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F-U-N dating
SYNONYMS OR RELATED TERMS: F.U.N. dating, F-U-N method
CATEGORY: technique
DEFINITION: A collective term for the techniques of fluorine, uranium, and nitrogen dating. It is a relative dating technique which compares concentrations of fluorine, uranium, or nitrogen in various samples from the same matrix to determine contemporaneity.
K-Ar dating
CATEGORY: technique
DEFINITION: Absolute dating technique that traces the transformation of one isotope into another - potassium (K) into argon (Ar). Its range is 100,000 years to 1.3 billion years.
absolute dating
SYNONYMS OR RELATED TERMS: 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.
amino acid dating
SYNONYMS OR RELATED TERMS: amino-acid dating; aminostratigraphy; amino-acid racemization, amino acid racemization
CATEGORY: technique
DEFINITION: A method of absolute (chronometric) dating which is hoped to fill the gap between radiocarbon dates and potassium-argon dates. It is used for human and animal bone and other organic material. Specific changes in its amino acid structure (racemization or epimerization) which occur at a slow, relatively uniform rate, are measured after the organism's death. The basis for the technique is the fact that almost all amino acids change from optically active to optically passive compounds (racemize) over a period of time. Aspartic acid is the compound most often used because it has a half-life of 15,000-20,000 years and allows dates from 5,000-100,000 years to be calculated. However, racemization is very much affected by environmental factors such as temperature change. If there has been significant change in the temperature during the time in which the object is buried, the result is flawed. Other problems of contamination have occurred, so the technique is not fully established. It is fairly reliable for deep-sea sediments as the temperature is generally more stable.
archaeomagnetic dating
SYNONYMS OR RELATED TERMS: archaeomagnetic intensity dating, archaeomagnetism, palaeointensity dating, archaeomagnetic age determination
CATEGORY: technique
DEFINITION: A chronometric method used to date objects containing magnetic materials - especially for buried undisturbed features such as pottery kilns, earthen fireplaces, and brick walls - which can be compared to known schedules of past magnetic alignments within a region and fluctuations in the earth's magnetic field. Clay and rocks contain magnetic minerals and when heated above a certain temperature, the magnetism is destroyed. Upon cooling, the magnetism returns, taking on the direction and strength of the magnetic field in which the object is lying. Therefore, pottery which is baked in effect fossilizes the Earth's magnetic field as it was the moment of their last cooling (their archaeomagnetism or remanent magnetism). In areas where variations in the Earth's magnetic field are known it is possible to date a pottery sample on a curve. This method yields an absolute date within about 50 years.
argon-argon dating
CATEGORY: chronology
DEFINITION: A high-precision method for estimating the relative quantities of argon-39 to argon-40 gas, used to date volcanic ashes between 500,000 and several million years old
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.
calibrated C-14 dating
CATEGORY: technique
DEFINITION: Dating through the use of the carbon-14 method by means of instrumentation having undergone extensive refinement primarily through calibration by dendrochronology.
carbon-14 dating
SYNONYMS OR RELATED TERMS: radiocarbon dating
CATEGORY: technique
DEFINITION: The occurrence of natural radioactive carbon in the atmosphere allows archaeologists the ability to date organic materials as old as 50,000 years. Carbon-14 is continuously produced in the atmosphere and decays with a half-life of 5,730-year (+/- 40 years). Unlike most isotopic dating methods, the carbon-14 dating technique relies on the progressive decay or disappearance of the radioactive parent with time. This is now a common method for estimating the age of a carbonaceous archaeological artifacts. The radioactivity of an artifact's carbon-14 content determines how long ago the specimen was separated from equilibrium with the atmosphere-plant-animal cycle. The method is based on the principle that all plants and animals, while they are alive, take in small amounts of carbon-14 and when they die, the intake ends. By measuring the loss rate of the carbon 14, the age of the object can be established. Measurement of the carbon-14 activity in a cypress beam in the tomb of the Egyptian Pharaoh Snefru, for example, established the date of the tomb as c 2600 BC.
cation-ratio dating
SYNONYMS OR RELATED TERMS: cation ratio dating
CATEGORY: technique
DEFINITION: A method of direct dating rock carvings and engravings, potentially applicable to Paleolithic artifacts with a strong patina caused by exposure to desert dust. The technique is based on the principle that cations of certain elements are more soluble than others; they leach out of rock varnish more rapidly than the less soluble elements, and their concentration decreases with time. A cation is an ion carrying a positive charge which moves toward the negative electrode/cathode during electrolysis.
chronometric dating
SYNONYMS OR RELATED TERMS: absolute dating; chronometry
CATEGORY: technique
DEFINITION: Any technique of dating that relies on chronological measurement such as calendars, radiocarbon dates, etc. and which give the result in calendar years before the present, or B.P. Most of these techniques produce results with a standard deviation, but they have a relationship to the calendar which relative dating techniques do not. Among the most useful chronometric dating techniques are radiocarbon dating, potassium argon dating, and thermoluminescence dating. Dendrochronology, the relationship of dated ancient trees with live trees has no standard deviation and is the most accurate of all, though not universally applicable. Chronometric dating has developed in the last 30 years and has revolutionized archaeology.
cross-dating
SYNONYMS OR RELATED TERMS: cross dating
CATEGORY: technique
DEFINITION: A correlation dating technique that can yield a relative or absolute age or chronology. The basis of cross-dating is the occurrence of finds in association. The assumption is that a particular type of artifact, for example a type of sword, when found in an undated context will bear a similar date to one found in a dated context, thus enabling the whole of the undated context to be given a chronological value. The method is based on the assumption that typologies evolved at the same rate and in the same way over a wide area or alternatively on assumptions of diffusion. Many of the chronologies constructed before the advent of chronometric dating techniques were based on cross-dating. New techniques such as radiocarbon dating showed some of the links established by cross-dating to be invalid, so the method has become somewhat discredited. However, its use is still helpful where recognizable products of dateable manufacture are found in undated contexts with no possibility of using a chronometric dating technique. So in the absence of geochronology, two cultural groups can only be proved contemporary by the discovery of links between them. If in culture A an object produced by culture B is found, A must be contemporary with, or later than, B. The term cross-dating ought strictly to be used only when an object of culture A is also found in proved association with culture B, when overlap of at least part of the time span of each is proved. Items having an established date, such as dated coins or buildings, or ceramics of known manufacture are most often used. By itself, a cross-dated chronology does not give absolute dates, but it may be calibrated by reference to other dating methods. A type of cross-dating has always been used in geology and stratigraphical sequences are often correlated by the assemblages of fossils they contain; this is known as biostratigraphy. The archaeological versions of cross-dating may have been developed directly out of the geological method and may have been based on a false analogy between biological fossils and archaeological artifacts.
dating
SYNONYMS OR RELATED TERMS: chronology
CATEGORY: technique
DEFINITION: The process by which an archaeologist determines dates for objects, deposits, buildings, etc., in an attempt to situate a given phenomenon in time. Relative dating, in which the order of certain events is determined, must be distinguished from absolute dating, in which figures in solar years (often with some necessary margin of error) can be applied to a particular event. Unless tied to historical records, dating by archaeological methods can only be relative - such as stratigraphy, typology, cross-dating, and sequence dating. Absolute dating, with some reservation, is provided by dendrochronology, varve dating, thermoluminescence, potassium-argon dating, and, most important presently, radiocarbon dating. Some relative dating can be calibrated by these or by historical methods to give a close approximation to absolute dates - archaeomagnetism, obsidian hydration dating, and pollen analysis. Still others remain strictly relative - collagen content, fluorine and nitrogen test, and radiometric assay. Other methods include: coin dating, seriation, and amino-acid racemization. The methods have varying applications, accuracy, range, and cost. Many new techniques are being developed and tested.
direct dating
CATEGORY: technique
DEFINITION: The use of a dating technique directly on the object being discussed, such as the charcoal from a fireplace or a piece of obsidian.
electron spin resonance dating
SYNONYMS OR RELATED TERMS: ESR
CATEGORY: technique
DEFINITION: A dating method using the residual effects of electrons' changing energy levels under natural irradiation of alpha, beta, and gamma rays. The technique enables trapped electrons within bone and shell to be measured without the heating that thermoluminescence requires; the number of trapped electrons indicates the age of the specimen. There are a number of factors that may cause errors with the method. Precision is difficult to estimate and varies with the type of sample.
faunal dating
CATEGORY: technique
DEFINITION: A method of relative dating based on observing the evolutionary changes in particular species of mammals, so as to form a rough chronological sequence.
fission track dating
SYNONYMS OR RELATED TERMS: fission-track dating; fission track age determination
CATEGORY: technique
DEFINITION: A chronometric dating technique based on the natural, spontaneous nuclear fission of Uranium 238 and its byproduct, linear atomic displacements/tracks. The basis for this technique is that a uranium isotope, U 238, as well as decaying to a stable lead isotope, also undergoes spontaneous fission. One in every two million atoms decays in this way. Fission is accompanied by an energy release which sends the resulting two nuclei into the surrounding material, the tracks causing damage to the crystal lattice. These tracks can be counted under a microscope after the polished surface of the sample has been etched with acid. The concentration of uranium can be determined by the induced fission of U 235 by neutron irradiation of the sample. Since the ratio of U 235 to U 238 is known, and is constant, a comparison of the number of tracks from natural fission and the number from induced fission will give the age of the sample. Though the method has been limited in its archaeological use so far, it has already proved a useful check method for potassium-argon dating for volcanic deposits at Olduvai Gorge, Tanzania, and obsidian, tephra beds, mineral inclusions in pottery, and some man-made glasses have also been dated. A further use of the method is based on the fact that fission tracks disappear if the substance is heated about 500? or so: thus a date achieved for clay (like a hearth), pottery, or obsidian that had been burnt gives the date of burning or firing, since previous fission tracks would have disappeared.
fluorine dating
SYNONYMS OR RELATED TERMS: 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.
formula dating
CATEGORY: technique
DEFINITION: Absolute dating using artifact attributes, especially applied to pipe stems and ceramics.
magnetic dating
SYNONYMS OR RELATED TERMS: paleomagnetic dating
CATEGORY: technique
DEFINITION: Any theoretically chronometric dating technique which uses the thermo-remanent magnetism of certain types of archaeological material. These methods use the known changes have taken place in the direction and intensity of the earth's magnetic field. Magnetic minerals present in clay and rocks each have its own magnetic orientation. When heated to the so-called blocking temperature, the original magnetic orientation of the particles is destroyed, and they will take on the orientation of the earth's magnetic field in a fixed alignment - which does not alter after cooling. These methods are most suitable for kilns and hearths. Once the direction of the archaeological sample has been determined, it may be possible to date it by fitting it to the secular variation curve established for the local area. There is no universal curve, since not only the earth's main field varies, but there are also local disturbances. Since the dating of the curve has to be constructed through independent dating techniques, and these are not available for every area, there are not established curves for every region. As a dating technique, it is strictly limited to those areas where dated curves have been established. A more recent dating technique using thermo-remanent magnetism is palaeointensity dating (archaeomagnetic intensity dating). The principle is that the thermo-remanent magnetism in burnt clay is proportional to the intensity of the magnetic field acting on the clay as it cools down. The measurement of its intensity, and a comparison with the intensity revealed by reheating in today's magnetic field, gives a ratio for the past and present fields which can be used to establish a curve of variation in the earth's magnetic field intensity. The method promises to be useful since direction in situ is not required and it can therefore be used for pottery and other artifacts as well as hearths and kilns.
mean ceramic dating
SYNONYMS OR RELATED TERMS: mean ceramic dating formula, mean ceramic date
CATEGORY: technique
DEFINITION: A statistical technique devised by Stanley South for pooling the median age of manufacture for temporally significant pottery types at American Colonial sites. It is especially applicable to 18th-century sites, where many distinctive ceramic types may be expected to occur in large numbers. The mean ceramic date is found by multiplying the sum of the median dates for the manufacture of each ceramic type of the frequency of each ceramic type and dividing this figure by the total frequency of all ceramic types. The median date for each type is arrived at from documentary evidence. One shortcomings is that the supposition that the median date coincides with the period of maximum use; another is the use of a count of sherds rather than whole vessels.
nitrogen dating
SYNONYMS OR RELATED TERMS: 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.
obsidian hydration dating
SYNONYMS OR RELATED TERMS: 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.
pipe-stem dating
CATEGORY: technique
DEFINITION: A method of calculating the date of American Colonial assemblages based on the variation in hole diameters in clay pipe stems. J.C. Harrington first drew attention to the fact that there is a general reduction in hole size from 1620-1800. Lewis Binford then developed a regression equation, thus: [ y = 1931.85 - 38.26x ] where y is the mean date for the group and x is the mean pipe-stem diameter for the sample. ("A New Method of Calculating Dates from Kaolin Pipe Stem Samples" Lewis R. Binford) The formula works well for the period 1680-1760 but fails to produce satisfactory results for post-1780 assemblages.
pollen dating
CATEGORY: technique
DEFINITION: Using local pollen sequences to provide a relative date for a site.
potassium-argon dating
SYNONYMS OR RELATED TERMS: K-A dating; potassium argon dating; radiopotassium dating
CATEGORY: technique
DEFINITION: An isotopic method of dating the age of a rock or mineral by measuring the rate at which potassium-40, a radioactive form of this element, decays into argon. It is used primarily on lava flows and tuffs and for ocean floor basalts. Potassium, which is present in most rocks and minerals, has a single radioactive isotope, K 40. This decays by two different processes into Calcium 40 and Argon 40. Though 89% decays to Calcium 40, it is not suitable for measurement since most rocks contain Calcium 40 as a primary element, and the amount caused by the decay of K 40 cannot be determined. The remaining 11% decays into the gas Argon 40, and this can be measured, along with the amount of potassium in the sample, to get a date. Dates produced by using this technique have been checked by fission track dating. The technique is best used on material more than 100,000 years old - such as the dating of layers associated with the earliest remains of hominids, notably in the Olduvai Gorge. Lava flows embedded with the deposits containing archaeological material have been dated.
radiocarbon dating
SYNONYMS OR RELATED TERMS: radioactive carbon dating, radiocarbon age determination, carbon-14 dating; radiochronometry; RC
CATEGORY: technique
DEFINITION: An absolute radiometric dating technique for determining the age of carbon-bearing minerals, including wood and plant remains, charcoal, bone, peat, and calcium carbonate shell back to about 50,000 bp. The technique is based on measuring the loss of radiocarbon (carbon-14) that begins disintegration at death at a known rate. It is one of the best-known chronometric dating techniques and the most important in archaeology presently. It can be used for the dating organic material up to 75,000 years old. It is based on the theory of Willard F. Libby (1947); his radioactive-carbon dating provided an extremely valuable tool for archaeologists, anthropologists, and earth scientists. When organic matter dies it ceases to exchange its carbon, as carbon dioxide, with the atmosphere, so its C14 dwindles by decay and is not replenished. Determination of the radioactivity of carbon from a sample will reveal the proportion of C14 to C12, and this will in turn, through the known rate of decay of C14, give the age of, or more accurately the time elapsed since the death of, the sample. Two things in the method have to be allowed for: first, the 'date' given is never exact. The +/- figure, which should always be quoted, is a statistical one, meaning that there is a 2 to 1 chance that the correct date lies within that bracket. Secondly, the rate of decay of C14 is based in all published examples on a half-life of 5730 +/- 40 years (after 5730 years, one half of the C14 will have disintegrated, after another 5730 years one half of the remainder, and so on). Correction tables are used to correct 'raw' radiocarbon dates (quoted as years ad or BC) into true dates (AD or BC). The method yields reliable dates back to about 50,000 bp and under some conditions to about 75,000 bp. One of the basic assumptions of the technique is that the amount of radiocarbon in the atmosphere has remained constant through time. It has now been established, with the dendrochronological sequence for the bristlecone pine, that the C14 concentration has fluctuated. The reasons for the fluctuation are not yet fully understood. The calibration of radiocarbon dates is therefore necessary in order to achieve an approximate date in calendar years. Dates quoted in radiocarbon years, before calibration, are written BC or bp (before present), as opposed to calibrated dates, written BC or BP. The original half-life for radiocarbon of 5,568 ? 30 years has been revised to 5,730 ? 40 years, though dates are normally published according to the old half-life in order to avoid confusion (the date can be adjusted for the new half-life by multiplying the old date by 1.029). All radiocarbon dates are quoted with a standard deviation. Ideally, a series of dates should be obtained for any deposit as a series may cluster around a central point. New refinements continue to improve the technique's accuracy as well as extend the range of dates which can be achieved. A previous limit of 50,000 years on the age of material which could be dated, set by the limits on the ability of the proportional counter used to record beta particle emissions, has been extended to 70,000 years by the use of isotopic enrichment, the artificial enrichment of the C14 to C12 ratio.
radiometric dating
SYNONYMS OR RELATED TERMS: radiometric assay; radiometrics
CATEGORY: technique
DEFINITION: Dating by measuring processes which involve the decay of radioactive isotopes and yielding absolute age estimations. Radiocarbon, potassium/argon, and uranium series dating employ the known rate of decay, expressed by their half-lives. Fission track dating similarly employs spontaneous nuclear fission, which also occurs at a known rate.
relative dating
SYNONYMS OR RELATED TERMS: relative dates; relative dating techniques
CATEGORY: technique; chronology
DEFINITION: Dating methods where phases or objects can be put into a sequence relative to each other, but which are not tied to calendrically measured time. It is the sequencing of events or materials relative to another but without linkage to ages in years bp (before present) or calendar years. A relative date is a date which can be said to be earlier than, later than, or contemporary with an event but which (unlike an absolute date) cannot be measured in calendar years. When archaeologists say that event A occurred before or after event B, they have a relative date for A. Before the advent of chronometric dating techniques, all dating was relative except where links with historical events could be proved. Some of these techniques, mainly stratigraphy and seriation, are still useful where chronometric dates cannot be obtained. Theoretically, floating chronologies which cannot be tied to an absolute date (e.g. certain dendrochronological sequences) are relative chronologies even though the techniques are essentially chronometric.
sequence dating
CATEGORY: technique
DEFINITION: A method developed by Sir Flinders Petrie (for Egyptian predynastic cemeteries) for dating a group of similar objects according to their archaeological sequence. By studying the typology the changing forms of certain artifacts, they may be set into sequence. Petrie used it to arrange undated graves into a hypothetical (relative) chronological order according to the typology and association of the artifacts found in them (based on a stylistic seriation of Egyptian pre-dynastic tomb pottery). Artifacts found at other sites were then correlated with the sequence and given a sequence date. The technique can only be used to determine whether one type of artifact is earlier or later than another; it cannot show length of time between two. This type of seriation, when combined with cross-dating, is still useful in the absence of other dating methods.
trapped charge dating
CATEGORY: chronology
DEFINITION: A form of dating relying on the fact that electrons are trapped in minerals' crystal lattices as a function of background radiation; the age of the specimen is the total radiation received, divided by the annual dose of radiation
tree-ring dating
SYNONYMS OR RELATED TERMS: dendrochronology
CATEGORY: technique
DEFINITION: The use of annual growth rings in trees to date archaeological sites.
uranium dating
SYNONYMS OR RELATED TERMS: uranium series dating, uranium series disequilibrium dating
CATEGORY: technique
DEFINITION: A method of dating based on measuring the rate of radioactive decay of uranium isotopes in bone and other organic remains to the stable isotope of lead. It has proved particularly useful for the period before 50,000 years ago, which lies outside the time range of radiocarbon dating. Each of the isotopes decays through a series of radioactive daughter isotopes until a stable isotope of lead is reached. Three daughter isotopes are created and decay with half-lives useful for dating: ionium, proactinium, and radium. Several uranium dating methods exist and material datable by these methods includes: aragonitic coral, speleothem, travertine, mollusk shell, marl, bone, teeth, caliche, calcretes, peat, wood, and detrital sediment.
varve dating
CATEGORY: technique
DEFINITION: A technique for producing chronometric dates based on the annual formation of layers of sediment on lake and river beds in glacial regions. Seasonal fluctuations in particle size and speed of sedimentation take place. During the winter, ice melting is very slow, melt-water streams do not contain much water, and they flow slowly, carrying little material. During the summer, melting accelerates, melt-water streams flow faster and carry more material. The supply of sediment to the ice-marginal lake varies with the season. A varve chronology, similar to a tree-ring chronology may be set up. But as with tree rings (see dendrochronology) the varves will vary from year to year, depending on the rapidity of the thaw, quantity of summer rain, winter snow, etc., the variations showing some correlation with the sunspot cycle. Such varve chronologies have been built up for Scandinavia and are used to date the retreat of the Weichselian ice-sheet. Varve dating has a greater significance than just for local dating, since frequently there is enough organic material to allow radiocarbon dates to be calculated. There is therefore the possibility of using the calendrical varve chronology to calibrate radiocarbon dates. Its use for archaeological dating is rather limited in that sites have to be related to the geological changes (the ice-sheet moraines or changing Baltic sea-levels) before their dates can be determined. Swedish pioneer Baron Gerard de Geer discovered in the late 19th century that these could be counted and correlated or linked over long distances, which gave him a timescale of 12,000 years and fixed the end of the Ice Age at about 10,000 years ago.

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