Archaeology Wordsmith

archaeology editor/writer providing solutions for busy archaeologists

Results for emic:

chemical analysis: CATEGORY: technique
DEFINITION: The main use of chemical analysis in archaeology has been the identification of trace, major, and minor elements characteristic of particular sources of raw materials such as obsidian. The methods include X-ray fluorescence spectrometry, optical emission spectrometry, atomic absorption spectrometry, spectrographic X-ray diffraction, and neutron activation analysis. This information can be useful in the study of technology, trade, and distribution.
chemical anomaly: CATEGORY: technique
DEFINITION: Any change in the chemical constituency of the soils underlying a habitation, creates by the common activities of human beings.
emic: CATEGORY: term
DEFINITION: A term referring to anthropological concepts and distinctions that are considered meaningful, accurate, or appropriate to the participants in a given culture. It involves an analysis of linguistic or behavioral phenomena in terms of the internal structure of a particular culture.
geochemical analysis: SYNONYM: geochemical survey
CATEGORY: technique
DEFINITION: An investigatory technique which involves taking soil samples at regular intervals from the surface of a site, and measuring their phosphate content and other chemical properties to determine the natural separation and concentration of elements by Earth processes.
systemic context: CATEGORY: technique
DEFINITION: Behavioral system wherein artifacts are part of an ongoing system of manufacture, use, reuse, and discard
absolute dating: SYNONYM: chronometric dating; absolute dates; absolute chronology; absolute age determination (antonym: relative dating)
CATEGORY: chronology; technique
DEFINITION: The determination of age with reference to a specific time scale, such as a fixed calendrical system or in years before present (B.P., BP), based on measurable physical and chemical qualities or historical associations such as coins and written records. The date on a coin is an absolute date, as are AD 1492 or 501 BC.
amateur: CATEGORY: term
DEFINITION: A person actively interested in archaeology but who has not received advanced academic training in the field; also those who have studied but do not pursue work in the field.
apse: CATEGORY: structure
DEFINITION: Semicircular end of a Classical building or Christian church.
archaeological chemistry: SYNONYM: archeological chemistry
CATEGORY: branch
DEFINITION: The application of chemical theories, processes, and experimental procedures to obtaining archaeological data and to solutions of problems in archaeology. This field includes laboratory analysis of artifacts and materials found in archaeological context.
archaeometry: SYNONYM: archaeological science
CATEGORY: branch
DEFINITION: The large field of work that entails the physical and/or chemical analyses (measurement) of archaeological substances, their constituents, ages, residues, etc.
atomic absorption spectrometry: SYNONYM: AAS
CATEGORY: technique
DEFINITION: A method of analysis used to determine the chemical composition of metal artifacts -- especially copper -- and non-metallic substances such as flint. It measures energy in the form of visible light waves and is capable of measuring up to 40 different elements with an error rate of around 1 percent. It is not a completely nondestructive technique, since a small sample must be removed from the artifact (between 10 mg. and 1 g., depending on the concentration of the elements). The sample is first dissolved and then atomized in a flame. A beam of light, of carefully controlled wavelength, is shone through the flame to a detector on the other side. The light takes a defined wavelength corresponding to the emission wavelength of the chosen element. The atoms of that element in the sample therefore absorbs a proportion of the light, measured with a photomultiplier, and a comparison of the intensity of the light with that which has not gone through the sample shows the extent of the absorption, thus providing an estimate of the amount of the chosen element in the specimen. One of the method's drawbacks is that a separate measurement (and a different hollow cathode lamp) is necessary for each element, so that analysis for a large number of elements is time-consuming. There are also problems of contamination with the high dilutions necessary for elements present in high concentrations, so that the method is used for the analysis of minor elements and trace elements rather than for major elements. The results are generally more accurate than those obtained using optical emission spectrometry and the technique's use will probably increase, especially for the identification of sources of metal ores through the recognition and quantification of the trace elements.
basilica: SYNONYM: [Greek 'royal building']
CATEGORY: structure
DEFINITION: Originally a royal palace which consisted of a large oblong building or hall with double colonnades and a semicircular apse at the end, used for a court of justice and place of public assembly. It formed one side of the forum or marketplace. The term owes its original meaning to the fact that in Macedonia the kings, and in Greece the archon Basileus dispensed justice in buildings of this description. The Romans, who adopted the basilica from those countries, used it as a court, a branch of the forum, etc. The first basilica was built at Rome, 182/184 BC. One such building is the Basilica of Maxentius, which has survived in the ruins of the Forum in Rome. Its aisled-hall plan of which was adopted by many early Christian churches. The form of construction remained popular for a variety of religious purposes in Rome, Ravenna, and North Africa from the 4th-12th centuries. Constantine, the first Christian emperor, constructed several basilican churches in the 4th century, including the first St. Peters.
beta-ray backscattering: CATEGORY: technique
DEFINITION: A non-destructive physical method of chemical analysis which, though limited in its application, has been used successfully to determine the lead content of glass and glaze. A specimen is subjected to a beam of electrons from a weak radioactive beta source and some electrons are absorbed while others are backscattered" from the surface of the sample and can be counted with a Geiger counter. The percentage of electrons backscattered depends on the atomic number of the elements making up the surface layer of the artifact. Therefore if an element with a high atomic number is known to be present (e.g. lead) an estimate can be made of its concentration. The equipment cannot distinguish between high concentration of elements with medium atomic numbers and low concentrations of elements with high atomic numbers. The equipment cannot sense very small amounts of an element. Factors such as the thickness of a glaze affect the amount of backscattering. The technique carries advantages in its cheapness and portability of the equipment and is considered a useful technique for analyzing material like glass."
Black Death: CATEGORY: term
DEFINITION: A particularly severe outbreak of plague which crossed Europe between 1347 and 1351 AD, probably a combination of bubonic and pneumonic plagues. It took a greater toll of life than any other known epidemic or war up to that time. A rough estimate is that 25 million people in Europe died from plague during the Black Death. The population of western Europe did not reach its pre-1348 level until the beginning of the 16th century.
bog burial: CATEGORY: term
DEFINITION: Areas where human bodies are found in peat bogs in Scandinavia and northern Europe, including more than 160 from Denmark, and which are remarkably well-preserved. The chemicals in the peat preserve the bodies, which allows archaeologists to study aspects of past life, including the soft tissues of the bodies themselves and the contents of the stomachs. Burials and ritual deposits were interred in these bogs in antiquity, especially during the Bronze and Iron ages.
bone dating: CATEGORY: technique
DEFINITION: Any of a serious of methods of analyzing bone samples, especially by measuring fluorine, uranium, nitrogen -- also called the FUN technique -- or by using stratigraphy. Human remains may be compared with animal bone or fossils found in the same strata. Relative dates may be obtained form time-related chemical changes which occur in bone, especially in fluorine, uranium, and nitrogen. Still, the most commonly used is radiocarbon dating because both the collagen and mineral components of bone are dateable.
Burzahom: CATEGORY: site
DEFINITION: A Neolithic site in the Vale of Kashmir with phases of occupation dating from c 3050 BC to the 3rd-4th centuries AD. Deep pit dwellings are associated with ground stone axes, bone tools, and coarse gray burnished pottery. These characteristics plus the absence of blades, use of pierced rectangular knives, and association of dog skeletons with human burials, all seem to point to connections with central and northern Asia, as Mongolia, rather than with the rest of the Indian subcontinent. Hunting seems to have been the main basis of the economy. Phase II has houses of mud and mudbrick and Phase III has a group of large stones arranged in a rough semicircle.
Carnac: CATEGORY: site
DEFINITION: A village in western France near the Atlantic coast that is the site of more than 3,000 prehistoric stone monuments of the alignment type. These menhirs are arranged in three groups of 10-13 parallel rows, which ended at semicircles or rectangles of standing stones. The single stone menhirs and multistone dolmens were made from local granite and are worn by time and weather and covered in white lichen. The area also has a series of long cairns of mid-Neolithic to Early Bronze Age which covers funerary chambers and secondary cists. The grave goods included polished axes of rare stones such as jadeite and fibrolite, stone boxes containing charcoal, cattle bones, and pottery. The area was clearly an important ritual center, venerated by the Bretons until fairly recent times, and adopted by the Romans for religious purposes. Christians added crosses and other symbols to the stones. In 1874, James Miln uncovered the remains of a Gallo-Roman villa one mile east of the village. The Musée Miln-Le Rouzic in Carnac has an important collection of artifacts.
cavea: CATEGORY: structure
DEFINITION: The concave-shaped auditorium of an ancient open-air theater, which was often a semicircle of stone benches rising in tiers. A cavea might be divided, depending on the size of the building, into 1-3 distinct tiers, called upper, lower, middle (summa, ima, media cavea).
Chalcolithic: SYNONYM: Chalcolithic period; Eneolithic, Copper Age
CATEGORY: chronology
DEFINITION: Literally, the Copper Stone Age" a period between the Neolithic (Stone Age) and the Bronze Age from 3000-2500 BC in which both stone and copper tools were used. It was a transitional phase between Stone Age technology and the Bronze Age and an increase in trade and cultural exchanges. The term is much less widely used than other divisions and subdivisions of the Three Age System partly because of the difficulty in distinguishing copper from bronze without chemical analysis partly because many areas did not have a Chalcolithic period at all."
chromatography: CATEGORY: technique
DEFINITION: A technique of separating colored substances and analyzing their chemical structure by chromotographic adsorption. Differences in the rate of movement along a liquid or solid column are noted and used for the identification of organic substances. Archaeologically this can be useful for identifying sources, as for amber. There are several methods of chromatography, but particularly used in archaeology are paper and gas. In the former, a solution of the substance to be examined is placed at the end of a piece of filter paper; the end is then dipped into a solvent which moves the constituents of the sample along the paper by capillary action. Different substances reach different points on the filter paper and, by comparison with reference substances, can be identified. Gas chromatography is done by introducing the mixture into a column of material. The mixture is carried through by gases and measurements of the gas coming through over time are made by a gas detector. The use of gas chromatography in the study of amber has shown that different sources produce different chromatograms.
Clyde-Carlingford tombs: CATEGORY: site
DEFINITION: A series of megalithic chamber tombs in southwestern Scotland and northern Ireland with some radiocarbon dates before 3000 BC, an early stage of the Neolithic. They are sometimes described as segmented gallery graves, since they have subdivided rectangular chambers. Another important characteristic was a concave or semicircular forecourt. In some of the Irish examples, this was oval or circular and they are described as court cairns. The overlying cairns are long and either oval, rectangular, or trapezoidal in shape. Collective inhumation was the normal practice, although cremation sometimes occurred in Ireland.
colorant: CATEGORY: artifact
DEFINITION: A chemical element that contributes color to a mixture; unglazed, low-fired pottery is colored chiefly by carbon, iron, and manganese, whereas a broader range of colors occurs in glazes
consolidation: CATEGORY: term
DEFINITION: The use of resin or other chemical after dehydration of bone to strengthen it for conservation.
coprolite: CATEGORY: artifact; fauna
DEFINITION: Fossilized or desiccated human or animal feces. The study of these remains can provide information about the human or animal activity in that particular locale, such as diet and disease; the study of these remains is called coprology. Coprolites only survive in exceptional circumstances -- arid, frozen, and occasionally waterlogged deposits. They can be reconstituted by the addition of chemicals like trisodium phosphate, and can then be analyzed for their plant and animal remains. This gives additional insight into what was being eaten on a site, since the evidence from pollen analysis, or flotation, only suggests what was being grown.
court cairn: SYNONYM: Clyde-Carlingford tomb
CATEGORY: structure
DEFINITION: A type of Neolithic (c 3500 BC) chamber tomb common in southwest Scotland and northern Ireland. Its features include an elongated rectangular or trapeze-shaped cairn with an unroofed semicircular forecourt at one end. The courtyard gives access to the burial chamber proper, which is normally a gallery with two or more chambers separated by jambs, or by a combination of jambs and sills. This basic form sometimes called a 'horned cairn' has many variants. In the 'lobster-claw' or 'full court', cairns the wings of the facade curve around until they almost meet at the front of the tomb to enclose a circular or oval forecourt. Sometimes a cairn contains more than one tomb or there are subsidiary chambers. Court cairns continued to be used until the end of the Neolithic period around 2200 BC. The later court cairns share many features with the Severn-Cotswold tombs of southwest Britain and with the transepted gallery graves near the river Loire.
cromlech: SYNONYM: dolmen
CATEGORY: structure
DEFINITION: A term used in Wales for any Megalithic tomb. In Britain, the term refers to a circle of upright stone of prehistoric times. The enclosure was formed by menhirs, huge stones planted in the ground in a circle or semicircle. These enclosures were consecrated places used as burial grounds. The former usage is now obsolete in archaeological literature but has persisted in Welsh folk usage.
depletion gilding: CATEGORY: geology
DEFINITION: A New World metallurgical technique in which tumbaga (copper and gold alloy) metal artifacts wee treated with chemicals that removed much of the copper from the surface, leaving a finish that looks like pure gold.
deposition: SYNONYM: depositional process
CATEGORY: geology; term
DEFINITION: Any of the various processes by which artifacts move from active use to an archaeological context, such as loss, disposal, abandonment, burial, etc. It is the laying, placing, or throwing down of any material. In geology, it is the constructive process of accumulation into beds, veins, or irregular masses of any kind of loose, solid rock material by any kind of natural agent (wind, water, ice). The transformation of materials from a systemic to an archaeological context are directly responsible for the accumulation of archaeological sites and they constitute the dominant factor in forming the archaeological record. Deposition is the last stage of behavioral processes, in which artifacts are discarded.
desert varnish: CATEGORY: geography
DEFINITION: A chemical dark-colored crust or film of iron and manganese oxides (usually with some silica) that is deposited on exposed rocks, artifacts, and petroglyph surfaces. Of bacterial origin, this varnish becomes polished by wind abrasion can be used in cation ratio dating; its organic matter can be analyzed by accelerator mass spectrometer radiocarbon dating.
differential heat analysis: SYNONYM: differential thermal analysis
CATEGORY: technique
DEFINITION: A remote sensing technique in which the variability in heat absorption and dissemination is used to plot hidden archaeological features. In analytical chemistry, this technique is used for identifying and quantitatively analyzing the chemical composition of substances by observing the thermal behavior of a sample as it is heated.
electrolysis: CATEGORY: technique
DEFINITION: A cleaning technique used in archaeological conservation. Artifacts are placed in a chemical solution, and by passing a weak current between them and a surrounding metal grill, the corrosive salts move from the cathode (object) to the anode (grill), removing any accumulated deposit and leaving the artifact clean. The process of electrolysis works by passing an electric current through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron (oxidation or reduction).
electron probe microanalysis: SYNONYM: electron probe microanalyzer
CATEGORY: technique
DEFINITION: A physical method of chemical analysis which can determine the constituent elements in metal, stone, glass, pigments/stains, and pottery/ceramics. The technique is slightly destructive, requiring the removal of a small sample from the artifact. An electron beam is used to excite the atomic electrons and the result is the emission of secondary X-rays with characteristic wavelengths for the elements concerned. The beam can be focused on to a very small area of the specimen, and can be moved around to sample different points: thus the method is particularly useful for the study of surface enrichment in metals and of pigments. It can be used with samples as small as 10 -11 cubic centimeter and is similar to XRF (X-ray fluorescence spectrometry).
environment: CATEGORY: term
DEFINITION: The complex of physical, chemical, and biological factors that act upon an organism or an ecological community and ultimately determine its form and survival. The pace of environmental change quickened dramatically with the introduction of agriculture from 7000 years ago onwards: forests were cut down and cultivation led to soil degradation and erosion. New species were introduced, both as crops and weeds, and the relentless growth of population ensured that man's activities made an ever-increasing impact on the landscape.
erosion: SYNONYM: weathering
CATEGORY: geology
DEFINITION: The wearing away or loosening and transportation of soil or rock by water, wind, and ice. A group of processes are involved in the physical breakdown or chemical solution, removal, and transportation of the materials. Erosion can be accelerated by activities on the landscape. Three forms that can have significant impact on the archaeological record are soil erosion, gully erosion, and wind erosion.
ethnology: SYNONYM: cultural anthropology
CATEGORY: related field
DEFINITION: The use of ethnographic data to study contemporary cultures; one of the four subdisciplines of cultural anthropology. The study of the varieties of the human race in a comparative analysis to understand how they work and why they change. Ethnology is a term more widely used in Europe, and encompasses the analytical and comparative study of cultures in general, which in American usage is the academic field known as cultural anthropology (in British usage, social anthropology).
fireplace: SYNONYM: fire-place, hearth
CATEGORY: structure
DEFINITION: A place for building a fire, especially a semiopen space with a chimney; housing for an open fire within a dwelling. They are used for heating and cooking. Very early medieval fireplaces had semicircular backs and hoods and there was no chimney; the smoke passed out through an opening in the wall. By the 11th century, chimneys were added. Early fireplaces were made of stone; later, brick became the more popular material.
firing: CATEGORY: ceramics
DEFINITION: The process of heating raw ceramics to a high temperature, driving all the water out of the paste and (depending on the composition of the paste and tempering) causing new chemical bonds to form within the paste.
flake scatter: CATEGORY: lithics
DEFINITION: A quantity of stone flakes loosely discarded during toolmaking, often found in a semicircle pattern where work was done.
flint: SYNONYM: chert, firestone
CATEGORY: geology
DEFINITION: A type of hard stone, often gray in color, found in rounded nodules and usually covered with a white incrustation. A member of the chalcedony group of water-bearing silica minerals, it was found from early use to fracture conchoidally and was ideal for making stone tools with sharp edges. It is chemically a quartz, but has a different microcrystalline structure. It can therefore be flaked readily in any direction and so shaped to many useful forms. It occurs widely, and where available was the basic material for man's tools until the advent of metal; it is commonest 'stone' of the Stone Age. The only types of stone preferred to it were obsidian and the tougher rocks used for ground tools in the Neolithic. The term is often used interchangeably with chert and also as a generic term denoting stone tools in the Old World. Nodules of flint occur commonly as seams in the upper and middle chalk of northwest Europe. During the Neolithic and Copper Age of Europe, flint workers recognized that flint from beds below ground were of superior quality to surface flint, especially for the manufacture of large tools such as axes. These beds were exploited by sinking shafts and then excavating galleries outwards. Flint mines are known from many areas of Europe and good examples occur in Poland (Krzemionki), Holland, Belgium (Spiennes) and England (Grimes Graves).
fluorine dating: SYNONYM: fluorine test
CATEGORY: technique
DEFINITION: A relative dating technique used on bone. Bone absorbs fluorine from groundwater at a rate proportional to the time since burial -- if groundwater migration rates remain constant. Fluorine concentrations are chemically analyzed by the gradual combination of fluorine in groundwater with the calcium phosphate of the buried bone material. Bones from the same stratigraphical context can be dated relatively by comparison of their fluorine content. The Piltdown forgery was finally exposed by this method.
Fontbouïsse: CATEGORY: site; artifact
DEFINITION: A Chalcolithic (Copper Age) settlement site in Gard, France, which has given its name to a style of pottery decorated with channeled decoration arranged usually in metopic or concentric semicircle patterns. Fontbouïsse ware is widespread in southern France, occurring in chamber bombs, village sites, burial caves, natural rock clefts, and small cremation cysts. It is also the name of a cultural group known for its dry-stone houses, megalithic tombs and caves used for burials, and is associated with extensive flint mining and the first evidence of copper working in the area.
formation process: SYNONYM: site formation process
CATEGORY: term; technique
DEFINITION: The total of the processes -- natural and cultural, individual and combined -- that affected the formation and development of the archaeological record. Natural formation processes refer to natural or environmental events which govern the burial and survival of the archaeological record. Cultural formation processes include the deliberate or accidental activities of humans. On a settlement site, for example, the nature of human occupation, the activities carried out, the pattern of breakage and loss of material, rubbish disposal, rebuilding, or re-use of the same area will all influence the surviving archaeological deposits. After the site's abandonment, it will be further affected by such factors as erosion, glaciation, later agriculture, the activities of plants and animals, as well as the natural processes of chemical action in the soil. Reconstruction of these processes helps to relate the observed evidence of an archaeological site to the human activity responsible for it.
geology: CATEGORY: geology; related field
DEFINITION: The study of the physical, chemical, and biological processes and products of the earth; simply, the study of the history of the earth and an understanding of the time scale over which man developed. Geology's aims overlap considerably with those of archaeology, particularly in the prehistoric periods. For example, work on the stratigraphy of the Quaternary to provide a geological chronology for the study of the reconstruction of environmental changes throughout the Quaternary forms an essential background to all archaeology. The palaeontology of fossil hominids and the other animals that lived at the same time is another area in which geology and archaeology overlap. The geological methods of dating such as radiocarbon, palaeomagnetism, and potassium-argon form the basis of most prehistoric chronologies. Geophysical techniques are used for the location of sites and petrology traces the origins of stone implements and inclusions in pottery.
gold: CATEGORY: geology
DEFINITION: A chemical element; a dense, lustrous, yellow precious metal with several qualities that have made it exceptionally valuable throughout history. It is attractive in color and brightness, durable to the point of virtual indestructibility, highly malleable, and usually found in nature in a comparatively pure form. It was one of the first metals to be exploited by man. Early working was basically by hammering, to which more complicated techniques like casting, soldering, granulation, and filigree were later added.
hippodrome: SYNONYM: hippodromus; (Roman circus)
CATEGORY: structure
DEFINITION: An ancient Greek stadium for horse and chariot racing. The typical hippodrome was dug into a hillside and an embankment was created for supporting seats on the opposite side. The hippodrome was oblong, with one end semicircular and the other square (resembling a U with a closed top). There were tiered seats along the length and curve; at the straight end dignitaries occupied seats. A low wall (spina) ran most of the length of the stadium and divided the course. The spina was decorated with monuments and had sculptures that could be tilted or removed to keep spectators informed of the laps completed by the racers. It is much the same as a stadium, but intended rather for horse- than foot-racing. The hippodrome was the initial model for the Roman circus, which likewise concentrated on chariot-races.
huang: CATEGORY: artifact
DEFINITION: A flat semicircular or arc-shaped jade pendant known from Neolithic sites in China and made throughout the Bronze Age.
infrared absorption spectrometry: SYNONYM: infra-red absorption spectrometry
CATEGORY: technique
DEFINITION: A technique used to identify mineral and chemical composition artifacts, either to determine their nature or for identification of their source. A small sample is taken from the object and is ground finely before being subjected to infrared radiation. Constituent atoms in the specimen vibrate at characteristic frequencies; if the frequency is the same as that of the radiation, the radiation will be absorbed, while if frequencies do not match, the radiation will pass through the sample. A measurement of the amount of absorption at each wavelength leads to the identification of the minerals and chemical compounds present. Though the method can be used for both inorganic and organic materials, it tends to be used alongside X-ray diffraction for inorganic substances, where it is more sensitive to poorly crystallized minerals. It is most useful for organic materials such as amber, as the organic compounds in the amber absorb different wavelengths of infrared radiation passed through them.
intrinsic attribute: CATEGORY: typology
DEFINITION: A characteristic that is inherent in an object, such as its length or mass or chemical composition.
isotope: CATEGORY: geology
DEFINITION: Atoms of the same element that have different atomic masses due to having different numbers of neutrons in the nuclei, but which still have similar chemical properties. Many of these forms of elements with a specific number of electrons (such as carbon 14 or potassium 40) are unstable and decay into different elements, releasing their surplus electrons. Radiocarbon, potassium-argon, fission track, and thermoluminescence dating all rely on this phenomenon in different ways.
isotopic analysis: CATEGORY: technique
DEFINITION: Any dating technique relying on the phenomenon of isotopal decay -- analyzing the ratios of the principal isotopes. The analysis of isotopes -- any of two or more species of atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties
isotopic fractionation: CATEGORY: technique
DEFINITION: The enrichment of one isotope relative to another in a chemical or physical process. Two isotopes of an element are different in weight but not in gross chemical properties, which are determined by the number of electrons. It can be predicted theoretically and demonstrated experimentally, however, that subtle chemical effects do result from the difference in mass of isotopes. Isotopes of an element may have slightly different equilibrium constants for a particular chemical reaction, so that fractionation of the isotopes results from that reaction. One of the assumptions of radiocarbon dating is that Carbon 12, Carbon 13, and Carbon 14 are passed around the carbon cycle at similar rates. The three isotopes are chemically very similar, but slight differences between them may cause them to be taken up at different rates by some plants and animals. This isotopic fractionation may cause inaccuracies in radiocarbon dating. Both Carbon 12 and Carbon 13 are stable isotopes and their ratio should therefore remain constant throughout life and after death. If it has changed from the expected value, then fractionation has occurred. Once the degree of fractionation is known, it can be corrected for mathematically by the laboratory.
isotopic replacement: CATEGORY: technique
DEFINITION: A chemical process which creates inaccuracies in radiocarbon/radiometric dating. An isotope within a sample is exchanged with an isotope of the same element that is a different age. This can occur in fossil shells whose C14 isotope in the calcium carbonate may be replaced during recrystallization by different carbon isotopes dissolved in the surrounding groundwater.
karst: CATEGORY: geology
DEFINITION: An irregular limestone region with sinkholes, underground streams, and caverns. Karsts owe their existence to the removal of bedrock in solution and to the development of underground drainage without the development of surface stream valleys. Karst is characterized by the formation and growth of cavities resulting from chemical weathering and erosion in regions of carbonate and evaporite rocks. Karsts show much variation and are usually described in terms of a dominant landform. Most important are fluviokarst, doline karst, cone and tower karst, and pavement karst. Approximately 15 percent of the Earth's land surface is karst. The most extensive karst area of the United States occurs in the limestones of Mississippian age (about 325,000,000-345,000,000 years old) of the Interior Low Plateaus. Karst also occurs in the limestones of Ordovician age (about 430,000,000-500,000,000 years old) in Kentucky and Tennessee.
Lyell, Sir Charles (1797-1875): CATEGORY: person
DEFINITION: Scottish geologist largely responsible for the general acceptance of the view that all features of the Earth's surface are produced by physical, chemical, and biological processes over long periods of geological time (uniformitarianism). Lyell's achievements laid the foundations for evolutionary biology as well as for an understanding of the Earth's development. His work had a bearing on the development of archaeology at two points. His Principles of Geology" (1830-1833) established the view that the earth had been in existence for very much longer than the 6000 years allowed by the biblical chronology and laid open the way for the later acceptance of the antiquity of man. In 1859 publication of Darwin's "Origin of Species" gave new impetus to Lyell's work. Lyell's "The Geological Evidence of the Antiquity of Man" (1863) tentatively accepted evolution by natural selection."
Mössbauer spectroscopy: CATEGORY: technique
DEFINITION: A technique used in the analysis of artifact composition, particularly iron-bearing minerals in pottery. It involves the measurement of the gamma radiation absorbed by the iron nuclei, which provides information on the particular iron compounds in the sample, and hence on the conditions of firing when the pottery was being made. Samples are bombarded with gamma rays and a record made of the detected amount of absorption by iron nuclei. The use of this method of physical analysis has been confined mainly to the examination of iron compounds, though other uses have been suggested. The Mössbauer effect of recoil-free emission and absorption of gamma rays only occurs with a limited number of isotopes, of which one of the iron isotopes is useful in archaeological contexts. Because of its sensitivity to short-range crystalline order, the technique is better for examining poorly crystallized iron-bearing minerals than X-ray diffraction. This type of spectroscopy is also used for the study of nuclear hyperfine structure, chemical shifts, and chemical analysis.
Malthus, Thomas Robert (1766-1834): CATEGORY: person
DEFINITION: English economist and demographer, best known for his theory that population growth overrun available food resources unless it is controlled by catastrophes such as war, epidemics, or natural disasters -- or with limits on reproduction.
metallurgical analysis: CATEGORY: technique
DEFINITION: The study of metals. Metal artifacts and the tools or waste products of their manufacture are examined to reconstruct manufacturing processes, the source of raw materials, and the usage. This may be done by the various techniques of chemical analysis, or may involve metallographic examination under a microscope. In the case of copper, bronze, and other non-ferrous metals, such analysis may yield information about alloys, casting, cold-working, and annealing. For iron and steel, there may be information about forging, carburization, quenching, and tempering.
mineral: CATEGORY: geology
DEFINITION: A solid homogeneous crystalline chemical element or compound that results from the inorganic processes of nature. The term includes any of various ground substances such as stone, coal, salt, sulfur, sand, petroleum, water, or natural gas. Each of these naturally occurring substances has a characteristic chemical composition expressed by a chemical formula.
neutron activation analysis: SYNONYM: NAA
CATEGORY: technique
DEFINITION: A physical method of chemical analysis used to determine the composition of various substances such as flint, obsidian, pottery, coins, etc. found in archaeological contexts. It can be totally nondestructive to the sample and involves the excitation of the atomic nuclei rather than the atomic electrons. The specimen is bombarded with neutrons which interact with nuclei in the sample to form radioactive isotopes that emit gamma rays as they decay. The energy spectrum of the emitted rays is detected by a scintillation or semiconductor counter. Constituent elements and concentrations are identified by the characteristic energy spectrum of emitted rays and their intensity. The time between the neutron activation of the sample and the measurement of the gamma rays depends on the half-lives of the radioactive isotopes, which may range from seconds to thousands of years: often a few weeks may be necessary before measurement takes place. Neutron activation analysis has an advantage over X-ray fluorescence spectrometry since it analyzes the whole specimen as opposed to the surface only. Care must be taken that the neutron dose is not so great as to make the specimen radioactively unsafe for handling. The method is particularly useful for the identification of trace elements; however, it is not universally applicable since some elements have too short a half-life for measurement, and others do not form radioactive isotopes. The method is accurate to about plus or minus 5 percent. Neutron activation analysis of certain Hopewell artifacts made of obsidian has proven that the source of the obsidian was in what is now Yellowstone National Park.
nitrogen dating: SYNONYM: nitrogen test
CATEGORY: technique
DEFINITION: A relative dating technique used on bone, based on the gradual reduction of nitrogen in bone as collagen is broken down into amino acids and leached away. Bone collagen decomposes, releasing nitrogen, at a fairly uniform slow rate. Nitrogen is present in bone in a proportion of approximately 4 percent. The relative ages of bones in similar burial environments can be compared by looking at the remaining nitrogen content; it is relative since the rate of decline is affected by local environmental factors such as temperature or chemical constituents in the find deposit. Nitrogen concentrations are determined by chemical analysis.
notching: CATEGORY: lithics
DEFINITION: The practice of chipping small, semicircular notches out of the base or side of a projectile point in order to aid in hafting.
nymphaeum or nymphaion: SYNONYM: nympheum
CATEGORY: structure
DEFINITION: An ancient Greek and Roman sanctuary consecrated to water nymphs. It was an elaborately decorated public drinking fountain -- a semicircular monumental Classical fountain house. It often had niches filled with sculpture. The nymphs were associated with a range of natural features such as water, mountains, and trees. Nymphaea were often erected near the head of a spring. The nymphaeum served as a sanctuary, a reservoir, and an assembly chamber where weddings were held. The rotunda nymphaeum, common in the Roman period, was borrowed from such Hellenistic structures as the Great Nymphaeum of Ephesus. Nymphaea existed at Corinth, Antioch, and Constantinople; the remains of about 20 have been found in Rome; and others exist as ruins in Asia Minor, Syria, and North Africa. The word 'nymphaeum' was also used in ancient Rome to refer to a bordello and also to the fountain in the atrium of the Christian basilica.
obsidian: SYNONYM: hyalopsite, Iceland agate, mountain mahogany
CATEGORY: geology
DEFINITION: A jet-black to gray, naturally occurring volcanic glass, formed by rapid cooling of viscous lava. It was often used as raw material for the manufacture of stone tools and was very popular as a superior form of flint for flaking or as it is easily chipped to form extremely sharp edges. Obsidian breaks with a conchoidal fracture and is easily chipped into precise and delicate forms. It was very widely traded from the anciently exploited sources in Hungary, Sardinia, Lipari of Sicily, Melos in the Aegean, central and eastern Anatolia, Mexico, etc. Chemical analysis of their trace elements now allows most of the sources to be distinguished (especially by neutron activation and x-ray fluorescence spectrometry), so that the pattern of trade spreading out from each can be traced. Two dating methods have been applied to obsidian: obsidian hydration dating and fission track dating. In Europe, obsidian was exploited extensively from c 6000-3000 BC; after 3000 BC it generally went out of favor for everyday purposes (perhaps as a result of competition from metal tools) but it continued to be used for prestige objects in some areas, especially by the Minoans and Mycenaeans. Obsidian has been quarried and traded by western Melanesians since at least 19,000 bp, with the earliest-used and most important source being that at Talasea on New Britain. Obsidian was also an important trade item in Mesoamerica.
obsidian hydration dating: SYNONYM: obsidian hydration layer dating, obsidian dating
CATEGORY: technique
DEFINITION: A method of dating in which the age of an obsidian artifact is established by measuring the thickness of its hydration rim (layer of water penetration) and comparing that to a known local hydration rate. The hydration layer is caused by absorption of water on exposed surfaces of the rock. The surface of obsidian starts to absorb water as soon as it is exposed by flaking during manufacture of an artifact. The layer of hydrated obsidian is visible when a slice of the artifact is examined under an optical microscope at a magnification of x 500. Hydration varies geographically, and several factors such as climate, chemical environment, and physical abrasion also affect the thickness of the layer, so that most studies are locally or regionally based. Obsidian may also be dated by the fission track dating technique. Dates have been obtained in Japan extending back as far as c 25,000 BC.
Orange: SYNONYM: Roman Arausio
CATEGORY: site
DEFINITION: A colonia in southern France, established under Augustus' rule (27 BC-14 AD) which became a prosperous city. In the pre-Roman period, the area was occupied by rich, powerful Celtic tribes who appreciated its strategic position on the Rhône River. The semicircular theater, probably built during the reign of Augustus, is the best preserved of its kind. The tiered benches, which rise on the slopes of a slight hill, originally seated 1100. The magnificent wall at the back of the theater is 334 feet (102 m) long and 124 feet (38 m) high. An imposing statue of Augustus, about 12 feet (3.7 m) high, stands in the wall's central niche. Orange also has the Triumphal Arch of Tiberius (c 20 AD) that is one of the largest built by the Romans; standing c 61 feet (19 m) high, its sculptures show the victories of Julius Caesar. A lime kiln near the theater has produced fragments which document various local land surveys and, in particular, describe the terms of confiscation and redistribution that were applied at the time of the original founding of the colonia. In the 5th century, Arausio was pillaged by the Visigoths.
organic residue analysis: CATEGORY: technique
DEFINITION: Use of chemicals to extract and identify traces of plant and animal materials from pottery.
patina: SYNONYM: patination
CATEGORY: artifact; geology
DEFINITION: The outermost layer of an artifact, which may differ in color, texture, luster, or substance from the inner part of the artifact due to physical, biological, or chemical alteration due to environmental conditions. The term also refers to any thin, colored film or layer formed on the surface of flint or other rock as a result of alkaline conditions. It is a porous bluish or white weathering; possibly becoming stained with brown or yellow due to contacts with iron compounds in percolating water. Similarly, the green patina on bronze objects is a product of corrosion. The amount of patination is sometimes used as a very rough indication of age; the longer the exposure the deeper is the patination.
pedogenesis: CATEGORY: term
DEFINITION: The interaction of the physical, chemical, and biological factors, processes, and conditions that cause a soil to evolve into a soil horizon.
pedology: CATEGORY: related field
DEFINITION: The study of soils and their structure, especially the creation, characteristics, distribution, and uses of soils. Archaeology depends an identification of soils to come up with the proper interpretation of the context and integrity of deposits. This scientific discipline is concerned with all aspects of soils, including their physical and chemical properties, the role of organisms in soil production and in relation to soil character, the description and mapping of soil units, and the origin and formation of soils.
Pengelly, William (1812-1894): CATEGORY: person
DEFINITION: A British geologist and archaeologist who did cave excavation and demonstrated the antiquity of Palaeolithic artifacts by showing that stone tools made by humans were contemporary with remains of extinct animals. At Kent's Cavern, he was able to confirm the conclusions of Reverend J. MacEnery that flint tools were associated with the bones of extinct animals. Though this association was not widely accepted, he continued to find further proof with work at Windmill Cave, Brixham (Devon). He gained academic support and, in 1859, John Evans and several of Britain's leading geologists joined him in contradicting the 4004 BC date as the Creation of man. The discoveries of Jacques Boucher de Perthes in the Somme Valley in France corroborated Pengelly's findings and were used to demonstrate the antiquity of man in 1859, the same year that saw the publication of Darwin's revolutionary Origin of Species"."
plating: CATEGORY: artifact
DEFINITION: The coating a metal or other material such as plastic or china with a hard, nonporous metallic surface to improve durability and beauty. Gold, silver, stainless steel, palladium, copper, and nickel are formed by dipping an object into a solution containing the desired surface material, which is deposited by chemical or electrochemical action. While much plating is done for decorative purposes, still more is done to increase the durability and corrosion-resistance of softer materials.
platinum: CATEGORY: geology
DEFINITION: A very heavy, precious, silver-white metal that is soft and ductile and has a high melting point and good resistance to corrosion and chemical attack. It is found in the Transvaal, South Africa, among other places.
Pnyx or pnyx: CATEGORY: structure
DEFINITION: An ancient Greek open-air auditorium for public (popular) assemblies; the site in Athens (a hill to the west of the Acropolis) where the Ecclesiae were held. It was a semicircular rising ground, with an area of 12,000 square yards, leveled with a pavement of large stones, and surrounded by a wall, behind which was the bema or platform from which speakers addressed the people. It was used from the 6th century BC and remodeled in the 4th century BC.
polyvinyl acetate: CATEGORY: term
DEFINITION: A chemical mixture that may be brushed on bones to consolidate and protect them.
primary clay: CATEGORY: geology
DEFINITION: Any clay formed in place by the chemical and physical weathering of rock.
radioactive isotope: SYNONYM: radioisotope
CATEGORY: term
DEFINITION: Any of several species of the same chemical element, such as carbon, with different masses whose nuclei are unstable and dissipate excess energy by spontaneously emitting radiation in the form of alpha, beta, and gamma rays.
radiography: SYNONYM: x-radiography; also X-ray microscopy and microradiographic techniques
CATEGORY: technique
DEFINITION: The physical technique of producing a photographic image of an opaque specimen by transmitting a beam of X-rays through it onto an adjacent photographic film; the image results from variations in thickness, density, and chemical composition of the specimen. The technique is used to study details of structure, decoration, or composition invisible to the naked eye. X-rays are normally used, though gamma-rays may be employed in circumstances where an X-ray tube is difficult to manipulate. Differential absorption of the rays denotes variations in composition, and these are shown on the film as contrasting light and dark tones. This form of examination works well on iron objects where rust and corrosion products prevent proper study of the object. Radiography is also used in the study of biological material, such as bone and mummies. Radiography has also been used to examine sedimentary structures. Microradiographic techniques have been developed to examine the atomic structure of crystalline substances.
reclamation: SYNONYM: reclamation process
CATEGORY: term; technique
DEFINITION: Any of various processes by which artifacts move from an archaeological context to an active status, i.e. are reclaimed" as when a later society makes use of objects deposited earlier. It is the transition of cultural materials from the archaeological record back into the systemic context such as the scavenging of archaeological artifacts for reuse by both nonindustrial and industrial peoples. The act of archaeological excavation is actually reclamation."
reclamation process: CATEGORY: artifact
DEFINITION: The transition of cultural materials from the archaeological record back into the systemic context; archaeological excavation itself is reclamation
rock: CATEGORY: lithics
DEFINITION: An aggregate of one or more minerals that can be defined by both physical properties and mineral content. The three forms are igneous, rock that has cooled from a molten state; sedimentary, rock that has formed through the accretion of sediments; and metamorphic, rock formed from preexisting rocks subjected to extreme heat, pressure, or chemical change.
scanning electron microscopy: SYNONYM: SEM
CATEGORY: technique
DEFINITION: A technique used to gain information on the microscopic and submicroscopic structure of a wide range of materials ceramics, metals, stone, teeth, hair etc. It involves a type of electron microscope (SEM) in which a beam of electrons systematically sweeps over the specimen, the electron beam passing through a series of magnetic lenses which demagnify the beam diameter. The backscattered electrons and secondary electrons emitted are detected by means of a scintillation or semiconductor counter. The angle at which the beam hits the surface of the specimen determines the number of backscattered and secondary electrons detected, and thus the pattern of contrast represents the topography and elements of the specimen. The signal from these emissions is processed and an image of the object is displayed on a screen. Its advantages over transmission electron microscopy include a greater depth of focus at high magnification and its ability to deal with specimens of much greater bulk, making it less destructive. The chemical composition of the material of the surface can also be deduced from the backscattered electrons. No elaborate specimen-preparation techniques are required for examination in the scanning electron microscope, and large and bulky specimens may be accommodated.
sedimentology: CATEGORY: related field
DEFINITION: A subdivision of geomorphology concerned with the investigation of the structure and texture of sediments, i.e. the global term for material deposited on the earth's surface. This scientific discipline is concerned with the physical and chemical properties of sedimentary rocks and the processes involved in their formation, including the transportation, deposition, and lithification (transformation to rock) of sediments.
site-formation processes: SYNONYM: site formation process; formation process
CATEGORY: term
DEFINITION: The total of the processes -- natural and cultural, individual and combined -- that affected the formation and development of the archaeological record. Natural formation processes refer to natural or environmental events which govern the burial and survival of the archaeological record. Cultural formation processes include the deliberate or accidental activities of humans. On a settlement site, for example, the nature of human occupation, the activities carried out, the pattern of breakage and loss of material, rubbish disposal, rebuilding, or re-use of the same area will all influence the surviving archaeological deposits. After the site's abandonment, it will be further affected by such factors as erosion, glaciation, later agriculture, the activities of plants and animals, as well as the natural processes of chemical action in the soil. Reconstruction of these processes helps to relate the observed evidence of an archaeological site to the human activity responsible for it.
skeuomorph: SYNONYM: adj. skeuomorphic
CATEGORY: artifact
DEFINITION: An object in which its shape or decoration copies the form it had been when made from another material or by another technique. For example, a pot would be decorated to make it look similar to a vessel of basketry, skin, or other material. In some cases, it is an artifact which represents in decorative form a feature which was originally functional. A decorative bow attached to a shoe is a skeuomorph of the laces once used to tie it; triangular shapes drawn below handles on pottery are skeuomorphs of the metal plates by which the handles on metal prototypes were attached; and the semicircular mark on the back of a teaspoon represents the broadening of the handle where it was soldered to the bowl when it used to be made in two pieces. Frequently a skeuomorph may yield important information about extinct types, especially when organic materials like basketry are recorded in this way.
smelting: SYNONYM: smelt
CATEGORY: geology
DEFINITION: The separation of metal from ore, usually by heating in a hearth or furnace. It is a major process in metalworking, producing the usable metal for the making of artifacts. After smelting, copper can be cast and iron can be forged. The main chemical reaction in smelting most of the ores used in antiquity is that of reducing a metal oxide. If the ore was not already in the oxide form, then it was converted by a preliminary process. Careful control of the amount of air entering the furnace would be required for successful smelting. Remains of the smelting process include ingots, slag, tuyères, hearths containing slag and cinder, and more sophisticated furnaces.
Smithfield: CATEGORY: culture
DEFINITION: A Later Stone Age industry and hunting and gathering culture of southern Africa, originally thought contemporary with the Wilton, but technologically different from it, and now referring to a complex between 1300-1700 AD. The culture was on the same level as that of the Mesolithic people of Europe or the modern Kalahari bushmen. The unifying feature of this industry was the almost complete absence of backed microliths and tiny semicircular scrapers.
soil analysis: SYNONYM: pedology
CATEGORY: technique
DEFINITION: The study of soil and subsoil to determine climate, vegetation, and human disturbance. It is used to assist the interpretation of deposits. Tools are primarily mechanical grading of particle size, determination of soil color, chemical tests like phosphate analysis, and pollen analysis.
soil chemistry: CATEGORY: related field
DEFINITION: Methods used to analyze the chemical composition of soils to determine if there was human settlement.
soil horizon: CATEGORY: geology
DEFINITION: A layer in a soil developed through the natural weathering of geological and archaeological surfaces. It differs from related layers chemically, physically, or biologically. Sequences of related soil horizons make up the soil profile.
soil profile: CATEGORY: feature; geology
DEFINITION: The vertical sequence of horizons in the soil which occur not as the result of stratification but as a result of weathering and other processes. The profile provides environmental or palaeoenvironmental information, such as information on vegetation and climate. The term also refers to a vertical section exposed in excavation or naturally that shows horizons and parent material. The soil profile is made up of some or all of the following: the A or humus horizon, the E or leached horizon, the B or (B) horizons or accumulation or chemical weathering, and the C horizon of parent material. Different soil profiles occur in different environmental regions, ranging from rendsinas, through brown earths, to podsols, gleys, and chernozems. The soil profile and the type of vegetation are interdependent, and man's activities have an effect on and are affected by both.
specific gravity determination: SYNONYM: relative density
CATEGORY: technique
DEFINITION: Specific gravity is the ratio of the density of a substance to the density of pure water taken as a standard when both densities are obtained by weighing in air and in prescribed temperature conditions. The measurement of the specific gravity of a metal artifact can be a useful non-destructive method of determining its composition, if it is a two-component alloy and preferably if one of the alloy components is known. The specimen must be weighed in the air and then suspended in a suitable liquid with a known specific gravity; the result is determined by an equation. Since the presence of a third metal in small amounts upsets the accuracy of the technique, the amount of fore-knowledge required is greater than in most of the other methods of determining the chemical composition of objects. Devices used to measure specific gravity are the Jolly balance, the Westphal balance, the pycnometer, and the hydrometer.
spokeshave: CATEGORY: lithics
DEFINITION: A stone tool with a semicircular concavity used for smoothing spears or arrowshafts; a drawknife or small transverse plane with end handles for planing convex or concave surfaces
stirrup spout: SYNONYM: stirrup-spout vessel
CATEGORY: artifact
DEFINITION: Semicircular tub set vertically, like a croquet hoop, on top of a closed vessel -- common in many Peruvian cultures (Moche, Chimu, Chavín, Cupisnique, Nazca) and other parts of the New World. The lower ends open into the body of the pot, and from the apex of the curve rises a single vertical spout. From the side, it looked like a stirrup. It had precursors in the Initial Period. In Chavín pottery; for example, the earliest stirrup spouts were relatively small, very thick and heavy, and the spout had a thick flange. As time went on, the stirrups became lighter and the spouts longer; the flange was reduced and finally disappeared. The necks of the flasks underwent similar changes. The Cupisnique stirrup-spouted vessels, some of which were modeled in the form of human beings, animals, or fruits, were the beginning of a north-coast tradition of naturalistic modeling.
Sumerian question: CATEGORY: term; language
DEFINITION: Academic question of the origins of the Sumerians, culturally and linguistically. Their language has no known relatives and is poorly understood, despite many cuneiform texts found in southern Mesopotamia. Sumerian is the oldest written language in existence.
tephrochronology: SYNONYM: tephrachronology
CATEGORY: technique
DEFINITION: A method for the relative dating of horizons in volcanic regions by identification of different layers of ash (tephra). Tephra layers (beds) are ideal stratigraphic markers because they are deposited instantaneously. Also, the chemical content of tephra (volcanic ash) is unique for each eruption. If artifacts lie below tephra known to have come from a certain eruption, the artifacts predate the eruption. Tephra layers may be dated by potassium-argon dating and fission track dating and they can sometimes be tied in to absolute chronology where radiocarbon dates can be obtained from material contemporary with the deposit. To establish a chronology it is necessary to identify and correlate as many tephra units as possible over the widest possible area. In the Mediterranean, deep-sea coring produced evidence for the ash fall from the eruption of Thera, and its stratigraphic position provided important information in the construction of a relative chronology. The identification of multiple tephra beds may give bracketing ages for intervening strata. Tephrochronology has also been used to date glacial advances, sea level changes, and alluvial fans.
theater: SYNONYM: theatre
CATEGORY: structure
DEFINITION: Building or space in which a performance is given to an audience, an important adjunct of most Greek and Roman towns. In ancient Greece, where theatre began in the 5th century BC, the theatres of the classical period were constructed between two hills (essentially D-shaped) so that the audience sat in a tiered semicircular arrangement facing the orchestra circle, in which most of the action took place. (The name amphitheater should be used only of a circular or oval structure in which the seating completely surrounds the stage, as in the Colosseum). Greek theater consisted of two main elements: the orchestra, a space for acting and dancing which was usually circular; and the auditorium, a spectators' area, which was probably no more than a hillside or slope originally. Later, the skene (originally perhaps only a temporary structure for the convenience of performers) was added. Well-preserved examples survive at Epidaurus, Pompeii, and Orange.
Thomsen, Christian Jurgensen (1788-1865): CATEGORY: person
DEFINITION: Danish antiquary and first curator of the National Museum of Denmark. His main contribution to prehistory was the Three Age system (Stone, Bronze and Iron Ages), first devised in 1819 as a method of classifying the museum collections, but soon recognized as a tool of enormous value in interpreting the prehistoric past. He is considered the first ethnoarchaeologist and also promoted osteological studies and the chemical analysis of pot residue.
torus molding: CATEGORY: structure
DEFINITION: A semicircular or cylindrical band that forms the edge of a stela or the corner of a stone wall; a large convex molding usually semicircular in cross-section, especially at the base of a column. Some are decorated with a pattern that suggests lashings around a pole or reed bundle.
trace element: SYNONYM: accessory element, guest element
CATEGORY: geology
DEFINITION: Elements present in a mineral in minor proportions (between 0.1-2.0%) but which are frequently characteristic of the original source of the material. Trace elements occur naturally in minerals in soils and sediment and are not added deliberately to a substance. Minute amounts of chemical elements found in minerals emit characteristic wavelengths of light when heated to incandescence. Quantitative analyses of metal, clay, obsidian, etc. can show the amounts of the trace elements present and may suggest a source. Source identification can lead to further interpretations of trade and economic systems.
trace element analysis: CATEGORY: technique
DEFINITION: The use of quantitative chemical techniques, such as neutron activation analysis or X-ray fluorescence spectrometry, for determining the elements present in a mineral in minor proportions. These methods are widely used in the identification of raw material sources for metal, clay, obsidian, etc. Trace elements emit characteristic wavelengths of light when heated to incandescence.
uranium test: CATEGORY: technique
DEFINITION: A relative dating method used for bone. Calcium ions in the phosphatic mineral hydroxyapatite are gradually altered after burial into uranium ions as a result of uranium being in solution in the percolating groundwater. The longer bone has been in the ground, the more uranium will have been absorbed. The local environmental conditions affect the rate and therefore there is no universal rate which yields absolute dates. The uranium is radioactive and the emitted beta particles are measured using a Geiger counter. The method is much less destructive than the chemical analyses required for the nitrogen and fluorine tests.
vault: CATEGORY: structure
DEFINITION: A type of roofing in stone or brick using the principle of gravity to lock the materials together. The barrel vault is continuous and of semicircular section; in the rib vault, the weight of the roof is carried by ribs. The evolution of the vault begins with the discovery of the arch, because the basic barrel" form which appeared first in ancient Egypt and the Near East is simply a deep or three-dimensional arch."
WHMIS: SYNONYM: Workplace Hazardous Materials Information System
CATEGORY: geology
DEFINITION: A specification of health hazards involving laboratory chemicals, safety precautions, cleanup procedures, and treatments for burns or poisoning.
X-ray diffraction analysis: SYNONYM: x-ray diffraction analysis
CATEGORY: technique
DEFINITION: A technique used to identify minerals present in an artifact's raw materials; it can also be used in geomorphologic contexts to identify particular clay minerals in sediments and thus the source from which the sediment was derived. The technique identifies the major chemical components of an artifact, mainly on pottery though stone and weathering products on metal have also been analyzed. A sample is powdered and then bombarded with X-rays and a diffraction pattern is reflected onto and recorded as a series of arcs by photographic film. The patterns are compared with reference standards to identify the minerals present; mineral identification is based on the spacing between the arcs. X-ray diffraction can yield information on the manufacturing processes of pottery and metal and for this purpose the back-reflection diffraction method is used, which is totally non-destructive.
X-ray fluorescence: SYNONYM: X-ray fluorescence spectrometry, X-ray fluorimetry; XRF; X-ray fluorescence analysis
CATEGORY: technique
DEFINITION: A nondestructive physical method used for chemical analyses of solids and liquids. The specimen is irradiated by an intense X-ray beam and the lines in the spectrum of the resulting X-ray fluorescence are diffracted at various angles by a crystal with known lattice spacing; the elements in the specimen are identified by the wavelengths of their spectral lines, and their concentrations are determined by the intensities of these lines. Constituent elements are identified based on the unique wavelengths of fluorescent X-rays they emit and concentrations are estimated on the intensity of the released X-rays. It can be used on pottery, obsidian, glass, and some metal and under most circumstances is totally non-destructive. In general terms the method is more suitable for the analysis of the major elements in a specimen, though trace elements can be determined in some cases. Since automation of recording and sample changing is possible, large numbers of samples can be analyzed at speed, which gives this method a definite advantage over atomic absorption spectrometry and optical emission spectrometry.
Yeavering: CATEGORY: site
DEFINITION: Royal seat of the Anglo-Saxon Northumbria, England, in the 7th century AD and site of an impressive group of buildings. Great timber halls and a semicircular timber grandstand for meetings and assemblies have been excavated. Of the smaller buildings uncovered, one is thought to have been converted from a pagan temple into a church. It has advanced our knowledge of Saxon timber architecture.

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