DOCSLIB.ORG

Quaternary Nonglacial Geology : Conterminous US

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Quaternary Nonglacial Geology : Conterminous US HAMEjAIdR/k4W' U 1980 1989 The Geology of North America Volume K-2 QuaternaryNonglacial Geology: Conterminous U.S. Edited by Roger B. Morrison Morrison and Associates 13150 West Ninth Avenue Golden, Colorado 80401 t234oo051o(0 1991 931,041090035 9303 6 FDR 4ASTE TDR U ,rWRSITYOF NEVADAS LAS VEIM WI-li LBRARY 6-, Acknowledgment Publication of this volume, one of the synthesis volumes of The Decade of North American Geology Project series, has been made possible by members and friends of the Geological Society of America, corporations, and government agencies through contributions to the Decade of North American Geology fund of the Geological Society of America Foundation. Following is a list of individuals, corporations, and government agencies giving and/or pledging more than $50,000 in support of the DNAG Project: Amoco Production Company Pennzoil Exploration and ARCO Exploration Company Production Company Chevron Corporation Phillips Petroleum Company Cities Service Oi and Gas Company Sbell Oil Company Diamond Shamrock Exploration Caswell Saver Corporation Standard Oil Production Company Oryx Energy Company (formerly Exxon Production Research Company Sun Exploration and Production Getty Oil Company Company Gulf Oil Exploration and Production Superior Oil Company Company Tenneco Oil Company Paul V. Hoovler Texaco, Inc. Kencon Minerals Company Union Oil Company of California Kerr McGee Corporation Union Pacific Corporation and Marathon Oil Company its operating companim Maxus Energy Corporation Union Pacific ReOOuMcs company McMoRan 0i and Gas Company Union Pacific Railroad Mobil Oi Corporation Company Occidental Petroleum Corporation Upland Ilndusuries Corporation US. Department of Energy Data *1991 by The Geological Society of America, Inc= Lxary of Congress Catalogtng-ln-Publication All rights reserved. Quaternary nonglacial geology : conterminous US. / edited by Roger B. Mo-rison. p. an. - (The Geology of North America; v. K-2) materials aubject to thiso pyoty and included . Includes bibliographical references and index. n30J110 yslume may bpoboxcoped fixr thedoncoorndrcial ISBN 0-8137-5215-9 in ientiUicoreductiionalsed adv'ainCcM'L 1. Geology, Stratigraphic-Quaternary. Z Geology-United States. L Morrison, Roger B (Roger Barron), 1914- . H.Series. DAp ht is not caimed on any material prepared, QE696.Q336 1991 arc sovernmntereiployees within thescope oftheir b 551.7'9'0973-dc2O 91-23046 aP bployment. Published by The Geological Society of America. In= 3300 Penrose Place, P.O. Box 9140, Boulder. Colorado g3030 Printed in USA. Cover Photo: East bluff of the Walker River viewed from middle of Weber the Eetza Alloformation (130-350 ka) in Lake Lahontan's northern aubbasins. gravel Damn At least two million yeams of Lake Lahontan lacutrine and subaerial history Below another unconformity is 6 to 10 m of darker gray, chiefly lacustrine are ahown here in about 42 m of atrata in the Walker Like basin, the aouthern and sand (the upper pre-Eetza unit of Morrison and Davis, 1984b, p. 24, which most of Lake Lahontan's aubbasirs The top 6 i (light gray and light yellowish contains the I Ma Glass Mountain G tephra layerý Beneath a marked erosional gray) are lacustrine gravel and sand of the middle member of the Sehoo Allofor unconformity and extending to below the modem flood plain of the Walker River mation (about 13 ka) unoonformably overlying eolian and slopewash sand bear is 20+ m oftan-gray alluvial gravel and and intercalated with many palemols--a ing the Wyemaha Geosol (35-130 ka). Beneath another unconformity is 9 to unit considerably older than the Lovelock Alloformation in the northern basins. 10 m of medium to pale gray lazustrine gravel, aand, and salt equivalent to parts of Photo by R. B. Morrison. 10 9 8 7 6 5 4 3 2 1 ii .4 iv Contents K.Ar dauing of Quaternary olcanwc rocks ....................................... 49 P. L. Damon Fission-track dating ..................................................... 53 C. W. Naescv and N. D. Namser Conventionaluranium-serles and uranium-trenddating ............................... 55 B.J. Szabo and J. N. Rosholt Paleomagneticdating .................................................... 60 J. C. ddicoast Th7emo/-inescence dating ................................................ 61 S. L Forman and M. N. Machette Amino aid geochronology of foil mollusks ...................................... 65 D. L. Muhs 4. Quaternaryvolcanism in the western conterminous United States ..................... 75 R. G. Luedke and R. L. Smith 5. Quaternarytephrochronology ................................................... 93 A. M. Sama-Wojcicki and J. 0. Davis 6. Tephrochronologiccorrelation of upper Neogene sediments along the Pacific margin, conterminous United States ................................... 117 A. M. Sarna-Wojcicki, K. R. Lajoie, C. E. Meyer, D. P. Adam, and H. J. Rieck REGIONAL CHAPTERS 7. Quaternarygeology of the Pacific margin ........................................ 141 W. R. DuprE, R. B. Morrison, H. E. Clifton, K. R. Lajoie, D. J. Ponti, C. L Powell II, S. A. Mathieson, A. M. Sarna-Wojcicki, E. L. Leithold, W. R. Lettis, P. F. McDowell, T. K. Rockwell, J. R. Unruh, and R. S. Yeats Imtroducion ......................................................... 141 W. RLDupre and H. E.CMifton Quaternarycoas andshatow-mrine facies sequenc= Northern Ca/ifornia and die Pac#1c Northwest .................................... 143 H. E. Clifton and E. L Leithold Quaernary.gmradgwkp and geomorphic surfaces of de Wruilamerte Valley. Oregon................................................. 156 P. F. McDowdl Qaernarygeolov of the Great Vaet. Californu ................................. 164 W. f. Leuti and J. R. Unruh Quaternarygeology of te So-them CaliforniaCoast Ranges .......................... 176 W. R. Duprh Quaterniaygeology of the Ventura and Los Angeles basm Cahjbnia .......................................................... 185 R.I Yeats and T. K. Rockweil The Geology of North America Vol. K-2. Quaternarv Nonglactal Geology. Conterminous US. The Geologicai Society of Amenca. 1991 Chapter 3 Dating methods applicableto the Quaternary John N. Rosholt* US GeologicalSurvey. MS 963. Box 25046. Denver FederalCenter. Denver. Colorado 80225 Steven M. Colman US GeologicalSurvey. Woods Hole. Massachuseas 02543 Minze Stuiver Departmentof GeologicalSciences and Quaternarv Research Center. Universuty of Washington, Seattle, Washington 98195 Paul E. Damon Departmentof Geosciences. Universaty of Arizona. Tucson. Arizona 85721 Charles W. Naeser. Nancy D. Naeser, Barney J. Szabo. and Daniel R. Muhs US GeologicalSurvey, MS 424, Box 25046. Denver FederalCenter. Denver, Colorado 80225 Joseph C. Liddicoat Universigv of Ca'fornia,Santa Cruz California95064 Steven L Fornan Institute of Arctic and Alpine Research and Departmentof GeologicalSciences. University of Colorado.Boulder, Colorado 80309 Michael N. Machette and Kenneth L Pierce U.S GeologicalSurvey, MS 913. Box 25046, Denver Federal Center.Denver. Colorado 80225 SUMMARY OF QUATERNARY ments and should not be considered definitive; the entries for DATING METHODS applicability, age range, and optimum resolution are particularly interpretive. Details concerning assumptions, analytical tech Steven M. Colman and Kenneth L Pierce niques, uncertainties, and interpretations should be obtained from specialized references using the key references in Plate 2 as a INTRODUCTION AND COMPILATION OF guide. The dating methods described range from well-known and QUATERNARY DATING METHODS established techniques to experimental procedures whose results are subject to considerable interpretation. A wide variety of dating methods are used in Quaternary Key references included on Plate 2 are intended as an entry research. and each method has many applications and limitations. into the vast literature on dating methods-, space prohibits a more Because of this variety, we cannot discuss the applications and complete listing. We have emphasized recent review papers and limitations of all methods here. The more versatile and widely notable examples of applications as sources of additional refer used methods, including 14C, K/Ar, fission-track, U-series, pa ences and information. Dating methods discussed in other leomagnetism, thermoluminescence, and amino acid dating are sections of this chapter are indicated by asterisks in the summary treated more comprehensively in this chapter than other methods table. The first five references are reviews or edited volumes that that are shown on the summary chart. The summary chart is discuss Quaternary dating methods in general; references 6-11 provided here to give an overview of dating work and research are edited volumes that focus on individual methods or closely for the Quaternary. related methods. In the interest of brevity and clarity, we have not This summary consists mainly of a table (Plate 2) that is cited individual papers in these edited volumes. Some dating modified and updated from Colnan and Pierce (1977, Plate I, methods are based on fundamental geological principles, such as ref. 66). The table isintended as an overview and concise guide to stratigraphy, for which references are deemed unnecessary here. Quaternary dating methods. It contains many subjective judg- For the purpose of our discussion and summary table, it is useful to classify dating methods, which can be done in a variety of ways. Perhaps the simplest classification is one that groups methods that share similar assumptions, procedures, or applica- Rmholt. J. N., Columan. S.
Load more

Recommended publications
  • QUATERNARY GEOLOGIC MAP of AUSTIN 4° X 6° QUADRANGLE, UNITED STATES
    QUATERNARY GEOLOGIC MAP OF AUSTIN 4° x 6° QUADRANGLE, UNITED STATES QUATERNARY GEOLOGIC ATLAS OF THE UNITED STATES MAP I-1420 (NH-14) State compilations by David W. Moore and E.G. Wermund, Jr. Edited and integrated by David W. Moore, Gerald M. Richmond and Ann Coe Christiansen 1993 NOTE: This map is the product of collaboration of the Texas Bureau of Economic Geology and the U.S. Geological Survey, and is designed for both scientific and practical purposes. It was prepared in two stages. First, the map and map explanations were prepared by the State compiler. Second, information on the map was integrated with that of adjacent maps, locally supplemented, and related to a uniform map symbol classification by the editors. Map unit descriptions were edited, supplemented, and coordinated with those of other maps of this series so that individual unit descriptions are applicable throughout both this map and all other maps of the series. Problems of mapping or interpretation in different areas were resolved by correspondence to the extent possible; most simply reflect differences in available information or differences in philosophies of mapping and serve to encourage further investigation. Less than forty percent of the surficial deposits of the United States have been mapped and described. Traditionally, mapping of surficial deposits has focused on glacial, alluvial, eolian, lacustrine, marine, and landslide deposits. Slope and upland deposits have been mapped in detail only in restricted areas. However, an enormous amount of engineering construction and many important problems of land use and land management are associated with regions that have extensive slope and upland deposits (colluvium and residuum, for example).
    [Show full text]
  • Insights Into the Thermal History of North-Eastern Switzerland—Apatite
    geosciences Article Insights into the Thermal History of North-Eastern Switzerland—Apatite Fission Track Dating of Deep Drill Core Samples from the Swiss Jura Mountains and the Swiss Molasse Basin Diego Villagómez Díaz 1,2,* , Silvia Omodeo-Salé 1 , Alexey Ulyanov 3 and Andrea Moscariello 1 1 Department of Earth Sciences, University of Geneva, 13 rue des Maraîchers, 1205 Geneva, Switzerland; [email protected] (S.O.-S.); [email protected] (A.M.) 2 Tectonic Analysis Ltd., Chestnut House, Duncton, West Sussex GU28 0LH, UK 3 Institut des sciences de la Terre, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland; [email protected] * Correspondence: [email protected] Abstract: This work presents new apatite fission track LA–ICP–MS (Laser Ablation Inductively Cou- pled Plasma Mass Spectrometry) data from Mid–Late Paleozoic rocks, which form the substratum of the Swiss Jura mountains (the Tabular Jura and the Jura fold-and-thrust belt) and the northern margin of the Swiss Molasse Basin. Samples were collected from cores of deep boreholes drilled in North Switzerland in the 1980s, which reached the crystalline basement. Our thermochronological data show that the region experienced a multi-cycle history of heating and cooling that we ascribe to burial and exhumation, respectively. Sedimentation in the Swiss Jura Mountains occurred continuously from Early Triassic to Early Cretaceous, leading to the deposition of maximum 2 km of sediments. Subsequently, less than 1 km of Lower Cretaceous and Upper Jurassic sediments were slowly eroded during the Late Cretaceous, plausibly as a consequence of the northward migration of the forebulge Citation: Villagómez Díaz, D.; Omodeo-Salé, S.; Ulyanov, A.; of the neo-forming North Alpine Foreland Basin.
    [Show full text]
  • The Los Medaños Member of the Permian (Ochoan) Rustler Formation
    The Los Medaños Member of the Permian (Ochoan) Rustler Formation by Dennis W. Powers, HC 12 Box 87, Anthony, TX 79821; and Robert M. Holt, Dept. of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM 87801 Abstract We propose Los Medaños Member as the formal name for the lower part of the Upper Permian (Ochoan) Rustler Formation, below R31E the Culebra Dolomite Member, in the north- ern Delaware Basin. The stratotype is at the exhaust shaft of the Waste Isolation Pilot Exhaust Plant (WIPP) site in sec 20 T22S R31E, Eddy shaft T22S County, New Mexico. The name is derived from the nearby sand dune field (Los Meda- ños) and the quadrangle map of the same WIPP site name. Cores of the Los Medaños from WIPP studies correspond to the exhaust-shaft Los Medanos~ geology, though larger features revealed in T23S the shaft must be inferred. Geophysical log signatures permit regional correlations and interpretation of lithology. Outcrops of this Midland unit are poorly exposed and have been little Basin studied. Recent radiometric ages from cor- Hobbs relative units in the Texas panhandle sug- San Simon Study gest that the top of the Rustler is near the area Permian–Triassic boundary. Carlsbad The stratotype consists of 34.4 m of silici- WIPP Central Basin clastics, halitic mudstones, muddy halite, Nash Draw and sulfates (mainly anhydrite). Bedding, Platform invertebrate fossil remains, and bioturba- New Mexico Midland tion indicate a saline lagoon with connec- Texas tions to open marine water, in contrast to the Odessa shallow-water, desiccating evaporite cycles of the underlying Salado Formation.
    [Show full text]
  • Geochronology Database for Central Colorado
    Geochronology Database for Central Colorado Data Series 489 U.S. Department of the Interior U.S. Geological Survey Geochronology Database for Central Colorado By T.L. Klein, K.V. Evans, and E.H. DeWitt Data Series 489 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2010 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: T.L. Klein, K.V. Evans, and E.H. DeWitt, 2009, Geochronology database for central Colorado: U.S. Geological Survey Data Series 489, 13 p. iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1
    [Show full text]
  • Intrusive and Depositional Constraints on the Cretaceous Tectonic History of the Southern Blue Mountains, Eastern Oregon
    THEMED ISSUE: EarthScope IDOR project (Deformation and Magmatic Modification of a Steep Continental Margin, Western Idaho–Eastern Oregon) Intrusive and depositional constraints on the Cretaceous tectonic history of the southern Blue Mountains, eastern Oregon R.M. Gaschnig1,*, A.S. Macho2,*, A. Fayon3, M. Schmitz4, B.D. Ware4,*, J.D. Vervoort5, P. Kelso6, T.A. LaMaskin7, M.J. Kahn2, and B. Tikoff2 1SCHOOL OF EARTH AND ATMOSPHERIC SCIENCES, GEORGIA INSTITUTE OF TECHNOLOGY, 311 FERST DRIVE, ATLANTA, GEORGIA 30332, USA 2DEPARTMENT OF GEOSCIENCE, UNIVERSITY OF WISCONSIN-MADISON, 1215 W DAYTON STREET, MADISON, WISCONSIN 53706, USA 3DEPARTMENT OF EARTH SCIENCES, UNIVERSITY OF MINNESOTA TWIN CITIES, 310 PILLSBURY DRIVE SE, MINNEAPOLIS, MINNESOTA 55455, USA 4DEPARTMENT OF GEOSCIENCES, BOISE STATE UNIVERSITY, 1910 UNIVERSITY DRIVE, BOISE, IDAHO 83725, USA 5SCHOOL OF THE ENVIRONMENT, WASHINGTON STATE UNIVERSITY, PO BOX 64281, PULLMAN, WASHINGTON 99164, USA 6DEPARTMENT OF GEOLOGY AND PHYSICS, LAKE SUPERIOR STATE UNIVERSITY, CRAWFORD HALL OF SCIENCE, SAULT STE. MARIE, MICHIGAN 49783, USA 7DEPARTMENT OF GEOGRAPHY AND GEOLOGY, UNIVERSITY OF NORTH CAROLINA, DELOACH HALL, 601 SOUTH COLLEGE ROAD, WILMINGTON, NORTH CAROLINA 28403, USA ABSTRACT We present an integrated study of the postcollisional (post–Late Jurassic) history of the Blue Mountains province (Oregon and Idaho, USA) using constraints from Cretaceous igneous and sedimentary rocks. The Blue Mountains province consists of the Wallowa and Olds Ferry arcs, separated by forearc accretionary material of the Baker terrane. Four plutons (Lookout Mountain, Pedro Mountain, Amelia, Tureman Ranch) intrude along or near the Connor Creek fault, which separates the Izee and Baker terranes. High-precision U-Pb zircon ages indicate 129.4–123.8 Ma crystallization ages and exhibit a north-northeast–younging trend of the magmatism.
    [Show full text]
  • 71St Annual Meeting Society of Vertebrate Paleontology Paris Las Vegas Las Vegas, Nevada, USA November 2 – 5, 2011 SESSION CONCURRENT SESSION CONCURRENT
    ISSN 1937-2809 online Journal of Supplement to the November 2011 Vertebrate Paleontology Vertebrate Society of Vertebrate Paleontology Society of Vertebrate 71st Annual Meeting Paleontology Society of Vertebrate Las Vegas Paris Nevada, USA Las Vegas, November 2 – 5, 2011 Program and Abstracts Society of Vertebrate Paleontology 71st Annual Meeting Program and Abstracts COMMITTEE MEETING ROOM POSTER SESSION/ CONCURRENT CONCURRENT SESSION EXHIBITS SESSION COMMITTEE MEETING ROOMS AUCTION EVENT REGISTRATION, CONCURRENT MERCHANDISE SESSION LOUNGE, EDUCATION & OUTREACH SPEAKER READY COMMITTEE MEETING POSTER SESSION ROOM ROOM SOCIETY OF VERTEBRATE PALEONTOLOGY ABSTRACTS OF PAPERS SEVENTY-FIRST ANNUAL MEETING PARIS LAS VEGAS HOTEL LAS VEGAS, NV, USA NOVEMBER 2–5, 2011 HOST COMMITTEE Stephen Rowland, Co-Chair; Aubrey Bonde, Co-Chair; Joshua Bonde; David Elliott; Lee Hall; Jerry Harris; Andrew Milner; Eric Roberts EXECUTIVE COMMITTEE Philip Currie, President; Blaire Van Valkenburgh, Past President; Catherine Forster, Vice President; Christopher Bell, Secretary; Ted Vlamis, Treasurer; Julia Clarke, Member at Large; Kristina Curry Rogers, Member at Large; Lars Werdelin, Member at Large SYMPOSIUM CONVENORS Roger B.J. Benson, Richard J. Butler, Nadia B. Fröbisch, Hans C.E. Larsson, Mark A. Loewen, Philip D. Mannion, Jim I. Mead, Eric M. Roberts, Scott D. Sampson, Eric D. Scott, Kathleen Springer PROGRAM COMMITTEE Jonathan Bloch, Co-Chair; Anjali Goswami, Co-Chair; Jason Anderson; Paul Barrett; Brian Beatty; Kerin Claeson; Kristina Curry Rogers; Ted Daeschler; David Evans; David Fox; Nadia B. Fröbisch; Christian Kammerer; Johannes Müller; Emily Rayfield; William Sanders; Bruce Shockey; Mary Silcox; Michelle Stocker; Rebecca Terry November 2011—PROGRAM AND ABSTRACTS 1 Members and Friends of the Society of Vertebrate Paleontology, The Host Committee cordially welcomes you to the 71st Annual Meeting of the Society of Vertebrate Paleontology in Las Vegas.
    [Show full text]
  • 2021 Edelman Award Ceremony for Distinction in Practice
    2021 EDELMAN ogether, these awards demonstrate the power of advanced analytics at Intel, and its fundamental importance in our ability to deliver the technology AWARD Tleadership and reliable, top quality products the world needs and expects. CEREMONY — Kalani Ching, Intel Recognizing Distinction in the Practice of Analytics, Operations Research, and Management Science www.informs.org 2021 EDELMAN AWARD CEREMONY FOR DISTINCTION IN PRACTICE FRANZ EDELMAN AWARD Achievement in Advanced Analytics, Operations Research, & Management Science Emphasizing Beneficial Impact DANIEL H. WAGNER PRIZE Excellence in Operations Research Practice Emphasizing Innovative Methods and Clear Exposition UPS GEORGE D. SMITH PRIZE Strengthening Ties Between Academia & Industry Emphasizing Effective Academic Preparation INFORMS PRIZE Sustained Integration of Operations Research Emphasizing Long-Term, Multiproject Success The Edelman Award Ceremony 49 OCP 5 Ceremony Program 53 United Nations World Food Programme 6 Salute our Sponsors The Wagner Prize 7 Co-host—Dionne Aleman 57 Daniel H. Wagner Prize History 8 Co-host—Zahir Balaporia, CAP 58 2020 Wagner Prize Finalists Analytics and Operations Research Today 59 2020 Wagner Prize Winner 11 2021 Edelman Program Notes—Stephen Graves UPS George D. Smith Prize 14 Enriching the Lives of Every 63 UPS George D. Smith Prize History Person on Earth—Kalani Ching 65 2021 Smith Prize Competition 16 Operations Research: Billions and Billions of Benefits!—Jeffrey M. Alden 65 Smith Prize Past Winners TABLE OF Franz Edelman Award INFORMS Prize 19 Recognizing and Rewarding Real 71 INFORMS Prize History Achievement in O.R. and Analytics 71 INFORMS Prize Winners 20 The Finest Step Forward: Journey CONTENTS to the Franz Edelman Award 72 INFORMS Prize Criteria 23 Edelman First-Place Award Recipients 73 2021 INFORMS Prize Winner 26 The 2021 Selection Committee & Verifiers INFORMS 27 The 2021 Coaches & Judges 75 About INFORMS 29 The Edelman Laureates 76 Advancing the Practice of O.R.
    [Show full text]
  • 1 TIMESCALE for CLIMATIC EVENTS of SUBBOREAL/SUBATLANTIC TRANSITION RECORDED at the VALAKUPIAI SITE, LITHUANIA Jacek Pawlyta1,2
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by BSU Digital Library RADIOCARBON, Vol 49, Nr 2, 2007, p 1–9 © 2007 by the Arizona Board of Regents on behalf of the University of Arizona TIMESCALE FOR CLIMATIC EVENTS OF SUBBOREAL/SUBATLANTIC TRANSITION RECORDED AT THE VALAKUPIAI SITE, LITHUANIA Jacek Pawlyta1,2 • Algirdas Gaigalas3 • Adam MichczyÒski1 • Anna Pazdur1 • Aleksander Sanko4 ABSTRACT. Oxbow lake deposits of the Neris River at the Valakupiai site in Vilnius (Lithuania) have been studied by dif- ferent methods including radiocarbon dating. A timescale was attained for the development of the oxbow lake and climatic events recorded in the sediments. 14C dates obtained for 24 samples cover the range 990–6500 BP (AD 580 to 5600 BC). Medieval human activity was found in the upper part of the sediments. Mollusk fauna found in the basal part of the terrace indicate contact between people living in the Baltic and the Black Sea basins. Mean rates were calculated for erosion of the river and for accumulation during the formation of the first terrace. INTRODUCTION This work presents the results of radiocarbon dating of samples collected at the Valakupiai site, near Vilnius in eastern Lithuania (54°43′58″N, 25°18′33″E; 98.5 m asl) (Figure 1). Special attention was paid to the remnant oxbow lake in the Neris River valley and to the lake-bog deposits filling it. Detailed study of the deposits delivered specific information that enabled paleoecological recon- struction of the site, as well as a description of the geochronological evolution of the oxbow lake and accompanying climatic events.
    [Show full text]
  • 183.Full.Pdf
    DANIEL I. AXELROD Dept. Geology, University of California, Los Angeles, Calif. Post-Pliocene Uplift of the Sierra Nevada, California Abstract: Reconstructed stream profiles and paleo- The postulate of a high Tertiary barrier, and of botanical evidence suggest that in the Yosemite only 4000 (Yosemite sector) to 2000 feet (Lake region altitude increased approximately 4000 feet Tahoe sector) uplift in the Pleistocene raises prob- following the Broad Valley stage. Since this was lems: the Tertiary section has defied erosion; fine- preceded by a 2500- to 3000-foot uplift of the Late grained sediments were deposited well up in the Pliocene Boreal ("Eocene") surface during the range and at its summit; formations were deposited Plio-Pleistocene transition, total post-Pliocene up- across the crest; Tertiary rivers and basalt flowed lift is about 6500-7000 feet. across the summit; faulting and warping of dated With similar methods, divergent results have sections and erosion surfaces show post-Pliocene been reported for the Lake Tahoe sector. The uplift of 4000-9000 feet; and the scarps have re- presence in the summit region of Miocene de- sisted erosion. These "problems" disappear if the ciduous hardwood forests typical of mild-tem- range originated as a major post-Pliocene topo- perate climate, the absence there of montane graphic barrier. conifers, the spatial relations of the Miocene forest Two basic weaknesses to the method of de- zones, and the regional pattern of climate they sug- termining Tertiary altitude from ancient stream gest all imply altitudes near 2000 feet. Recon- profiles are: (1) The assumption that certain well- structed stream profiles indicate an altitude of graded stretches of the ancient streams had pretilt 5000-7000 feet.
    [Show full text]
  • Overkill, Glacial History, and the Extinction of North America's Ice Age Megafauna
    PERSPECTIVE Overkill, glacial history, and the extinction of North America’s Ice Age megafauna PERSPECTIVE David J. Meltzera,1 Edited by Richard G. Klein, Stanford University, Stanford, CA, and approved September 23, 2020 (received for review July 21, 2020) The end of the Pleistocene in North America saw the extinction of 38 genera of mostly large mammals. As their disappearance seemingly coincided with the arrival of people in the Americas, their extinction is often attributed to human overkill, notwithstanding a dearth of archaeological evidence of human predation. Moreover, this period saw the extinction of other species, along with significant changes in many surviving taxa, suggesting a broader cause, notably, the ecological upheaval that occurred as Earth shifted from a glacial to an interglacial climate. But, overkill advocates ask, if extinctions were due to climate changes, why did these large mammals survive previous glacial−interglacial transitions, only to vanish at the one when human hunters were present? This question rests on two assumptions: that pre- vious glacial−interglacial transitions were similar to the end of the Pleistocene, and that the large mammal genera survived unchanged over multiple such cycles. Neither is demonstrably correct. Resolving the cause of large mammal extinctions requires greater knowledge of individual species’ histories and their adaptive tolerances, a fuller understanding of how past climatic and ecological changes impacted those animals and their biotic communities, and what changes occurred at the Pleistocene−Holocene boundary that might have led to those genera going extinct at that time. Then we will be able to ascertain whether the sole ecologically significant difference between previous glacial−interglacial transitions and the very last one was a human presence.
    [Show full text]
  • High-Resolution U-Pb Geochronology of Terrestrial Cretaceous-Paleogene and Permo-Triassic Boundary Sequences in North America
    High-resolution U-Pb Geochronology of Terrestrial Cretaceous-Paleogene and Permo-Triassic Boundary Sequences in North America by William Stuart Mitchell, III A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Chemistry in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Paul Renne, Co-chair Professor Evan Williams, Co-chair Professor Heino Nitsche Professor Donald DePaolo Spring 2014 High-resolution U-Pb Geochronology of Terrestrial Cretaceous-Paleogene and Permo-Triassic Boundary Sequences in North America Copyright 2014 by William Stuart Mitchell, III 1 Abstract High-resolution U-Pb Geochronology of Terrestrial Cretaceous-Paleogene and Permo-Triassic Boundary Sequences in North America by William Stuart Mitchell, III Doctor of Philosophy in Chemistry University of California, Berkeley Professor Paul Renne, Co-chair Professor Evan Williams, Co-chair High-resolution geochronology provides a means to evaluate the timescales of responses to major shifts in Earth history, such as ecosystem recovery following a major impact event or a mass extinction. Additionally, geochronology can be used to correlate sections across the marine and terrestrial realm and around the world. Changes in ecosystems or isotopic composition of deposited rocks will be influenced by local effects, but can also have a global signal. With geochronlogy, the same time interval can be found in distant regions, and if a phenomenon (e.g. a carbon isotope excursion) was global in scope, many different localities each from the same time interval would show the same signal. Here I present high-resolution uranium-lead geochronology pertaining to two mass ex- tinctions: the Cretaceous-Paleogene mass extinction (around 66 million years ago, Ma) and the Permo-Triassic mass extinction (around 252 Ma).
    [Show full text]
  • Trackflow, a New Versatile Microscope System for Fission Track
    https://doi.org/10.5194/gchron-2019-13 Preprint. Discussion started: 23 October 2019 c Author(s) 2019. CC BY 4.0 License. Technical note: TRACKFlow, a new versatile microscope system for fission track analysis Gerben Van Ranst1, Philippe Baert2, Ana Clara Fernandes2, Johan De Grave1 1Department of Geology, Ghent University, Ghent, 9000, Belgium 5 2Nikon Belux, Groot-Bijgaarden, 1702, Belgium Correspondence to: Gerben Van Ranst ([email protected]) Abstract. We here present TRACKFlow, a new system with dedicated modules for the fission track (FT) laboratory. It is based on the motorised Nikon Eclipse Ni-E upright microscope with the Nikon DS-Ri2 full frame camera and is embedded within the Nikon 10 NIS-Elements Advanced Research software package. TRACKFlow decouples image acquisition from analysis to decrease schedule stress of the microscope. The system further has the aim of being versatile, adaptable to multiple preparation protocols and analysis approaches. It is both suited for small-scale laboratories and is also ready for upscaling to high-throughput imaging. The versatility of the system, based on the operators’ full access to the NIS-Elements package, exceeds that of other systems for FT and further expands to stepping away from the dedicated FT microscope towards a general microscope for 15 Earth Sciences, including dedicated modules for FT research. TRACKFlow consists of a number of user-friendly protocols which are based on the well plate design that allows sequential scanning of multiple samples without the need of replacing the slide on the stage. All protocols include a sub-protocol to scan a map of the mount for easy navigation through the samples on the stage.
    [Show full text]