids and Coelurosaurs suggests that Cryolophosaurus occupies the basal position in Theropoda hypothesized by Smith et al. (2007). Thus, this research reveals new behavioral, paleobiological, and phylogenetic insights of Cryolophosaurus, with implications for the rest of Theropoda. 28-38 BTH 38 Fisher, Elizabeth A. [218454] CHARACTER ANALYSIS OF THEROPODA: A BRIEF STUDY CONFINED TO BRAINCASE CHARACTERS AND FOCUSING ON BASAL TAXA FISHER, Elizabeth A., Geology, Augustana College, 639 38th St, Rock Island, IL 61201, elizabethfisher09@augustana.edu Phylogenetic study of basal Theropoda has largely been ignored historically due to a paucity of specimens, but recent discoveries of many basal theropods and development of new technologies have encouraged a new interest in the study of these early theropods. Because paleontology is limited by the specimens available for study, the effort to collect more data often results in the attempt to find and use as many characters as possible in phylogenetic studies. This study arises from an interest in assisting researchers in the use of braincase characters for their analyses. Until recently, braincases where considered to be conservative and of not much use for phylogenetic studies. In this study, 51 braincase characters derived from 3 recent phylogenetic studies (Carrano, Benson, and Sampson 2012; Smith, et al. 2007; Turner, et al. 2007) were analyzed by tracing the character history in the phylogenetic program Mesquite against a tree constructed from the aforementioned papers. This analysis aims to identify characters falling into 1 of 3 groups: 1) characters which support this phylogeny, 2) characters which contradict the hypothesized relationships between taxa or suggest that the characters reflect environmental rather than genetic constraints, and 3) characters which require a more complete scoring to provide information on the type of pattern reflected by the character history. At least 16 characters are possible synapomorphies or generally support the tree and at least 5 characters seem to be contrary to the relationships hypothesized in the tree. 28-39 BTH 39 Yeider, Lindsey [218427] A NEW METHOD OF AGE DETERMINATION OF MAMMUTHUS COLUMBI YEIDER, Lindsey, Geology, Augustana College, 639 38th St, Rock Island, IL 61201, lindseyyeider09@augustana.edu Numerous hypotheses have been proposed as to the aging of ancient proboscideans, namely Mammuthus columbi, the Columbian mammoth. Of the proposed hypotheses, none has been proven in terms of accuracy. These methods leave a large margin of error resulting from application to a large range of species, in particular their use for fossil assemblages that may be missing specific anatomical features used for age determining methods. Richard Law’s (1966) work on African Elephant Age (AEY) and Sylvia Sikes’ (1966a) foramen mentale hypothesis employ measurements and visual comparisons to make rough estimates about the ages of Mammuthus columbi, but these methods may only be used when the lower mandible is present. My research introduces another technique that may prove to be more accurate and less destructive. It focuses on measurements of Columbian tusks in comparison with lower mandibular 2013 GSA North-Central Section Meeting 65
Page 1 and 2:
SESSION NO. 1, 8:00 AM Thursday, 2
Page 3 and 4:
structures, isolated sink-fills, an
Page 5 and 6:
3-10 11:20 AM Phillips, Andrew C. [
Page 7 and 8:
NaCl+KCl+HCl+H 2 O. Sulfide mineral
Page 9 and 10:
7-2 BTH 2 Miller, Kurtz K. [218056]
Page 11 and 12:
8-10 BTH 14 Rivera, Alexei A. [2180
Page 13 and 14: deposition as a function of the afo
Page 15 and 16: SESSION NO. 12, 1:30 PM Thursday, 2
Page 17 and 18: Because of this, the US Forest Serv
Page 19 and 20: 14-5 2:50 PM Hobbs, Trevor [218481]
Page 21 and 22: 15-6 3:30 PM Rudge, David W. [21786
Page 23 and 24: ecognizing additional post-cranial
Page 25 and 26: leakage. This study aims to use two
Page 27 and 28: Be Part of the 125th Anniversary Ce
Page 29 and 30: Sponsors Sapphire Level Topaz Level
Page 31 and 32: Kal-Haven Trail 9TH ST 10TH ST M43
Page 33 and 34: Paleontology Society Get-together w
Page 35 and 36: University, heather .petcovic@wmich
Page 37 and 38: Schedule of Events EvEnt timE Locat
Page 39 and 40: EvEnt timE Location T15. Paleontolo
Page 41 and 42: 3-2 8:20 AM Fisher, Timothy G.*; Bl
Page 43 and 44: sEssion no. 10 T6. Quaternary Time
Page 45 and 46: 16-9 4:35 PM McAfee, Robert K.*: on
Page 47 and 48: sEssion no. 24 T5. Quaternary Resea
Page 49 and 50: (miocEnE KiRi KiRi foRmation, LaKE
Page 51 and 52: 20-5 BTH 26 Lee, Charlotte I. [2187
Page 53 and 54: To identify areas in the watershed
Page 55 and 56: SESSION NO. 24, 8:00 AM Friday, 3 M
Page 57 and 58: 25-5 9:20 AM Gebrehiwet, Tsigabu [2
Page 59 and 60: distribution of P and other element
Page 61 and 62: the leading edges of an artificial
Page 63: as geology, ecology, biology, and r
Page 67 and 68: alluvium. Usually a distinctive dar
Page 69 and 70: 31-7 3:50 PM Wagner, Zachary C. [21
Page 71 and 72: 32-7 3:30 PM Martin, Nicholas [2186
Page 73 and 74: in the past, are multiplied by 50 y
Page 75 and 76: Crane, Renee 21-5* Crisp, Alexis A.
show all

Abstracts with Programs - Geological Society of America

Create successful ePaper yourself

Delete template?

Save as template?