The Importance of Radiocarbon Dating To Archaeology

- Kelly Long, Associate State Archaeologist

Several timescale problems arise when it comes to dating archaeological samples. For example, Christian time counts the birth of Christ as the beginning, AD 1 (Anno Domini); everything that occurred before Christ is counted backwards from AD as BC (Before Christ). The Greeks consider the first Olympic Games as the beginning or 776 BC. The Muslims count the Prophet’s departure from Mecca, or the Hegira, as their beginning at AD 662. The Mayan calendar used 3114 BC as their reference. More recently is the radiocarbon date of 1950 AD or before present, BP.

There are two techniques for dating in archaeological sites: relative and absolute dating.

Relative dating stems from the idea that something is younger or older relative to something else. In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground. Although relative dating can work well in certain areas, several problems arise. Rodents, for example, can create havoc in a site by moving items from one context to another. Natural disasters like floods can sweep away top layers of sites to other locations. Absolute dating represents the absolute age of the sample before the present. Historical documents and calendars can be used to find such absolute dates; however, when working in a site without such documents, it is hard for absolute dates to be determined.

As long as there is organic material present, radiocarbon dating is a universal dating technique that can be applied anywhere in the world. It is good for dating for the last 50,000 years to about 400 years ago and can create chronologies for areas that previously lacked calendars. In 1949, American chemist Willard Libby, who worked on the development of the atomic bomb, published the first set of radiocarbon dates. His radiocarbon dating technique is the most important development in absolute dating in archaeology and remains the main tool for dating the past 50,000 years.



How It Works:

Carbon has 3 isotopic forms: Carbon-12, Carbon-13, and Carbon-14. The numbers refer to the atomic weight, so Carbon-12 has 6 protons and 6 neutrons, Carbon-13 has 6 protons and 7 neutrons, and Carbon-14 has 6 protons and 8 neutrons. The extra neutrons in Carbon-14’s case make it radioactive (thus the term, radiocarbon).

Radiocarbon is produced in the upper atmosphere after Nitrogen-14 isotopes have been impacted by cosmic radiation. Radiocarbon is then taken in by plants through photosynthesis, and these plants in turn are consumed by all the organisms on the planet.

So every living thing has a certain amount of radiocarbon within them. After an organism dies, the radiocarbon decreases through a regular pattern of decay. This is called the half-life of the isotope. The time taken for half of the atoms of a radioactive isotope to decay in Carbon-14’s case is about 5730 years.

Half-lives vary according to the isotope, for example, Uranium-238 has a half-life of 4500 million years where as Nitrogen-17 has a half-life of 4.173 seconds! Looking at the graph, 100% of radiocarbon in a sample will be reduced to 50% after 5730 years. In 11,460 years, half of the 50% will remain, or 25%, and so on.



Limitations and calibration:

When Libby was first determining radiocarbon dates, he found that before 1000 BC his dates were earlier than calendar dates. He had assumed that amounts of Carbon-14 in the atmosphere had remained constant through time. In fact, levels of Carbon-14 have varied in the atmosphere through time. One good example would be the elevated levels of Carbon-14 in our atmosphere since WWII as a result of atomic bombs testing. Therefore, radiocarbon dates need to be calibrated with other dating techniques to ensure accuracy.

Plants are not the only organism that can process Carbon-14 from the air. Plankton absorbs, Carbon-14 from the ocean much like terrestrial plants absorb Carbon-14 from the air. Since plankton is the foundation of the marine food chain, Carbon-14 is spread throughout aquatic life. Shellfish remains are common in coastal and estuarine archaeological sites, but dating these samples require a correction for the “reservoir effect” a process whereby "old carbon" is recycled and incorporated into marine life especially shellfish inflating their actual age in some cases several centuries. In recognition of this problem archaeologists have developed regional reservoir correction rates based on ocean bottom topography, water temperature, coastline shape and paired samples of terrestrial and marine objects found together in an archaeological feature such as a hearth.

Long tree-ring sequences have been developed throughout the world and can be used to check and calibrate radiocarbon dates. An extensive tree-ring sequence from the present to 6700 BC was developed in Arizona using California bristlecone pine (Pinus aristata), some of which are 4900 years old, making them the oldest living things on earth. Additional sequences have been developed for oak species in Ireland and Germany, ice core samples, and coral reefs from Caribbean islands. These sequences have helped to calibrate radiocarbon dates to calendar years, thus making them more accurate. Normally after 12,500 BP, the coral dating is used.

Example of calibration: 3700 ± 100 BP (P - 685). The first number corresponds to the years before present. The second number is the standard deviation or error for the date. It creates a date range of 3600 - 3800 years before present that the sample can fall under. The letter in parenthesis is the lab the sample was shipped to, in this case Philadelphia, followed by the lab analysis number.

Bibliography:

Greene, Kevin
1983 Archaeology: An Introduction, 3rd edition, Philadelphia: University of Pennsylvania Press. Pp. 114-123.

Refew, Colin, and Paul Bahn
1996 Archaeology: Theories, Methods, and Practice, 2nd edition. London: Thames and Hudson. Pp. 111-162.

Thomas, David Hurst
1998 Archaeology, 3rd edition. Fort Worth: Harcourt Brace College Publishers. Pp. 186-194.
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Dating the Past

1. BACKGROUND

It is difficult for prehistorians working in the twenty-first century to conceptualise the problems experienced by their predecessors, and approaches to interpretation before the 1960s are consistently criticised. Culture history and diffusionism may - with hindsight - seem excessively preoccupied with classification and social evolution, and to have applied unsophisticated historical interpretations instead of asking fundamental questions about human behaviour.

2. TYPOLOGY AND CROSS-DATING

It must be made clear at the outset that typology is not, strictly speaking, a dating method, but a means of placing artefacts into some kind of order. Classification divides things up for the purposes of description, whereas typology seeks to identify and analyse changes that will allow artefacts to be placed into sequences.

* TYPOLOGY IN TEXAS ARCHEOLOGY 'The type is the basic unit of classification in archeology. In order to establish order and to facilitate analysis, the archeologist divides his data into typological categories.' (Ellen Sue Turner and Thomas R. Hester: Texas State Historical Association

* LITHICS-Net Point Type Information: Projectile Point Data Indexed By Morphology (Shape). Guide for the identification of North American stone tools (Art Gumbus)

* Stronsay flints: 'The discovery of two tiny flint arrowheads in Stronsay could represent the earliest evidence of human activity found in Orkney – if not Scotland - to date. ... Flint experts Caroline Wickham-Jones and Torbin Ballin subsequently identified them as very early forms of prehistoric arrowheads – a type derived from a classification known as Ahrensburgian, found across the plains of north western Europe.' (Orkneyjar)

2.1. Sequence dating and seriation

These techniques both place assemblages of artefacts into relative order. Petrie used sequence dating to work back from the earliest historical phases of Egypt into pre-dynastic Neolithic times, using groups of contemporary artefacts deposited together at a single time in graves. Seriation was developed in the USA to place in order finds from strata or other kinds of assemblages such as potsherds collected from the surface of sites.

* William Matthew Flinders Petrie (1853-1942) 'He developed a method for establishing the historical chronology of a site based on identifying different styles of pottery. Petrie was known and respected for his belief in the importance of evidence like pot sherds for informing the archaeologist about life in the past.' (Petrie Museum, University College London)

* AN EXERCISE IN SERIATION DATING (PDF file) 'This method of assigning dates to sites ... is based on the fact that a cultural trait, like the type of jeans worn by teens, experiences popularity peaks, in other words, an artifact's popularity rises to a high point and then trails off, sometimes even to extinction.' (George Brauer)

* SERIATION APPLET 'The purpose of this Java program is to allow you to try your hand at determining the proper chronological order the sites should be in according to their seriation.' (MSU EMuseum)

3. HISTORICAL DATING

Prehistorians sometimes overestimate the accuracy and detail of frameworks based on historical evidence; in practice, early written sources may provide little more information than a scatter of radiocarbon dates. The extent of documentation varied considerably in 'historical' cultures and the information that survives is determined by a variety of factors.

* CAVSENNAE / CAVSENNIS Romano-British Town A range of inscriptions and documentary sources brought to bear on dating a small town at Ancaster in Lincolnshire; minor settlements of this kind rarely if ever featured in historical documents (WWW.Roman-Britain.ORG)

* The Thera (Santorini) Volcanic Eruption and the Absolute Chronology of the Aegean Bronze Age A PDF file about Sturt W. Manning's book A test of time: the volcano of Thera and the chronology and history of the Aegean and east Mediterranean in the mid second millennium BC (Oxford: Oxbow Books, 1999), which focuses on the difficulty of reconciling scientific and historical dates.

3.1. Applying historical dates to sites

If a context containing burnt debris and broken artefacts is excavated on a site from a historical period, it is tempting to search the local historical framework for references to warfare or a disaster in the region, and to date the excavated context accordingly.

* In Vesuvius' Shadow New excavation at the most famous ancient site and dated by a historically attested destruction in AD 79: 'Although the Anglo-American Project is interested in the conditions of city life in A.D. 79, the year Vesuvius erupted, we are investigating below the destruction level to understand the whole history of activity and development in VI,1--from its fourth-century B.C. huts to its burial in the late first century A.D.' (Archaeology Magazine).

* Head Street Excavations Excavation in Colchester, England, where traces of destruction dated by the Roman historian Tacitus have been revealed: 'Whenever a Roman house is discovered in Colchester dating to the AD 50s, it almost invariably turns out to have been destroyed by fire. And so it proved at Head Street, where the latest excavation revealed yet another Roman house which was destroyed during the Boudican revolt. The pattern is so consistent that it seems that when Boudica and her followers put the Roman town to the torch during the famous British revolt of AD 60 or 61, the destruction must have been total - every building was burnt.' (Colchester Archaeological Trust).

4.4. SCIENTIFIC DATING TECHNIQUES

The transformation of archaeological dating that began around 1950 continues, but archaeologists may overlook the revolution in scientific dating that had already taken place in geology during the first half of the twentieth century; from this wider perspective, the emergence of radiocarbon dating may seem slightly less dramatic

* Dating rock art Superb introduction to traditional and scientific dating methods and their application. 'The major methodological limitation in rock art studies is that art assemblages can be difficult to date. However, chronological data is crucial to many types of analysis in which rock art evidence is integrated with other archaeological and environmental information. This section will briefly survey the range of dating techniques used in contemporary rock art studies. These fall into two broad categories:

a) Relative dating methods such as degree of weathering, superimposition analysis, stylistic analysis and inter-site patterning.

b) Absolute dating methods such as analysis on the basis of subjects depicted, consistent association with datable deposits, the dating of stratified deposits associated with rock art and the direct dating of the art itself.' ( School of Human and Environmental Sciences, University of New England, Australia)

* Archaeometry and Stonehenge An example of the application of modern scientific dating to a major prehistoric site (English Heritage)

* Research Laboratory for Archaeology and the History of Art 'The department is dedicated to the development and application of scientific methods to the study of the past.' Lots of informative links (Oxford University)

4.1. Geological time-scales

Accurate knowledge of the age of the Earth was of little direct help to archaeologists, but it emphasised the potential of scientific dating techniques. The first half of the twentieth century witnessed similar progress that began with the dating of recent geological periods in which early hominids lived, and ended with the introduction of radiocarbon dating.

* Tour of geologic time 'Here you can journey through the history of the Earth, with stops at particular points in time to examine the fossil record and stratigraphy.' (University of California Museum of Paleontology)

* RADIOMETRIC TIME SCALE 'The discovery of the natural radioactive decay of uranium in 1896 by Henry Becquerel, the French physicist, opened new vistas in science. In 1905, the British physicist Lord Rutherford--after defining the structure of the atom-- made the first clear suggestion for using radioactivity as a tool for measuring geologic time directly...' (U.S. Geological Survey)

4.2. Climatostratigraphy

While some geologists concentrated on the age of the Earth, others studied distinctive surface traces left behind by changes in the extent of polar ice during the most recent (Quaternary) geological period. They identified a succession of Ice Ages alternating with temperate conditions (glacials and interglacials) which - if they could be dated - would reveal much about the evolution of early humans in the context of changing environmental conditions.

----- Seabed deposits

Cores extracted from ocean floor deposits reveal variations in oxygen isotopes in the shells and skeletal material of dead marine creatures, which reflect fluctuations in global temperature and the volume of the ocean.

* Temperatures from Fossil Shells 'An example of the ingenious technical work and hard-fought debates underlying the main story is the use of fossil shells to find the temperature of oceans in the distant past.' (American Institute of Physics)

----- Ice cores

A datable record of climatic change in relatively recent periods has been recovered from cores, up to 3 km long, extracted from the ice sheets of Greenland and elsewhere.

* Holocene Variability from ARCSS/GISP2 compared to other Paleo-Proxy Records (Greenland Ice Sheet Project, University of New Hampshire)

* Mount St. Helens volcano A typical volcano that has a long history of eruptions that can influence short-term episodes of climate change detectable in ice-core records (Volcano World)

4.3. Varves

Sections cut through lake beds in glacial regions reveal a regular annual pattern of coarse and fine layers, known as varves. Variations in climate produced observable differences in the thickness of sediments, and, like the patterns of variation in tree rings, this allows matches to be made between deposits in separate lake beds.

* VARVES: annually-deposited sediment '1912 Gerard DeGeer developed the Swedish Varve Chronology, the first accurate dating of the late-glacial and Holocene.' (Department of Geosciences, University of Arizona)

Tephrochronology

Deposits of volcanic ash encountered in stratified contexts on archaeological sites offer opportunities for dating.

* Tephrochronology Group 'The correlation and geochemical analysis of volcanic ash deposits (tephra) allows the identification and dating of isochronous marker horizons within sediment sequences. Tephrochronology thus provides a precise and well-established dating tool, already widely used in the study of Quaternary environmental stratigraphies.' (Research Laboratory for Archaeology and the History of Art, Oxford University)
* More on Kostenki: How Old is that Tephra? Discussion about dating of a prehistoric site in Russia where volcanic deposits originating in an eruption in Italy were encountered (K. Kris Hirst's Archaeology Blog)

4.4. Pollen (NB: pollen analysis has been superceded as a DATING method by radiocarbon since the 1950s)

Microscopic wind-blown pollen grains survive well in many soil conditions, and pollen that has accumulated in deep deposits - such as peat-bogs - can provide a long-term record of changes in vegetation; suitable samples may be collected from soils exposed by excavation, or from cores extracted from bogs.

* Pollen analysis 'Each sample can be analyzed for pollen grain and spore content, with each grain or spore being identified as the prepared slide is traversed on a mechanical stage under the high-power microscope. Then a pollen diagram, graphical expression of pollen analysis, can be constructed with consideration of sampling error.' (MSU EMuseum)

4.5. Dendrochronology

It has been recognised since at least the fifteenth century that trees produce annual growth rings - their physiology was understood by the eighteenth century - and that they could be counted to calculate the age of a tree when it was felled. Because the thickness of these rings is affected by annual climatic factors, distinctive sequences of rings may be recognised in different samples of timber and used to establish their contemporaneity.

* Wiener Laboratory for Aegean and Near Eastern Dendrochronology This site includes explanations of dendrochronology and links to research projects (Cornell University)

* Ultimate Tree-Ring Web Pages 'My goal is to make available as much information about dendrochronology as I can possibly find on the Internet, from the basics of tree-ring dating, to reference and bibliographic information, to products and supplies, to books, and more!' (Henri D. Grissino-Mayer, University of Tennessee)

* Sheffield Dendrochronology Laboratory '...has existed for over 25 years. The range of sites and types of material examined has enabled its personnel to develop high standards of expertise and professionalism, and to gain international recognition.' Informative links to methods and research projects (University of Sheffield)

* Laboratoire Romand de Dendrochronologie Beautifully illustrated Swiss site (in French) with explanatory photographs that speak for themselves.

----- The application of tree-ring dating

Unfortunately there are many problems in the direct application of dendrochronological dating. Not all tree species are sufficiently sensitive to display distinctive variations in their ring characteristics, particularly when growing in temperate climates. Wood only survives under exceptionally wet or dry conditions, and large timbers must be recovered to provide sufficient rings for valid comparisons because they rely on patterns that accumulated over several decades.

* Crossdating Tree Rings 'You will be able to interact with this presentation, including trying skeleton plotting for yourself!' (Laboratory of Tree-Ring Research, University of Arizona)

* Dendrochronology (Tree-Ring Dating) of Panel Paintings 'Many European paintings are painted on solid wooden panels or boards, typically oak for Netherlandish paintings. The wood is usually split radially so that, in ideal circumstances, a sequence of annual growth-rings from pith to sapwood is present. These sequences are then matched one against another by the dendrochronologist and compared with growth sequences whose dates are known from living trees. Absolute dates can thus be assigned to specific annual rings. Sometimes the geographic origin of a board can be determined as well.' (detailed illustrated explanation by Peter Ian Kuniholm)

5. ABSOLUTE TECHNIQUES

5.1. Radioactive decay

The successful development in the early twentieth century of radiometric methods relying upon radioactive decay for dating geological periods offered hope that a similar technique might be found to give absolute dates for prehistoric archaeology.

* What is radioactive dating? Part of a clear introduction to geological dating methods from Australian Museum, Sydney

* PRIME Lab Purdue Rare Isotope Measurement Laboratory: explanations of the principles of Accelerator mass spectrometry, and a wider look at the uses of radioacive isotopes.

5.2. Radiocarbon dating

Radiocarbon dating was one peaceful by-product of accelerated wartime research into atomic physics and radioactivity in the 1940s. The rate of decay of 14C, which has a half-life of 5730 (±40) years, is long enough to allow samples of carbon as old as 70,000 years to contain detectable levels of radioactive emissions, but short enough for samples from periods since the late Stone Age to be measured with reasonable precision.

* Radiocarbon This is the principal periodical for C14 dating - follow the links to further information and individual laboratories.

* Oxford University RLAHA Radiocarbon Accelerator Unit

* Beta Analytic 'World's Largest Radiocarbon Dating Service; AMS, Mass Spectrometry, C14, and more...' Lots of informative links from the homepage of this commercial radiocarbon dating service.

* Radiocarbon WEB-info Detailed explanations of the technique from University of Waikato radiocarbon lab, New Zealand

5.3. Presenting and interpreting a radiocarbon date

Because interpretation is so complex, all radiocarbon dates included in an archaeological publication must be presented in a standard format.

* CALIB Radiocarbon Calibration 'CALIB makes the conversion from radiocarbon age to calibrated calendar years by calculating the probability distribution of the sample's true age. Graphics and a variety of options are available through the program's menus.' (Minze Stuiver and Paula Reimer)

* Why radiocarbon measurements are not true calendar ages How radiocarbon calibration works (from Radiocarbon Web-Info)

* Der Tod startet die Stoppuhr Death starts the stop-watch: 'Everytime a living being dies a stop-watch starts ticking. Science can read this watch and thus determine the age of a find.' A dated but well illustrated description of radiocarbon dating (WebMuseen, Germany)

----- Radiocarbon samples

Most organic materials are suitable for dating; the lower the carbon content, the larger the sample needs to be.

* The Prehistory of Lums Pond: The Formation of an Archaeological Site in Delaware - Vol. II: X. RADIOCARBON ANALYSIS 'Methods: Collection and Processing: Radiocarbon samples were recovered from a variety of proveniences across the site. These included charcoal from concentrations within features; dispersed charcoal from arbitrary levels within features; dispersed charcoal from arbitrary stratigraphic levels not associated with features; and bulk soil samples from stratigraphic levels.' (Delaware Department of Transportation Archaeology Series No. 155)

----- The impact of radiocarbon dating

Radiocarbon dating has grown exponentially, and many problems and inaccuracies have been isolated and examined, some leading to major adjustments of the results. Without doubt, it has made the greatest single contribution to the development of archaeology since geologists and prehistorians escaped from the constraints of historical chronology in the nineteenth century.

* THE CONTRIBUTION OF RADIOCARBON DATING TO NEW WORLD ARCHAEOLOGY PDF file of article by R E Taylor from RADIOCARBON, Vol 42, Nr 1, 2000, p 1–21: 'The application of the 14C method to archaeological materials is generally considered to be a watershed event in the history of archaeology and, in particular, in prehistoric studies... Perhaps the most forceful statement was the view of the late Glyn Daniel that the development of the 14C method in the 20th century should be equated with the 19th century change in the Western world view that accompanied the revelation of the great antiquity of the human species...' (Delaware Department of Transportation Archaeology Series No. 155)

5.4. Potassium-argon (40K/40Ar) and argon-argon dating (40Ar/39Ar)

Potassium-argon is ideal for dating early hominid fossils in East Africa, for they occur in an area that was volcanically active when the fossils were deposited between one and five million years ago; pioneering results in the 1950s doubled previous estimates of their age.

* Chronological Methods 9 - Potassium-Argon Dating 'The Potassium-Argon dating method is an invaluable tool for those archaeologists and paleoanthropologists studying the earliest evidence for human evolution.' Clear introduction from course materials produced by Brian M. Fagan (University of California Santa Barbara)

5.5. Uranium series dating

The dating of rocks back to the Pre-Cambrian by measuring the proportions of uranium to lead or uranium to helium was possible because isotopes of uranium remain radioactive for such a long period.

* Open University Uranium-Series Facility Information on archaeological projects (Department of Earth Sciences, The Open University)

5.6. Fission-track dating

This method involves counting microscopic tracks caused by fragments derived from fission of uranium-238 in glassy minerals, whether geological or of human manufacture. In practice the most useful samples come from zircon or obsidian, which was used extensively for making tools.

* Forschungsstelle Archaeometrie Follow link to Fission-track dating (Max-Planck-Institut für Kernphysik, Heidelberg)

5.7. Luminescence dating

The physical phenomenon of luminescence may be used to date artefacts that were made from (or include) crystalline minerals which have been subjected to strong heating. The first successful application was to clay fired to make pottery, but it is commonly used now for dating flint tools that have been burnt, for example by being dropped accidentally into a fire.

* Forschungsstelle Archaeometrie Follow link to Luminescence (Max-Planck-Institut für Kernphysik, Heidelberg)

* Dating and Research Projects 'The laboratory has extensive experience of dating archaeological ceramics and burnt stones from sites in Scotland and overseas. The value of TL dating of such materials frequently lies in the association between the event being dated and an archaeologically important event in the development of the site. For example the last heating of a hearth stone dates the abandonment of a prehistoric settlement. More recently there has been a marked increase in interest in optical dating of sediments, with many groups within the Scottish Universities having application interests.' (Scottish Universities Environmental Research Centre, Luminescence Facilities)

* Luminescence dating 'Luminescence dating is a relatively new alternative approach to Quaternary chronological problems. Both quartz and feldspar rich sediments, which are otherwise undateable by conventional radiocarbon methods, can be absolutely dated within a range of 10 to 300,000+ years.' (Sheffield Centre for International Drylands Research)

* Palaeolithic tools from the surface of optically stimulated luminescence dated alluvial fan deposits of Pinjaur Dun in NW sub-Himalayas PDF file of a case-study: 'We therefore need to search for new evidence that may be available for working out a true chronology of the Sohan type tools and their sites, particularly in the absence of absolutely datable material. If in some cases, the absolute age of the surface on which some stone tools are found is known, it will certainly provide us with a lower limit to the date of fabrication/use of these tools.' (ANUJOT SINGH SONI, VIDWAN SINGH SONI, CURRENT SCIENCE, VOL. 88, NO. 6, 25 MARCH 2005)

5.8. Electron spin resonance (ESR)

Like thermoluminescence, ESR is a 'trapped charge' dating method, but it is applied to different kinds of samples, and the method of measurement is also different. ESR does not release trapped electrons, but subjects them to electromagnetic radiation in a magnetic field, which causes electrons to resonate and absorb electromagnetic power. The strength of resonance reflects the number of electrons that have become trapped since the crystals were formed.

* Forschungsstelle Archaeometrie Follow link to ESR (Max-Planck-Institut für Kernphysik, Heidelberg)

* Professor Rainer Grün: abstracts Insights into the application of ESR dating in archaeology can be gained from these summaries of works by a leading exponent; PDF files of some are available from his list of publications. (Research School of Earth Sciences at the Australian National University)

6. DERIVATIVE TECHNIQUES

Derivative methods may only be used for dating if their results can be related to a time-scale or reference curve that has been established by absolute dating methods. If it is not affected in any way by its environment the result can be described as absolute. In contrast, dating the change of one form of amino acid to another is derivative because the rate of alteration varies, and is heavily dependent on the temperature and humidity of the context where the sample has been buried.

6.1. Protein and amino acid diagenesis dating

Bones, teeth and shells contain proteins that break down after death, and the most commonly investigated products of decomposition are amino acids. Amino acid racemization dating (AAR) measures changes between these amino acids' L- and D-forms; their ratio is an indication of age.

* Amino Acid Racemization Dating in New Zealand: An Overview Large PDF file. AAR '...is used to determine relative dates of biological materials such as bone, shell and teeth and has been used in an archaeological context for over 30 years. During this time a number of significant results have been generated but many have been questioned and the technique remains controversial. In spite of this the possibility of reliable AAR dating is attractive. The technique potentially serves as an independent method for dating faunal material, which is useful in the context of providing support for chronometric information produced by other methods.' (Judith Robins, Martin Jones and Elizabeth Matisoo-Smith, Auckland University)

6.2. Obsidian hydration dating

Obsidian - a natural volcanic glass - was a popular alternative to flint for making flaked tools in many parts of the world. As soon as a fresh surface of obsidian is exposed, for example during the process of making it into a tool, a microscopically thin hydration rim begins to form as a result of the absorption of water.

* Introduction to Obsidian Hydration Studies 'Once a hydration layer has been measured, it can be used to determine the relative ages of items or, in some circumstances, can be converted into an estimated absolute age. In order to transform the hydration rim value to a calendar age, the rate of the diffusion of water into the glass must be determined or estimated. The hydration rate is typically established empirically through the calibration of measured samples recovered in association with materials whose cultural age is known or whose age can be radiometrically determined, usually through radiocarbon dating methods...' (Northwest Research Obsidian Studies Laboratory, Oregon; a number of lab reports and articles are available to download as PDF files)

6.3. Archaeomagnetic dating

The Earth's magnetic field undergoes continuous change. The position of magnetic North wanders around the North Pole, and even reverses completely to the South Pole for extended periods on a geological time-scale. From any reference point its position is measurable in terms of two components: movement up or down (inclination or 'dip') and from side to side (declination).

* Archaeomagnetism 'Archaeological materials that contain magnetic particles are kilns, pots, hearths and most sediments. Heating and cooling such materials (or depositing in air or water in the case of sediments) causes the geomagnetic field to be recorded by the magnetic particles present. This recorded magnetisation can be measured many years later and so give a date that is directly related to anthropogenic activity. The technique can be applied in the last 3000 years in the UK, however, it is not an independent method of dating and requires a reference curve to convert the magnetic direction measured into a date.' (Archaeomagnetic Dating Laboratory, Department of Archaeological Sciences, University of Bradford)

* Archaeomagnetic Analysis of a Roman(?) Kiln/Drying Oven, F159, Nosterfield Report on the application of this technique to an excavated structure in Yorkshire, England: ''A total of 13 samples of fired stone and 1 of fired clay were removed from F159 for the purpose of archaeomagnetic analysis and dating. Specimens were oriented in situ using the button method, combined with spirit levels and a sun compass. Demagnetisation tests showed that the magnetisation in the material is highly stable. The mean archaeomagnetic vector in the samples was compared with the UK Master Curve to suggest that last firing occurred in the date range 100-170A.D.' (© Archaeological Planning Consultancy Ltd)

7. THE AUTHENTICITY OF ARTEFACTS

When major museums buy items for their collections they become involved in expensive commercial dealings in the fine art market. The profits to be made encourage not only illicit plundering of ancient sites but skilful forgeries. Scientific dating techniques can provide reassurance; when what is needed is confirmation that an object is not a modern fake, rather than a precise date, full control of all the variables that affect accuracy is not necessary.

* Labor Ralf Kotalla 'Worldwide oldest private Laboratory for genuine Analyses': Thermoluminescence analysis for ceramics and cores of cast metalwork - especially to detect forgeries. Follow links to 'Analysis' and 'Articles'.

* Spectroscopic Dating and Classification of Wood PDF file: 'It is important to be able to detect the use of old wood for recently-made fakes. ... The surface layer of any wooden artefact has undergone chemical changes due to UV light and other environmental agents. Since spectroscopy is a chemical analysis, it can detect these differences. ... If an object is made of wood that is already old, both curves are nearly identical.' (Gottfried Matthaes, Wooden Artifacts Group).
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The Italian Archaeological Expedition in the Sudan 2007 (by Torino University)

Since 1970 the Italian archaeological activities in the Sudan have been sponsored by Rome University "La Sapienza", since this institution was at the time the only university in Italy to have a chair of Egyptology and to be interested in fieldwork in the Sudan. A few years ago, however, the Faculty which hosted the chair of Egyptology, along with other remarkable subjects engaged in Africa and the Near East, diversified its objectives. Eventually the chair of Egyptology was suspended, after the Director of its expedition in the Sudan, Prof. Alessandro Roccati, was appointed to a newly created chair of Egyptology at the University of Torino, thus allowing him to resume and maintain the fieldwork in the Sudan on behalf of the Centro ricerche archeologiche e scavi di Torino (CRAST) and to continue the research in the archaeological area of Jebel Barkal and to ensure the continuation of the team's activities. Otherwise a long period of experience and training would have been lost. This ensures that the present mission is the legitimate offspring of the preceding one and rooted in the same place – as it was already announced at the recent Warsaw Conference. On the one hand it was at Rome that the Tenth International Conference of the Society of Nubian Studies was held in 2002, and on the other hand it was at Torino that the International Exhibition of Nubian archaeology was displayed in 1999: both of them for the first time in Italy, and both of them under the responsibility of Prof. Alessandro Roccati. Furthermore we need not underline the importance borne for the study of ancient Egypt by the research on the Nile civilisations farther South.



Funds for the mission were granted by the Italian Ministry of Foreign Affairs and the Centro Scavi of Torino. The team was composed of some already familiar participants: Prof. Alessandro Roccati (Torino University, head of the mission), Dr. Roberto Gozzoli (Torino University, historian), Dr. Grazyna Bakowska (Rzeszow University, Poland, archaeologist): and three newcomers to the Sudan, all of them trainees from the School of specialisation in Oriental Archaeology of Rome University "La Sapienza": Dr. Claudia Micari, Dr. Massimiliano Nuzzolo and Dr. Roberta Petrilli. They ensured the necessary backing for survey and documentation. The official appointed by the NCAM was Mr. Murtada Bushara Mohammed.



It must be stressed that the objective of our university mission is not only the acquisition of new results but also the training of young people. Teaching is as much as part of fieldwork as the exploration of an ancient site.



Actually the present campaign is the sequel of the fieldwork carried out between 26th November and 23rd December 2006 on account of our Mission, by a team of geologists led by Prof. Giorgio Martinotti of Torino University, who executed a surveying in the archaeological area of the Mission's excavations at Jebel Barkal. They were assisted by Dr. Grazyna Bakowska (Rzeszow University, Poland) and Dr. Maria Novella Sordi (trainee in the School of specialisation in Oriental Archaeology of Rome University "La Sapienza"), who also tried out the study of ceramics.



Our stay lasted from 12th February till 2nd March 2007, and our activity concentrated in the building labelled B2400 lying near the (ancient) road, while further exploration of the palace B1500 was reserved as a spare activity. In fact, although the main road has meanwhile been moved across the desert and it is no longer a threat to the archaeological area, we wanted to achieve the knowledge of a rather interesting structure we came across during a protective operation of the monuments. Owing to a thin layer of rubble covering the floor, and the reduced surface of B2400, we aimed at getting a general layout of its structures within the limited time span at our disposal.



This building arose on a square platform, but it had become completely invisible on the ground, so to be traversed twice in recent years by the enclosure wall around the antiquities area built by the NCAM (which one day should be removed). Its special interest was awakened by some remains of a Greek architecture standing on it (more pieces were found this year), which may provide a terminus post quem for its dating. However, it was already overlaid in the antiquity by a well paved road in North-South direction, which points to a rather early destruction. Its lack of particular decorations (the walls were not plastered nor painted), its coarse entrance (the only one hitherto clearly detected is from the West) plead for an earlier date with reference to B1500 (the so called "Natakamani's palace"). However some typical potsherds and vessels show that the area was in use during the Meroitic period. A small fragment of pottery carved with some Meroitic signs found this year provides even inscriptional evidence.



One main achievement of this year's digging has been the discovery of a rather well preserved access from the North, in line with what was interpreted as a central court followed by a peristyle court. The much decayed condition of what was expected to be an eastern entrance has now been related to the creation of the paved road, which would have rendered such a passage devoid of use. This observation raises the question of a possible contemporariness of this paved road with the building of a Greek architecture – behind which, to the South, no passageway existed according to a careful search made in a previous campaign.



If these conclusions could be maintained, in view of the basic destruction of everything over the platform, we should consider the possibility that the platform was conceived for an earlier building. That building was later completely dismantled, so as to leave barely the platform in order to host some peculiar architecture, such as a Greek edifice. Nevertheless this older building can only belong to the (early) Meroitic period, due to its construction features, with outer walls lined with red bricks. A new mapping of the area by means of a satellite photograph points out also a parallel location with B100, another building likewise from the (early?) Meroitic period, which was excavated by Reisner in 1916. We owe the copies of Reisner's journal to the kindness of Prof. Timothy Kendall, who has already cooperated with our Mission on more than one occasion.



The new access, which was cleared to the North of B2400 is smaller than the one found on the western side, and it shows a (smaller) terrace abutting the middle of that side, ending in a short ramp perpendicular to the palace's wall, at the end of which a stone threshold lay. These features imply that this entrance was also roofed.



Although some of these features – three entrances of different size in the middle of every side of the platform - are shared by the more recent B1500 (Natakamani's palace), currently dated to the middle of the first century A.D., the latter stands out for its central and imposing position in the front of the sacred mountain. This building was much more elaborated and had equal access staircases instead of ramps. The staircase on its western side, however, was not visible from the plain and was not perpendicular to the palace's wall: it descended next to the wall in direction of B500 (Amun temple).


In B2400 the apparent parallelism between its access from the North and the close by paved road is to be stressed. At any rate, the main access - already of the former building - seems to have been the one to the West, namely the one looking towards the Palace of Natakamani. We expect to reach some better understanding of the entire layout through the tracing of (foundation) walls, which were duly recorded. Some soundings showed that the original floor next to the palace's outer wall looked like a pebbly ground.



The excavations were accompanied by the careful choice and documentation of ceramics uncovered in the different sites where the Italian Mission has been operating at Jebel Barkal. The material has been collected for several years, and at present we are organising a team for its encoding by means of informatisation. Sound results will require a longer time of study and comparison. However a provisional evaluation of forms and painted patterns refers to a period from the second century B.C. to the first century A.D. and possibly later, at least with reference to corresponding evidence from Meroe. Two reversed jars, still with their original contents of bones and some burnt material, were buried in the ground beside the eastern red brick wall closing the middle court and a mud brick wall bordering the paved road. Their location was next to each extremity, i.e. respectively South and North, of the wall.

When we arrived, we found that some heavy storms of last year had broadly damaged many restorations carried out in the excavated buildings, and these needed a number of repairs. These were operated as a by-work of the Mission also thanks to the kind collaboration of the appointed Official, Mr. Murtada. Some workmen of ours gave also a hand to cut the bushes invading the archaeological area in front of the Museum.

Finally we must assess that the friendly mood affecting the relations with the Sudanese Authorities as well as with the local people, either workmen or neighbours, has much contributed to ensure a good result of a difficult enterprise in a rather short time. May they all receive the heartily felt thanks of our entire team.

LA MISSIONE ARCHEOLOGICA IN SUDAN

Appendix: report on pottery examined

The pottery examined was found during the 2004-2007 seasons, during which two structures were being uncovered – named as B2400 and B2200.

B2200
Within the B2200 building there were mostly wheel-made ceramic pieces, some fragments of handmade ceramics were also found. About 6-7% of all finds were decorated sherds, mostly painted; less frequently they were some incised and stamped. The majority of the sherds were dated between 2nd century BC and 1st century AD.

Forms:
Fragments of cups, bowls, plates, saucers, stoppers, lids, beer jars, globular jars, pots, vases, bottles, amphorae, oil lamp, bread moulds and burners.

Motifs:
Offering-table, Hathor's emblem, rosette, ankh-sing, lotus-flower, upright leaves, connected circles, palm-branch, vine wreath, trefoil, twisted cord guilloche, stars, triangular geometric motifs, striped style.

B2400
Pottery sherds found enclosed in the building walls and floors, and other fragments spread throughout the surroundings of the building itself could be dated to the Meroitic Period (some ceramics can be dated between 2nd and 1st century BC, while other pottery in this case out of context could be dated between 1st and 3rd century AD). Moreover, some forms seem to go back to the Napatan Period.

There were wheel made and handmade ceramics pieces. In comparison with the B2200 structure there were very few painted ceramics, while incised and impressed pottery was predominant.

Forms:
Fragments of cups, bowls, dishes/plate, saucers, stoppers, lids, storage jars, globular jars, pots, basins, vases, amphorae, bread mould, klepsydrai.

Motifs:
Human figure, Lion (Apedemak), bird, ankh-sign, vine wreath, rosette, criss-cross.
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Digging for the Dream in Mound Bayou

Abstract
In March, 1998, a public excavation occurred in Mound Bayou, one of the first all-black incorporated towns in the US. At one time, Mound Bayou was a prosperous and influential community. Today, because of economic conditions, Mound Bayouans are struggling to survive and teach their youth about their important history and culture. The public dig which centered on a town lot behind the Bank of Mound Bayou and also contained their first City Hall, was aimed at involving young people in the discovery and preservation of their heritage. This paper reports on this "ground-breaking"archaeological project in the Mississippi Delta and discusses some steps for working with a descendant community.

Introduction

In March, 1998, a pubic dig was held in Mound Bayou, Mississippi. The excavation was conducted by Amy Young, Milburn Crowe, five students from The University of Southern Mississippi, Phil Carr, and, most importantly, local youth. After presenting a brief sketch of the history of this remarkable all-black town in the Mississippi Delta, a discussion of the steps in working with a descendant community are presented. The purpose is to share information about what we found that works when descendant communities participate in archaeological investigations.

Mound Bayou was established in 1887 by Isaiah T. Montgomery and his cousin Benjamin Green (Hermann 1981; Hamilton 1991). It is located in Bolivar County, Mississippi in the region known as the Delta (Figure 1). The Delta is renown for its many vast late antebellum cotton plantations (Cobb 1992). Montgomery and Green established Mound Bayou to be a haven and self-sufficient black community in the midst of the white-controlled cotton kingdom. This is especially remarkable considering the violence of the post-Reconstruction era in the Deep South, particularly in the Delta. Isaiah Montgomery and Benjamin Green and the other early pioneers of Mound Bayou wanted to create a refuge for blacks in the heart of this plantation country. In the words of modem residents, "Mound Bayou was a place where a black man could run FOR sheriff instead of FROM the sheriff."

Isaiah Montgomery was born a slave on May 21, 1847 to Ben and Mary Montgomery (Hamilton 1991). Ben Montgomery was one of Joseph Davis' (brother of Jefferson Davis) favored slaves. Ben Montgomery learned special skills (farm management, reading, and writing) and managed to accumulate some wealth. His son, Isaiah served as Joseph Davis' personal slave and secretary until Davis fled the Union Army in 1862 (Hamilton 1991).

After the war, Ben Montgomery purchased Brierfield and Hurricane plantations at Davis Bend that had been owned by Joseph Davis (Hamilton 1991). Because of financial setbacks, however, he lost the property in 1881. His son, Isaiah Montgomery, spent his life trying to bring his family back to their former state of wealth and comfort. Mound Bayou was one of the results of these efforts (Hamilton 1991).

Benjamin Green was born a slave in 1857 on the Davis Bend settlement. In 1886 he lived
with his aunt Mrs. Benjamin Montgomery (Isaiah Montgomery's mother) and learned planting and mercantile businesses. Benjamin Green was the Montgomery's mercantile manager at Davis Bend.

Benjamin Green and Isaiah Montgomery convinced other former slaves from the Davis Bend area near Vicksburg to join them in the settlement. They also attracted other black settlers to Mound Bayou, as well. Modern Mound Bayou residents feel that the success of the early colony is a clear demonstration of the potential and abilities of peoples who had been enslaved. Therefore, modern Mound Bayouans are not ashamed of their roots in slavery, but rather proud.

Mound Bayou was to be developed as part of the extension of railroads into the Deep South, and was thus placed on the Louisville, New Orleans and Texas line (Hamilton 1991:43). The Delta during the 1880s was still largely uninhabited and an untamed wilderness. Even in the twentieth century there were still vast tracts of Delta that remained a wilderness. The cotton plantations were located primarily on the Mississippi River, but the remainder of the Delta contained thick forests of hardwoods and pine trees, with numerous streams and bayous which made the area virtually impenetrable. "Poisonous snakes, wolves, panthers, and bears endangered adventurers ... and settlers" (Hamilton 1991:44). The earliest colonists of Mound Bayou were faced with the tremendous task of carving a town and community out of the wilderness with little or no economic resources. The railroad served to connect Mound Bayou with the rest of the nation.

According to Hamilton (I 991:5 0-5 1), the experiences of a pioneer of Mound Bayou named Simon Gaiter seem to typify those of most of the early settlers. Gaiter arrived in 1887 with $175, but his family did not join him until the following year. Gaiter purchased a 40-acre plot, cleared a small part, and with the timber, built a log house for his family. After the down payment of $40, the purchase of supplies, and the cost of transporting his family and his possessions to Mound Bayou, Gaiter was left with only $10.00. This was not enough to make it through the first year. Gaiter had his wife and children clear five acres of the town for $4.00 per acre and Gaiter himself cut firewood for $6.00 per cord. Gaiter's children and wife also picked cotton for $0.50 per hundredweight. Gaiter supplemented the family's diet with hunting and fishing, but recalled many weeks without meat (Hamilton 1991:50-51).

In the 1890s and in the first years of the twentieth century the population of the town and
surrounding black colony grew (Hamilton 1991:53). Isaiah Montgomery, Benjamin Green, and other pioneers not only spent time in their own family pursuits establishing businesses and farms, but also continued to contact people of means around the nation to invest in Mound Bayou, with the ultimate goal of making the town self-sufficient. In 1891 there were about 500 residents in the colony. In 1893 there were 183 living in the town proper. By 1900, the town was home to 287 residents with an additional 1500 living in the hinterlands on farms (Hamilton 1991:53). A study of the 1900 census of Mound Bayou shows 65 households. It is evident that Mound Bayouans placed a priority on education. Nearly 90% of the population could read, according to the census. The most common occupations were farmer, farm laborer, day laborer, servant, and grocer. Most of those listed as farm laborer apparently worked on their father's farm. Day laborers hired out on other farms. There were two blacksmiths in Mound Bayou in1900, two general contractors, three ministers, three carpenters, a postmaster, a stenographer, a wheelwright, a barber, two teachers, one lawyer, and one physician in 1900.

In the first years of the twentieth century, a prominent black businessman, Charles Banks, arrived in the community and founded the Bank of Mound Bayou. By 1910 the pioneers of Mound Bayou had succeeded in transforming the little community into a thriving town of 500 people, and many more in the hinterlands, with thirteen stores, six churches, a train station, a telephone exchange, and a weekly newspaper. It appeared that the dream of Isaiah Montgomery and the other early settlers had been realized (Hermann198 1). President Theodore Roosevelt named Mound Bayou "The Jewel of the Delta" and the town had the backing of Booker T. Washington and many other prominent Americans. Various industrial endeavors were established in the town. These included several cotton gins and a cotton oil mill. The cotton oil mill was erected as an additional economic boost to the economy of Mound Bayou.

Mound Bayouans understand that their unique history has also given them a unique perspective. Mound Bayou has ALWAYS had black officials like mayors, sheriffs, school board members, aldermen, and police, so that the fears associated with dealing with the white counterparts has been somewhat subdued in local residents. They recognized that black folks had much to fear from whites outside of town, but they have never really felt that once black officials are in place that all problems are automatically solved. Also, the everyday oppression felt by many black Mississippians in the early part of this century were not the norm for Mound Bayouans, however, residents could never remain shielded from the harsh outside world.

More than anything, Mound Bayouans feel that they have a special story to tell and their town holds a very special place in local, state, and national history. They feel that their town can be a source of pride for many Americans, not just Mound Bayouans. They also strongly feel that their youth need to be exposed to their own history and culture, but because of encroaching economic conditions, this is becoming more and more difficult. Mound Bayouans are proud of their history and want to share it. Also, because Mound Bayouans do not want Isaiah Montgomery's dream to fade, the project was entitled, "Digging for the Dream: Archaeology at Mound Bayou."

To our knowledge, this is the first archaeological project designed and implemented by a black community. The public outreach plus the involvement of the community in discovering and interpreting their past, then relating that history to outsiders makes this project another example of the pioneering efforts of the citizens of Mound Bayou.

Working with Descendant Communities

Involvement of descendant communities is an increasingly visible topic in historical archaeology (McKee 1998; McDavid 1997; Derry 1997; Blakey 1997; Singleton 1997). Within African-American archaeology the issue of involving descendant communities has gone beyond an interesting, and possibly productive, idea to a necessity. The political, social, and economic effects of archaeological investigations (and the resulting interpretations) on the descendant community and the entire nation must be considered by archaeologists (Blakey 1997). Suggestions by archaeologists for involving descendant communities have run the gamut from informing these groups after the fact (e.g., give a public slide presentation), to having descendant communities involved in earlier stages of research (Edwards-Ingram 1997). Further, many archaeologists have been confronted by difficulties trying to involve descendant communities in the archaeological research (McDavid 1997; Derry 1997). Clearly, involvement of descendant communities is complex, time consuming for archaeologists, but also very important in African-American archaeology.

This remainder of this paper describes the process, which is on-going, of public archaeology in Mound Bayou, Mississippi. The effort is a sustained collaboration between a professional archaeologist and the local citizens. We will outline the steps we have taken, and the issues we have faced to accomplish a public dig.

The Steps

The archaeology at Mound Bayou began as a chance encounter between the two authors of this article. Mr. Crowe is a native and historian of Mound Bayou. Amy Young met him as he served as the President of the Mississippi African American Historic Preservation Council. Crowe invited Young as soon as he understood her research area was African American archaeology. Crowe had been thinking about the possibility of archaeology in his town.

What made this first step easy was that Mr. Crowe already had some understanding of historical archaeology, which is remarkable in itself. He had met Theresa Singleton when she was involved in "Digging the Afro-American Past"conference in nearly a decade ago. While that conference was held in Oxford, Mississippi, it also included a tour of Mound Bayou. Most non-archaeologists have no understanding of the profession of archaeology and often equate archaeology with Indiana Jones. Without a basic understanding of the potential and limitations of modern archaeology, collaboration between professional archaeologists and others is very difficult.

Despite the knowledge that Mr. Crowe had an understanding of historical archaeology, when Young first visited Mound Bayou, she made a slide presentation of my work on other African-American sites so that he and other local residents might know something about the kinds of information we obtain in our work. This was very important because it made the descendant community aware of the potential and the limits of archaeology. This step, educating the descendant community, is absolutely critical for public archaeology and for involvement of a descendant community in archaeology. It is somewhat unfortunate that non-archaeologists have such a limited understanding of archaeology and often equate it with treasure hunting and Indiana Jones.

During this first visit, Mr. Crowe and other residents began educating Young about the history of their town. The history presented in the first part of this article is the story of Mound Bayou from the perspective of local residents. All referenced material was checked with residents for accuracy. Learning the history from the perspective of the descendant community was the second step for the archaeologist in working with a descendant community. In this case, because of the pride Mound Bayouans feel for their history and culture, this second step was also easy. Understanding the history and the source of pride that Mound Bayou provides to residents was critical for the archaeologist who was often reminded by the residents that history is a very personal thing and that archaeologists are actually digging up (through excavations and through interviews) intimate aspects of their past. Interestingly, while Young was taught the history of Mound Bayou, she also learned of the diversity of opinions within the community and how this affects modern cultural traditions like their annual Heritage Festival. Recognizing the diversity within a descendant community is the third step in working with a descendant community. For example, there are Mound Bayouans who are descended from the original pioneers. There are Mound Bayouans who are descended from later immigrants. This is a source of potential conflict, even if it is only friendly competition. Knowledge of the history and culture of another community from the perspective of the descendant community is also critical for a successful project.

Once it was decided that a dig was to take place then the fourth step was to find the right site. Because of the potential divisiveness within the community based on descent from early pioneer or later immigrant, Young encouraged a focus on a site with which all Mound Bayouans could identify. In other words, we decided not to excavate at the home of one of the founding families, but on a public or commercial site.

In this case, the choice was relatively simple. Mound Bayouans recognize that they have several important buildings, including the Bank of Mound Bayou constructed in 1904 by Charles Banks, a later immigrant. The old bank building is in a state of disrepair because the current owner cannot afford to fix it. The Mound Bayou Historic Preservation Council hopes eventually to acquire the building and obtain funds to stabilize and reconstruct it. Some hope it can be used as a cultural center.

The Bank of Mound Bayou is a two story brick structure, listed on the National Register of Historic Places standing on the corner of West Main and Green streets (Lot 1,Green's Square). The first floor contained the bank, but the second story held offices, including an office of a physician, Dr. Scott Harris, and offices of the Mound Bayou Oil Mill. The building served as the headquarters of the Knights and Daughters of Tabor, a black fraternal organization aimed at helping widows and orphans and supporting black business endeavors. Charles Banks organized the Mississippi Negro Business League as a chapter of Booker T. Washington's national organization, also located in the Bank of Mound Bayou (Hermann 198 1). The building occupies almost the entire lot, and it was thought that Lot Two may contain refuse from the building as it was vacant until 1919 or 1920. The refuse may help in understanding the daily activities that took place in the bank building, and many of these activities are associated with the early organization and business activities of the town.

The lot on which we excavated, besides being immediately adjacent to the Bank of Mound Bayou was eventually the site of the first City Hall and Mayor's office. The building which served as the first city hall was constructed in 1919 or 1920 by Benjamin A. Green, Benjamin Green's son and first child born in Mound Bayou. Benjamin A. Green served as Mayor of Mound Bayou from 1920 until around 1970. All of these factors made the lot ideal for an archaeological excavation. Choosing the site together with the descendant community is absolutely necessary so that the archaeologist has the support of residents.

Many residents of Mound Bayou felt that the local youth had a poor to marginal understanding of the history and culture of Mound Bayou. They felt that it was necessary to involve young people in the archaeological project. Thus the public aspect of this project was born. We decided where to dig and that this was to be a local effort. Crowe and Young wrote a grant proposal to fund a public dig and because it must, involve school-age children, the excavation was scheduled for Spring Break. The fifth step in working with a descendant community is to directly involve local people in the work. In this case, the youth of Mound Bayou excavated with us.

The decision to involve the youth of Mound Bayou in the archaeology was one of the wisest decisions we made. Instead of strangers coming into town to excavate, it put control in the hands of the descendant community. Furthermore, in a community that has experienced continual oppression from whites and made some local residents reluctant to share memories, it opened the door to additional information in the form of oral histories shared more with the youth than with strangers.

After the excavation and the processing and identification of the artifacts, the story of this public dig and what we found will be disseminated throughout Mississippi in the form of a traveling exhibit of "Digging for the Dream in Mound Bayou." The last step in working with a descendant community is to make sure all interpretations are approved by that community. In this case, Young made a subsequent visit to Mound Bayou to meet with the Mayor and the Historic Preservation Council where she laid out ideas for the exhibit, which they commented upon and approved. Most of her suggestions were greeted warmly and the input added detail and richness to the exhibit. This last step is the most important of all, because who owns the story of Mound Bayou but Mound Bayouans.

The Digging for the Dream project culminated in a final public forum to disseminate the findings during Mississippi's Archaeology Week. Young gave a brief slide presentation of the dig, and Theresa Singleton came and talked about the place of Mound Bayou in state, National, and international history. Dr. Alferdteen Harrison, from Jackson State University also spoke, as did the mayor of Mound Bayou, and Mr. Crowe.

Conclusions

The public excavations at Mound Bayou were a tremendous success for a number of reasons. First, Mound Bayouans initiated the project and had control over the site and the subsequent interpretations. Second, a dialogue between Mound Bayouans and professional archaeologists was facilitated through mutual interests and through involvement of the youth of Mound Bayou. Third, involvement of the youth of Mound Bayou in the excavations tended to open the doors (and memories) to outsiders. In this way, elderly residents felt they were sharing their memories and oral histories with their younger residents rather than outsiders who might not understand. Third, Mound Bayouans are proud of their history and want to share this history with everyone. They believed that archaeology would be an effective way of gaining the attention of the public to educate them about Mound Bayou.

Because of the work of the volunteers, those who excavated and those who shared their knowledge, we now know more about the activities that took place within the Bank of Mound Bayou and City Hall. We have a secure date of ca. 1920 for the construction of the city hall building. But perhaps even more important, the youth of Mound Bayou have a deeper appreciation of the history of their important community and can now share that history with others across the state.

More than anything else, working with descendant communities in discovering and uncovering the past makes the work or archaeologists very relevant. Most archaeologists want to make a difference through their work and this is a very rewarding way to make a difference.

Another reward of working for a descendant community is the access to oral history. While there is little in surviving documents concerning the African-American experience in the United States, especially written by blacks, there is a wealth of information in the form of oral history. When the descendant community is in control of a project, they feel ready to share the crucial information in oral history with the archaeologist.

The overall success of the "Digging for the Dream" project is, in part, attributable to the unique character and culture heritage within the community of Mound Bayou. This case study of working with descendant communities, therefore, is ideal. However, in archaeological and cultural investigations of black life in and around Natchez, Mississippi, the same basic principles were adopted and also have been successful. One of the biggest problems to overcome in working with African-American descendant communities is the perspective shared by part of the community that there is something shameful in the history of slavery. In other words, there is some degree of shame within the black community concerning slavery and descent from slaves. In the case of Mound Bayou, this was not an issue. However, through trust, respectful discussion, and mutual education, this can be overcome. Building trusting relationships, though, is very time consuming for the archaeologist and for members of the descendant community. One final step in working with descendant communities is do not force any beliefs or issues on that community until there is a general willingness to be open and trusting in the exchange of information.

References

Derry, Linda 1997 Pre-Emancipation Archaeology: Does It Play in Selma, Alabama. Historical Archaeology 31(3):18-26.

Edwards-Ingrarn, Ywone 1997 Toward "True Acts of Inclusion:" The "Here" and the "Out There" Concepts in Public Archaeology. Historical Archaeology 31(3):27-36.

Franklin, Maria 1997 "Power to the People:" Sociopolitics and the Archaeology of Black America. Historical Archaeology 31(3):36-51.

Hamilton, Kenneth M. 1991 Black Towns and Profit: Promotion and Development in the Trans _Appalachian West, 1877-1915. University of Illinois Press, Urbana.

Hermann, Janet Sharp 1981 The Pursuit of a Dream. Oxford University Press, New York.

McDavid, Carol 1997 Descendants, Decisions, and Power: The Public Interpretation of the Archaeology of the Levi Jordan Plantation. Historical Archaeology 31(3):114-132.

McKee, Larry 1998 Some Thoughts on the Past, Present, and Future of the Archaeology of the African Diaspora. Paper presented at the Plenary Session "Where Are We and Where Do We Need to Go" at the annual meeting of the Society for Historical Archaeology, January 1998, Atlanta, GA.



Written by:
Amy L. Young (Department of Anthropology and Sociology The University of Southern Mississippi)
Milburn J. Crowe (Mound Bayou, Mississippi)
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George Washington’s Blacksmith Shop

During 1930s, Morley Williams, a landscape architect from Harvard University, was conducting historical and archaeological research at the plantation and he supervised the initial excavations at George Washington’s Blacksmith Shop. The Mount Vernon Ladies’ Association was interested in the smithy as a possible candidate for reconstruction in the early of this decade. Williams and the Association were interested in identifying structures and other features present during 1799, the year of George Washington’s death, to enhance the authenticity of the historic house museum. Besides numerous documentary references to the shop, the structure was depicted on the Vaughan plan drawn in 1787. At some point a brick Ice House was constructed at the site of the Blacksmith Shop and debate over the age of this structure, the date of the demise of the smithy, and the Blacksmith's Shop size and appearance were the goals of this and subsequent excavations conducted over the next half-century.


Morley Williams excavated at the Blacksmith's Shop during the 1930s.

The Association sought physical evidence for the exact location and appearance of the Blacksmith's Shop, as well as about the activities undertaken at the Blacksmith's Shop to support a reconstruction of the building and interpret blacksmithing at the museum, an important component of the plantation economy. Besides Morley Williams’s work in the 1930s, restoration architect Walter Macomber excavated at the site during the 1950s and 1960s as did the Virginia Research Center for Archaeology during their survey and archaeological assessment of the plantation in 1984 -- 85. Dennis J. Pogue, Mount Vernon’s first Chief Archaeologist, completed this final excavation in 1989.


The base of the brick blacksmith's forge.

The archaeological excavations revealed considerable structural evidence for the shop. This included a fragmentary brick foundation that is interpreted to be the base of the forge, and two sections of masonry, running east-west and 16 feet apart, that are remnants of the foundation for the long walls of the shop. The forge base has a characteristic void in the center, marking the location of the fire box. A portion of the forge base and most of the shop’s foundations were disturbed by later construction, including erecting a mid-19th century ice house overlapping with the shop’s footprint.


Postholes such as these show the location for fences near the Shop.

The archaeological evidence indicates that the shop was 16 feet in width, but the other dimension cannot be determined. On the Vaughan plan the building measures roughly 12 by 40 feet, but this is clearly an example of artistic license. The depiction of the shop shown on the earlier Vaughan sketch appears more likely to be closer to the actual dimensions, as it is shown as roughly 18 by 24 feet.


The Vaughan plan depicts the Blacksmith Shop (top left) as 12 x 40 feet. Click image to see the 18 x 24-foot Shop on Vaughan's earlier sketch (#13).

Two rows of post holes and molds mark the location of two fencelines, each of which intersected with a corner on the east end of the shop. The fenceline connecting with the southeast corner turned to form a work yard on that side of the building, turning again to run parallel to the north lane and ultimately connecting with a corner of the Servants Hall, 160 feet distant, just as indicated on the 1787 Vaughan plan. The distance between the square post molds was six feet, and the view of the site shown in a painting executed by Edward Savage circa 1792 indicates that the fence was well finished and painted white. The other fenceline ran from the northeast corner of the shop to the north along the edge of the lane. The round postmolds marking this fence were nine feet apart, suggesting that it was a more rustic, post-and-rail fence. This fence appears to have been replaced by the time that Savage made his painting, as his depiction shows a white fence connecting with the northwest corner of the building, matching the one on the other side of the shop.


This painting from c. 1792 provides important evidence for the Blacksmiths'' Shop and the two fences.

The resulting picture of the Blacksmith's Shop is of a modest structure, supported by a brick foundation, upon which a wooden frame, clapboard siding, and shingled roof were erected. The Savage painting and plantation records indicate that the shop was unpainted, suggesting that it was considered to be a more utilitarian structure than the other outbuildings along the lane, with their white-painted walls and red-painted shingles. The adjoining fenced yard would have served as a handy general work area, being especially useful when repairing large items such as wagons and carriages, and bulky agricultural equipment. Great quantities of coal, slag, and other refuse were found within the yard area, testifying to the common practice of the day of disposing of rubbish, even very messy materials such as smith’s waste, very near their source.


An artist's rendering of what the Blacksmith's Shop may have looked like.

The bottom courses of a robbed brick wall footing were found abutting what is interpreted as the northeast corner of the Shop. This is likely the terminus of the brick Ha-Ha wall that encircled the east lawn of the Mansion, and which is known to have been in existence by 1785. This portion of the Ha-Ha wall was removed and relocated in the 1890s during its reconstruction. At that time the route of the wall was altered to terminate at the corner of the brick Ice House. When the Blacksmith's Shop was demolished, the Ha-Ha would have ended in space, necessitating its extension to the west, where it probably connected with a fence or wall running along the north lane. The Currier plan of 1855 shows the north Ha-Ha connecting with a short section of wall or fence just north of the ice house.


The foundation of the earlier Ha-Ha wall.

Based on the archaeological evidence Mount Vernon reconstructed the Blacksmith Shop in 2009. Today, this important plantation craft is once again practiced at the site. The numerous artifacts and historical information discovered during the investigations help interpret the space for our visitors.
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Photogrammetry for the Preparation of Archaeological Excavation (Part II)

4. PHOTOGRAMMETRIC DATA PROCESSING

4.1 Multi-image photogrammetry

Photogrammetric solutions (Grussenmeyer et al., 2002) are either based on the processing of single images (e.g. image rectification of plane objects), stereoplottings (for stereopairs of photos), or multi-image restitutions when a set of convergent photos of an object is available. The last solution has been chosen for our project in order to process in one block the sets of photos taken from the different types of cameras. We used the PhotoModeler software package from EOS System (Canada), well known for its applications in close range photogrammetry, architecture and archaeology.

The preparation steps in order to process the images were the following:
- definition of the “camera” file for each type of camera: the « camera calibrator » module of PhotoModeler has been used for the calibration of the digital cameras;
- for the archive images, an approximate camera file has been edited (camera with four fiducial marks) for further “on the job calibration”;
- edition of the control point table (from the geodetic survey);
- scan of the film or paper-based images (for the set of archive images and the color slides from the Nikon F3 camera).

The basic steps in this type of project performed with PhotoModeler are :
- choice two or more overlapping photographs from different angles of the object ;
- use the point and line tools to mark on the photographs control and tie points;
- reference the points by indicating which points on different photographs represent the same location on the object (homologous points);
- process referenced data to produce 3D model;
- check the adjustment and view the resulting 3D model in the 3D viewer ;
- extract coordinates, distances, curves, surfaces, textures etc. within PhotoModeler;
- export the 3D model to rendering, animation or CAD program.

4.2 Calibration of the cameras

Four types of images are used for this project:
- images from a Nikon Coolpix 5000 camera used in the extreme positions of the zoom (7mm and 21mm). This camera was calibrated in the two positions using the calibration grid proposed in the PhotoModeler software (module "camera calibration");
- images taken with a traditional reflex camera Nikon F3, equipped with a Nikkor 55mm objective. The calibration was carried out like previously after scanning the slides of the calibration grid;
- images (prints or copies of film, see paragraph 3.1) of 1930-1936 scanned with a resolution of 900dpi: unfortunately no photogrammetric information on the characteristics of the cameras used has been found. Several types of glass-platesbased cameras with focal distances of 20 to 30cm were used at that time for the acquisition of aerial and terrestrial views (Roussilhe, 1936). The focal length of the camera used for this archive images is written on the border of the image (26 cm) and the original size of the images (glass plates in the 1930’s) was supposed to be 24 cm x 18 cm.

4.3 Adjustment of the block of the images of 2003

More than 130 images were realized in spring 2003 with the Nikon F3 and Nikon Coolpix cameras (a hundred images on the ground and about thirty in the helicopter). A first block of 18 oblique views of the castle was oriented in June 2003 using the control points materialized on the ground by targets (figure 6). Standard deviations of about 10 cm on the co-ordinates of the points measured on the images have been obtained. We then selected in this project a set of points simultaneously visible on the images of 1931-1936, in order to define approximations of the photogrammetric parameters, and to calculate a block based on a selection of these archive images.

4.4 Adjustment of a block of archive images

Initially we selected 5 oblique photographs (approx. scales of 1/1000 to 1/2000) in order to document archaeological vestiges of the North and West parts (Grussenmeyer & Yasmine, 2003). The approximate values of the internal and external orientations of the archive images have been computed within the module "process & autocalibration" of PhotoModeler with the help of control points defined in §4.3.

4.5 Merger of the two projects and preparation of the restitution

At this stage, the two separately calculated projects are referred to the same reference system. The process of merging (of several projects) proposed in the PhotoModeler software allows the restitution of three-dimensional elements simultaneously on the photographs of 1936 and 2003, and to superimpose and display these results within a unique project.




Figure 9. Overview of the camera stations and the block configuration after the exterior orientation. At the right: a vertical view of 1935 allowing the location of the camera stations.

4.6 Addition of other images in the project

Depending on the parts of the castle to model, any other recent or archive image can be imported and oriented within the project by identification of homologous points.

5. PREPARATION OF ARCHAEOLOGICAL EXCAVATION

From the block of images previously oriented, the restitution initially carried out in 2D in Autocad (e.g. fig. 7 and 8) will be enriched by a 3D restitution corresponding to the objectives of the documentation. We are then able to calculate and draw the visible structures from the aerial and terrestrial photographs of 2003 by digitalizing on the images. One will proceed in an identical way on the archive photographs to measure the
archaeological structures currently covered by the remains of the war currently embanked or destroyed (fig. 10), or to plot in 3D parts of the castle (see §6).




Figure 10. Restitution of the embankment areas: on the left, the boundary of the embankment is marked on a photo of 2003 and on the right, the corresponding surface is projected on an archive photo of 1936

The superposition of the two restitutions makes it possible to highlight the areas of interest (figures 10 and 11) for archaeological work and to estimate work of civil engineering (fill, cubature, rebuilding, etc).

Moreover, the restitution of the site in wire frame and surface model can be supplemented by the addition of textures coming either from the images of 1936, or of those of 2003. From the resulting 3D photomodels, orthophotos can be calculated for the two periods, as e.g. for the frontages of the castle or the installations around the site covering the archaeological structures (fig. 11).

1936

2003
Figure 11. Archaeological structures are measured on the archive images of 1936 and the corresponding surface is shown on the photos of 2003


Figure 12. Example of orthophoto of the archaeological structure (computed from an archive image of 1936)

6. RESTITUTION OF THE HISTORICAL STRUCTURES NOWADAYS DISAPPEARED

The aim of the restitution is to help the consultant to establish the framework of the excavation and restoration tasks, by showing the destroyed historical structures.
The study is currently focused on different parts of the castle (figure 13). For some of them (as courses of bricks or stoneworks ”label B”), a 3D restitution of both archive and recent images is possible.
Parts recovered by embankment are modelled from only archive images (watering place “label A”, counterscarp “label C” and archaeological remains on the western part of the castle “label D”).


Figure 13. Vertical archive view showing some studied parts


Figure 14. Recent image showing the surroundings of the castle and the current constructions

7. CONCLUSION

This project shows the importance of photogrammetry within the framework of 3D documentation of the castle of Beaufort, for the development of the site and the landscape. By using the old aerial photographs taken by French air force of the Levant between 1931 and 1936, a comparative restitution makes it possible to locate in a precise way the visible archaeological structures on the archive photographs. This documentation helps the consultant to establish the framework of the excavation and restoration tasks by showing the destroyed historical structures. A photogrammetric restitution of the whole set of photographs carried out in April 2003 is planned in the future, as a preparation of the restoration of the castle and its surroundings. The contractor who will be in charge of this work will then have all information to release the great quantity of fill around the castle, in order to preserve intact the historical and archaeological structures which would be still in-situ below the embankment.
Such a project shows also the interest of a cooperation between the architect and the photogrammetry expert for both simple and complex tasks. On the one hand, the orientation process combining different kind of archive and digital images requires scientific tools and experience in the handling of images with different geometry. On the other hand, the photogrammetric documentation (in this project one day only was enough for the aerial and terrestrial images) as well as the restitution work can easily be done by the architect.

8. REFERENCES

References from Journals:
Grussenmeyer, P., 2003. Photogrammétrie architecturale et modélisation 3D du patrimoine. Revue de l’Association Française de Topographie, 2e trim. 2003, N°95, p.30-36.

References from Books:
Deschamps, P., 1939. Les Châteaux des Croisés en Terre Sainte II: La Défense du Royaume de Jérusalem, étude historique, géographique et monumentale, vol. "Album", Bibliothèque Archéologique et Historique, Tome XXXIV, Paris, Librairie Orientaliste Paul Geuthner, Plate LV.

Grussenmeyer, P., Yasmine, J., 2003. The Restoration of Beaufort Castle (South-Lebanon): A 3D Restitution According to Historical Documentation. In XIXth CIPA International Symposium, Antalya, Turquey. Sept. 30th. Oct 4tht, 2003. ISPRS International Archives of Photogrammetry, Remote Sensing and Spatial Information Systems Vol. XXXIV-5/C15 ISSN 1682-1750 pp. 322-327.

Grussenmeyer, P., Hanke, K., Streilein, A., 2002. Architectural photogrammetry. Chapter in « Digital Photogrammetry ». Edited by M. Kasser and Y. Egels, Taylor & Francis, pp. 300-339.

Huot, J.-L., Salem Kardous, A., 2001. Photographies du Levant. Institut Français d’Archéologie du Proche-Orient, Beyrouth, Liban, 165 pages.

Philipson, W.R. (Editor), 1997. Manual of Photographic Interpretation, 2nd Edition. Edited by the American Society for Photogrammetry and Remote Sensing, Bethesda, Maryland, 689 pages.

Roussilhe, H., 1936. La photogrammétrie et ses applications générales, Tomes 1 et 2. Encyclopédie industrielle et commerciale, Librairie de l’enseignement techniques, L. Eyrolles (Paris).

References from Other Literature:
Bessac J.-C. et Yasmine J., 2001. Etude préliminaire des chantiers de construction du château de Beaufort, in BAAL, N°5, p.241-320.
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