Module-4 Excavation and Dating Techniques Topic
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Absolute Time Radiometric Dating: the Source of the Dates on the Geologic Time Scale
Absolute Time Radiometric Dating: the source of the dates on the Geologic Time Scale Radiometric Dating • Actually a simple technique. • Only two measurements are needed: • 1. The parent:daughter ratio measured with a mass spectrometer. • 2. The decay constant measured by a scintillometer. Basis of the Technique • Radioactive elements “decay.” Decay occurs as an element changes to another element, e.g. uranium to lead. • The parent element is radioactive, the daughter element is stable. • The decay rate is constant. What is Radioactivity? • Radioactivity occurs when certain elements literally fall apart. • Usually protons and neutrons are emitted by the nucleus. • Sometimes an electron is emitted by the nucleus, which changes a neutron to a proton. • Sometimes an electron is captured. What causes radioactivity? • Carbon-14 is produced by cosmic ray bombardment of Nitrogen-14 in the atmosphere. • All other radioactive elements were produced by supernova explosions before our solar system formed. This is called explosive nucleosynthesis. Common Radioactive Elements, Parents and Daughters • Carbon-14, C14 Nitrogen-14, N14 • Uranium-235, U235 Lead-207, Pb207 • Potassium-40, K40 Argon-40, Ar40 • Uranium-238, U238 Lead-206, Pb206 • Rubidium-87, Rb87 Strontium-87, Sr87 Basis of the Technique • As the parent element decays, its amount decreases while the amount of the daughter element increases. This gives us a ratio of parent:daughter elements. • The decay rate is geometric rather than linear. Unaffected by heat or pressure. Key Term • Half-Life: the amount of time for half the atoms of a radioactive element to decay. Doesn’t matter how many atoms started, half will decay. -
Recent Achievements in Archaeomagnetic Dating in the Iberian Peninsula: Application to Roman and Mediaeval Spanish Structures
Journal of Archaeological Science 35 (2008) 1389e1398 http://www.elsevier.com/locate/jas Recent achievements in archaeomagnetic dating in the Iberian Peninsula: application to Roman and Mediaeval Spanish structures M. Go´mez-Paccard a,*, E. Beamud b a Research Group of Geodynamics and Basin Analysis, Department of Stratigraphy, Paleontology and Marine Geosciences, Universitat de Barcelona, Campus de Pedralbes, E-08028 Barcelona, Spain b Research Group of Geodynamics and Basin Analysis, Paleomagnetic Laboratory (UB-CSIC), Institute of Earth Sciences ‘‘Jaume Almera’’, Sole´ i Sabarı´s, E-08028 Barcelona, Spain Received 18 May 2007; received in revised form 25 September 2007; accepted 8 October 2007 Abstract Archaeomagnetic studies in Spain have undergone a significant progress during the last few years and a reference curve of the directional variation of the geomagnetic field over the past two millennia is now available for the Iberian Peninsula. These recent developments have made archaeomagnetism a straightforward dating tool for Spain and Portugal. The aim of this work is to illustrate how this secular variation curve can be used to date the last use of several burnt structures from Spain. Four combustion structures from three archaeological sites with ages ranging from Roman to Mediaeval times have been studied and archaeomagnetically dated. The directions of the characteristic remanent magnetization of each structure have been obtained from classical thermal and alternating field (AF) demagnetization procedures, and a mean direction for each combustion structure has been obtained. These directional results have been compared with the new reference curve for Iberia, providing archae- omagnetic dates for the last use of the kilns. -
Archaeological Tree-Ring Dating at the Millennium
P1: IAS Journal of Archaeological Research [jar] pp469-jare-369967 June 17, 2002 12:45 Style file version June 4th, 2002 Journal of Archaeological Research, Vol. 10, No. 3, September 2002 (C 2002) Archaeological Tree-Ring Dating at the Millennium Stephen E. Nash1 Tree-ring analysis provides chronological, environmental, and behavioral data to a wide variety of disciplines related to archaeology including architectural analysis, climatology, ecology, history, hydrology, resource economics, volcanology, and others. The pace of worldwide archaeological tree-ring research has accelerated in the last two decades, and significant contributions have recently been made in archaeological chronology and chronometry, paleoenvironmental reconstruction, and the study of human behavior in both the Old and New Worlds. This paper reviews a sample of recent contributions to tree-ring method, theory, and data, and makes some suggestions for future lines of research. KEY WORDS: dendrochronology; dendroclimatology; crossdating; tree-ring dating. INTRODUCTION Archaeology is a multidisciplinary social science that routinely adopts an- alytical techniques from disparate fields of inquiry to answer questions about human behavior and material culture in the prehistoric, historic, and recent past. Dendrochronology, literally “the study of tree time,” is a multidisciplinary sci- ence that provides chronological and environmental data to an astonishing vari- ety of archaeologically relevant fields of inquiry, including architectural analysis, biology, climatology, economics, -
Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents
Consultation Draft Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents Foreword............................................................................................................................. 3 PART 1 - OVERVIEW .............................................................................................................. 3 1. Introduction .............................................................................................................. 3 The Quaternary stratigraphical framework ........................................................................ 4 Palaeogeography ........................................................................................................... 6 Fitting the archaeological record into this dynamic landscape .............................................. 6 Shorter-timescale division of the Late Pleistocene .............................................................. 7 2. Scientific Dating methods for the Pleistocene ................................................................. 8 Radiometric methods ..................................................................................................... 8 Trapped Charge Methods................................................................................................ 9 Other scientific dating methods ......................................................................................10 Relative dating methods ................................................................................................10 -
The Physical Evolution of the North Avon Levels a Review and Summary of the Archaeological Implications
The Physical Evolution of the North Avon Levels a Review and Summary of the Archaeological Implications By Michael J. Allen and Robert G. Scaife The Physical Evolution of the North Avon Levels: a Review and Summary of the Archaeological Implications by Michael J. Allen and Robert G. Scaife with contributions from J.R.L. Allen, Nigel G. Cameron, Alan J. Clapham, Rowena Gale, and Mark Robinson with an introduction by Julie Gardiner Wessex Archaeology Internet Reports Published 2010 by Wessex Archaeology Ltd Portway House, Old Sarum Park, Salisbury, SP4 6EB http://www.wessexarch.co.uk/ Copyright © Wessex Archaeology Ltd 2010 all rights reserved Wessex Archaeology Limited is a Registered Charity No. 287786 Contents List of Figures List of Plates List of Tables Editor’s Introduction, by Julie Gardiner .......................................................................................... 1 INTRODUCTION The Severn Levels ............................................................................................................................ 5 The Wentlooge Formation ............................................................................................................... 5 The Avon Levels .............................................................................................................................. 6 Background ...................................................................................................................................... 7 THE INVESTIGATIONS The research/fieldwork: methods of investigation .......................................................................... -
Ervan Garrison Second Edition
Natural Science in Archaeology Ervan Garrison Techniques in Archaeological Geology Second Edition Natural Science in Archaeology Series editors Gu¨nther A. Wagner Christopher E. Miller Holger Schutkowski More information about this series at http://www.springer.com/series/3703 Ervan Garrison Techniques in Archaeological Geology Second Edition Ervan Garrison Department of Geology, University of Georgia Athens, Georgia, USA ISSN 1613-9712 Natural Science in Archaeology ISBN 978-3-319-30230-0 ISBN 978-3-319-30232-4 (eBook) DOI 10.1007/978-3-319-30232-4 Library of Congress Control Number: 2016933149 # Springer-Verlag Berlin Heidelberg 2016 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. -
Scientific Dating in Archaeology
SCIENTIFIC DATING IN ARCHAEOLOGY Tsuneto Nagatomo 1. AGE DETERMINATION IN ARCHAEOLOGY • Relative Age: stratigraphy, typology • Absolute Chronology: historical data • Age Determination by (natural) Scientific Methods: Numerical age (or chronometric age) Relative age 2. AGE DETERMINATION BY SCIENTIFIC METHODS 2-1. Numerical Methods • Radiometric Dating Methods Radioactive Isotope: radiocarbon, potassium-argon, argon-argon, uranium series Radiation Damage: fission track, luminescence, electron spin resonance • Non-Radiometric Dating Methods Chemical Change: amino acid, obsidian hydration 2-2. Relative Methods • Archaeomagnetism & palaeomagnetism, dendrochronology, fluorite 3. RADIOMETRIC METHODS 3-1. Radioactive Isotopes The dating clock is directly provided by radioactive decay: e.g. radiocarbon, potassium-argon, and the uranium-series. The number of a nuclide (Nt) at a certain time (t) decreases by decaying into its daughter nuclide. The number of a nuclide (dN) that decays within a short time (dt) is proportional to the total number of the nuclide at time (t) (Nt): d Nt /dt = -λNt (1) where λ: decay constant. Then, Nt is derived from (1) as Nt = N0 exp(-0.693t/T1/2) (2) …Where N0 is the number of the isotope at t = 0 and T1/2 is its half-life. Thus, the equation from this is: t = (T1/2/0.693)exp(N0/Nt) When the values of T1/2 and N0 are known, we get t by evaluating the value Nt. The radiocarbon technique is the typical one in which the decrease of the parent nuclide is the measure of dating. On the other hand, the decrease of the parent nuclide and increase of the daughter nuclide, or their ratio, is the measure of dating in potassium-argon and the uranium-series. -
Dating Techniques.Pdf
Dating Techniques Dating techniques in the Quaternary time range fall into three broad categories: • Methods that provide age estimates. • Methods that establish age-equivalence. • Relative age methods. 1 Dating Techniques Age Estimates: Radiometric dating techniques Are methods based in the radioactive properties of certain unstable chemical elements, from which atomic particles are emitted in order to achieve a more stable atomic form. 2 Dating Techniques Age Estimates: Radiometric dating techniques Application of the principle of radioactivity to geological dating requires that certain fundamental conditions be met. If an event is associated with the incorporation of a radioactive nuclide, then providing: (a) that none of the daughter nuclides are present in the initial stages and, (b) that none of the daughter nuclides are added to or lost from the materials to be dated, then the estimates of the age of that event can be obtained if the ration between parent and daughter nuclides can be established, and if the decay rate is known. 3 Dating Techniques Age Estimates: Radiometric dating techniques - Uranium-series dating 238Uranium, 235Uranium and 232Thorium all decay to stable lead isotopes through complex decay series of intermediate nuclides with widely differing half- lives. 4 Dating Techniques Age Estimates: Radiometric dating techniques - Uranium-series dating • Bone • Speleothems • Lacustrine deposits • Peat • Coral 5 Dating Techniques Age Estimates: Radiometric dating techniques - Thermoluminescence (TL) Electrons can be freed by heating and emit a characteristic emission of light which is proportional to the number of electrons trapped within the crystal lattice. Termed thermoluminescence. 6 Dating Techniques Age Estimates: Radiometric dating techniques - Thermoluminescence (TL) Applications: • archeological sample, especially pottery. -
Isotope Geochemistry I Lectures & Exercises
Tools and methods Geochronology Methods relying on the decay of naturally occurring radiogenic isotopes: Parent isotope Daughter isotope 1. Potassium-40 -> Argon-40 2. Rubidium-87 -> Strontium-87 3. Uranium-235 -> Lead-207 4. Uranium-238 -> Lead-206 5. Thorium-232 -> Lead-208 Radioactivity Natural and artificial radioactivity Natural radioactivity Isotopes that have been here since the earth formed: 238U, 235U, 232Th, 40K Isotopes produced by cosmic rays from the sun, i.e cosmogenic radionuclides: 14C, 10Be, 36Cl Synthetic radioisotopes Made in nuclear reactors when atoms are split (fission). Produced usinc cyclotrons, linear accererators... 39 39 K (n, p) Ar 19 18 The dawn of radiometric dating “U-Pb” method • Boltwood studied radioactive elements and found that Pb was always present in uranium and thorium ores. Pb must be the final product of the radioactive decay. • In 1907, he reasoned that since he knew the rate at which uranium breaks down (its half-life), he could use the proportion of lead in the uranium ores (chemical dating, isotopes not discovered yet) as a meter or clock. • His observations and calculations put Earth's age at 2.2 billion years. He accumulation method • Based on the fact that 235U, 238U and 232Th emit 7, 8 and 6 α-particles, resp. in their decay to Pb • U and Th concentration can be determined chemically and the current rate of He production can be calculated • The sample is heated to release He and the helium-retention age is calculated Radioactive decay half-lifes, T1/2 • if it is possible to determine the -
Datin History of Rock Chronometric/Radiometric G
Ed Planansky, Hay Springs, NE © 2008 DATIN HISTORY OF ROCK CHRONOMETRIC/RADIOMETRIC G Educational Objective: To help students become aware of dating techniques used to date very ancient (millions of years) to relatively recent (tens of thousands of years) events in geologic time. Target Audience: Any science or math class with adaptations for age groups and class setting. Questions To Be Answered: 1. What is the half-life of a radioactive isotope? 2. How can the half life of an isotope be used to date anything? 3. Which isotope dating method is most likely to give the most accurate dating of a sediment or specimen? 4. Given a hypothetical amount of material present in a sample compared to the amount that was present at formation be able to date events or sediments. HALF-LIFE Following World War I and the invention of a device called a mass spectrometer more than 200 isotopes of the 92 naturally occurring elements were found. Isotopes are atoms of elements that have the same atomic number but different atomic masses, they are the same element but have different weights because of different numbers of neutrons in the nucleus of the atom. Because the isotopes are essentially the same element they have the same chemical properties but have different physical properties. For the purposes of dating geologic times the property we are concerned with is radioactive decay. Each radioactive isotope decays, by emitting alpha or beta particles and becoming a new element many of which are stable and no longer decay. The time it takes for half of a sample to decay into new material(s) is called its half-life. -
Dating and Chronology Building - R
ARCHAEOLOGY – Dating and Chronology Building - R. E. Taylor DATING AND CHRONOLOGY BUILDING R. E. Taylor University of California, USA Keywords: Dating methods, chronometric dating, seriation, stratigraphy, geochronology, radiocarbon dating, potassium-argon/argon-argon dating, Pleistocene, Quaternary. Contents 1. Chronological Frameworks 1.1 Relative and Chronometric Time 1.2 History and Prehistory 2. Chronology in Archaeology 2.1 Historical Development 2.2 Geochronological Units 3. Chronology Building 3.1 Development of Historic Chronologies 3.2 Development of Prehistoric Chronologies 3.3 Stratigraphy 3.4 Seriation 4. Chronometric Dating Methods 4.1 Radiocarbon 4.2 Potassium-argon and Argon-argon Dating 4.3 Dendrochronology 4.4 Archaeomagnetic Dating 4.5 Obsidian Hydration Acknowledgments Glossary Bibliography Biographical Sketch Summary One of the purposes of archaeological research is the examination of the evolution of human cultures.UNESCO Since a fundamental defini– tionEOLSS of evolution is “change over time,” chronology is a fundamental archaeological parameter. Archaeology shares with a number of otherSAMPLE sciences concerned with temporally CHAPTERS mediated phenomenon the need to view its data within an accurate chronological framework. For archaeology, such a requirement needs to be met if any meaningful understanding of evolutionary processes is to be inferred from the physical residue of past human behavior. 1. Chronological Frameworks Chronology orders the sequential relationship of physical events by associating these events with some type of time scale. Depending on the phenomenon for which temporal placement is required, it is helpful to distinguish different types of time scales. ©Encyclopedia of Life Support Systems (EOLSS) ARCHAEOLOGY – Dating and Chronology Building - R. E. Taylor Geochronological (geological) time scales temporally relates physical structures of the Earth’s solid surface and buried features, documenting the 4.5–5.0 billion year history of the planet. -
V Semester Zoology Fossils and Fossil Dating
V SEMESTER ZOOLOGY FOSSILS AND FOSSIL DATING Fossils can include anything that gives an indication of the existence of prehistoric organisms. The Latin word Fossilium means ‘dug out’, which in earlier times meant to include any traces of body of animals and plants buried and preserved by natural causes. George Curvier (1769-1832) is considered ‘Father of palaeontology’, who studied fossils scientifically to develop phylogenies. Types of fossils Based on the mode of formation of fossils, they can be categorised in several types. Fossilisation is a rare phenomenon, which takes place under specialised conditions. The study of natural process of death, burial, decomposition, preservation and transformation into fossil is called taphonomy. Fossils are the only direct evidence of the biological events in the history of earth and hence important in the understanding and construction of the evolutionary history of different groups of animals and plants. 1. Petrifaction Petrifaction is molecule-by-molecule replacement of organic matter by inorganic compounds, viz. silica, calcium carbonate or iron pyrites. It literally means “turned into stone” and takes place in buried situations, particularly at the bottom of lakes, ponds or sea, where there are sediments rich in calcium carbonate and silica. Over millions of years, inorganic matter replaces the entire bony material, making an exact replica of the original. By this time sediments transform into sedimentary rocks, in which fossils can remain preserved for a long time. Most of the old fossils are petrified, e.g. shells of molluscs, arthropods and fish skeletons. 2. Preservation of footprints When animals walk on wet soil and sand, they leave trail of footprints or limbless animals and worms may leave tracks and trails in mud.