Methods for determining the age of archaeological finds PDF Print E-mail
Friday, 14 November 2014 21:59

When we hear that archaeologists have discovered a particular artifact, which, for example, 5,300 years old, then take it for granted, although we can not know how the scholars so accurately determine the age of the finds. There are different methods of five and we'll tell you.

The most classic method of dating archaeological stratigraphy considered. Basically it is applied in the case of excavations of settlements that existed long period of time.
The fact is that in the places where people live, the soil layer is constantly increasing - in connection with construction projects, earthworks and other elements of human activities. This layering is called cultural layer that looks like a layer cake. And each layer in it - a reflection of a certain period of life of the city.

It preserved ancient buildings, construction, household refuse, traces of fire. Moreover, the land can tell us about the fate of a particular family. During the excavations of ancient settlements are often found burned house with his hosts who failed to escape in time.

How does she dating? In fact, by comparison with layers of other monuments, about which more is known, for example from written sources, the found finds, which are characteristic for a certain period, as well as on the structure and color and composition of the soil.

For example, in the cities of Volga Bulgaria, survived the Mongol-Tatar invasion, pre-Mongol layer composition, and often the color is different from the later layers. In addition, the stratigraphy allows to establish a chronological sequence, as in the undisturbed cultural layer of the lower layers of the ancient upper.

Therefore it is so important untapped cultural layer. The one that was destroyed during the construction or black diggers not only unfit for stratigraphic analysis, but generally will not be able to tell about the history of this place, because all the cultural layers and, consequently, historical periods will be mixed. Unfortunately, the destruction of cultural layers - a fairly common pattern.

comparative method

The comparative method to determine the relative, and in some cases, accurate dating. It is a purely historical: layers date back to ancient inscriptions on the finds, coins.

For a comparison of this method is characteristic of archaeological data from written sources describing life in the study area or a certain way of life of the people. Of course, if they exist. The comparative method is practically useless for dating preliterate cultures, especially in the absence of near them ancient written civilizations.

In the same category can be attributed, and a method of dating on the artistic features articles and images. For example, for certain periods and cultures existed creative features, whether a particular pattern, machinery manufacturing and other. When finding general rules of recognition of such stylistic features to date objects can be fairly accurately.

But to date the layer with artistic features, you need to start dating themselves artistic features. Here comes to help with routine method called "typological" mixed stratigraphy. It is based on a combination of finds in the typological series - a series of things that are repetitive or progressive symptoms. To establish the date of this series must have several archaeological sites that contain this type of thing. The length of time limited extreme dates in this series, and will determine the date type. In this case the accuracy of the dating depends on the number of archaeological sites. If enough of them, then the correctness of dating can be verified by the distribution date objects. When a statistically sufficient number of items of the same type can have a chance to calculate an interval during which this type was in use.

radiocarbon method

For absolute dating archaeologists used radiocarbon analysis, which starts from the content of organic carbon for radioactive C-14.

All living organisms that metabolize ordinary carbon from the atmosphere, along with him and absorb the radioactive carbon-14. Therefore, the concentration of radiocarbon lifetime is almost the same as that of trees and plants, as in human and animal bodies. But after his death in the process of destruction of organics begins assimilated radiocarbon. If we compare the trees felled 5,000 years ago, modern wood, it would appear that in the old wood of the isotope C-14 is twice as less. Thus, the radiocarbon method can determine the age of carbonaceous material to 70-100 thoUSAnd years, but not anymore. For more "ancient" finds, for example, for dating dinosaur bones, apply other isotopes, such as beryllium-10.

Despite the fact that radiocarbon analysis allows to accurately determine the time of death of organics, it does have its disadvantages and they are many. A first drawback lies in the fact that it dates only organic matter but not during the creation of a historical artifact. For example, in the case of icons, it can be dated material from which it is made, but for the manufacture of high-quality counterfeits can pick up and old material. Roughly speaking, the age of the board still is not talking about the age of the picture.

Another disadvantage of this method is that the result may be distorted if the sample was heavily contaminated carbon material of a later period. In this case, the definition of age can make a huge mistake. Accuracy of the method is currently in the range 70-300 years, at first study it was much more.

It is on the likelihood of such errors supporters cite the authenticity of the famous Shroud of Turin, which were also radiocarbon analysis. As a result, it has been dated to the interval from 1260 to 1390. Skeptics immediately declared it a medieval forgery, to which its advocates have suggested about the pollution of the Shroud carbon in the fire of the XVI century. By the way, to test the validity of the results analyzed simultaneously with the shroud three other tissue samples: cape Louis IX of the XIII century, the burial shroud of Egyptian woven around 1100, and the fabric wraps Egyptian mummy dating from about 200 a year. In all three cases, laboratory results coincided with the original data.

paleomagnetic method

One of the most common findings in archeology most periods is ceramic. Today it can be dated to within a dozen years, defining the firing, the latter melting furnace, and so on. This is possible thanks to the paleomagnetic method based on the variability of Earth's magnetic field and magnetized materials properties at high temperatures under its influence. Thus, the transition iron substances from liquid to solid state, the minerals stored in the resulting so-called residual magnetization. In this case it will be the same vector with the orientation of the magnetic field of the Earth at the time of formation of the mineral. The obtained information about the state of the magnetic field of the earth at the time of firing correlated with the geologic time scale, composed using paleontological, radiometric and other data, and the results obtained.

The main disadvantage of the paleomagnetic method is that for accurate data, it is necessary to study the object does not move after firing, and this condition is satisfied only in rare cases.



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