Dating in Archaeology
The emergence of man through the process of biological and cultural evolution is a story of long span of time. For the archaeologist and the prehistorian who deals with that long history of man, time aboslute the most important consideration. The sequence of development of culture or the relationship between events that represent culture can be established only when events can be placed in proper time.
Chronology, the study of events in time absolute dating methods anthropology, is hence the central xbsolute of archaeologist, like the geologist who deals with the story of absolute dating methods anthropology history. In fact, chronology is one of the most fundamental issues in and perhaps a characteristic of archaeology. Archaeologists use several methods to assign ages to events of the past. They are engaged in defining the stages of hominid evolution and their artifactual record, and the assignment of a chronology to these stages.
Chronology is the science of measuring anthropoligy and ordering of the things in time. According to the Dictionary of Anthropology, the word chronology means the science of computing dates or treaties showing arrangement of events with dates. In other words, Chronology is the arrangement of events, or the materials which represent them, in the absolute dating methods anthropology of their occurrence in time. Any study of the origins of human must be set in a chronological context.
Till the early part of 19th century quite a good number of relative dating methods have been used in archaeological studies. A short description of each of these methods is given below:. The application of varve dating is restricted by several factors. First, it is because varve accumulation occurs only to glacial areas of the world. Second, many absolute dating methods anthropology the Pleistocene glacial areas has receded nowadays and affecting the supply of sediments.
Therefore outside Scandinavia it is difficult methovs find continuous sequence of varves reaching the present. Absolute dating methods anthropology longest sequence known goes back only 17, years. Third, the varves may form frequently rather than annually depending on the pattern of the melting. However, instead of the limitations, varve analysis can be used indirectly for archaeological dating. It has been used in Baltic area, North America, South America and Athropology.
In North America, Ernst Antevs has made several attempts to relate Pleistocene geological formations in the American Southwest to events that produced varves in the northern parts of North America. Fission Absolute dating methods anthropology Technique - This technique dates material ranging from 20 years to 1,, years before the present.
Fission track dating is based upon the fact that over geological time spontaneous fission of uranium impurities produces minute sub- microscopic damage trails in the most insulating solids, both long period of time. As the damage sites are permanent, a simple count of their number allows an age dqting be measured. The density of track depends on the uranium content as well as the age of the sample i. The sample is immersed in the proper chemical reagent, which allows rapid attack of the narrow regions of damage and slower dissolution of the adjacent unchanged material.
Such treatment are used to create etch pits of optical size, each one making a single fission site. The method requires sufficient uranium to produce a track density, which can be counted within reasonable time. Amino Acid Racemisation, a method of absolute dating applied to human fossils is developed very recently. This is based on the fact that all living organisms have L-amino acid in their absolute dating methods anthropology and after death, and over a long period of time all the L-amino acids except glycine undergo change called racemisation and became non protein D-amino acid.
The proportion of these D-amino acids increases with time. Thus the age of the skeletal materials xbsolute are found in archaeological sites can be estimated by determining the amount of change, racemisation that has occurred. Dting Acid Racemisation AAR is a useful comparative dating method with great potential, but it introduces problems of calibration and the requirement of an intimate knowledge of the palaeoenvironmental conditions of the bone deposition site.
Most suitabl e materials. Effective datin g rang e. Organic mater i als, i norgan ic carbonates. Poor sampling, co ntam i natio n b y younger mater i al s. Vol c a n ic rock o r materia ls. U n li m i tedc o arse calibration. Av a il ab ili t y o f u n w eathered v o lc an ic rock, s a mp le preparation, c o ntam i nation.
Thermol um i n i sc e nce. Requires calibrated regional framework framework. D endrochrono l og y. R eg i o antropology specifi c. The hominid mrthods record is extremely fragmentary, and chronology is essential in unravelling the complex record of human development. Carbon dating discovered inproved very helpful for establishing absolute dating in various archaeological sites. Potassium-Argon K40 method extends the range of absolute dating beyond the limit of radio-carbon.
Besides these two a number of other absolute method like thermo luminescence, dendrochronology, Electron Spin Resonance etc. In applying the dating methods to a particular site, it is important to consider the purposes and limitations of each dating method - relative or absolute. With the help of stratigraphic position of the site or with the help of some associated finds dates of the site can be derived relatively, whereas with the help of several absolute dating around the world, archaeologists are now able to construct a single, multiregional time frame for all hominid evolution.
Depending upon the type of problem, accuracy required, materials available for dating, problem of contamination will decide what type of technique one should use for dating. All dating techniques have their merits and demerits and this has to be kept in mind by the archaeologist. It is essential to apply several dating methods for cross-checking the dates and to build a concrete chronology. Buy These Notes in PDF