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short-lived nutritional plants, branches from a hearth instead of relatively large trunks of long-lived trees).
Finally, we should keep in mind that in order to check the samples for an eventual contamination or material mixing from different layers during the excavation, it is advisable always to collect all the appropriate types of samples even if there is no need for them to be dated which case there is a direct functional relation between the analysed organic matter and the archaeological co-finds, e.g.
100-200 years older than the date the timber was cut even if it was used for the first time.
It is of course very well known that it is difficult to realise problems of this nature and finally to be able to answer the questions of re-use, the direct relation etc.
the presence of animal excreta and bat droppings in the excavated area. In practise though, it is possible to date smaller quantities of sample provided that the age is younger than ca. TABLE 2 shows the minimum required quantities of different types of sample.
The ash from the cigarettes, fat, oil, human hair or hair from brushes, as well as food remains are common contaminating factors. It is worth noting that the reduction of the quantity of the sample results in the increase of the preparation and measurement time of the sample, as well as to the increase in the age error.
The collection of the samples for radiocarbon dating should be done together with the archaeologists and the researchers of the laboratory in order to obtain the best results.The optimum required quantity of sample for the determination of reliable dates with the smaller possible error fluctuates in each laboratory according to the radiocarbon technique used. Every sample submitted for dating is one among hundreds, which come yearly to the laboratory.TABLE 1 shows the required quantities for different types of sample in the case of the LABORATORY OF ARCHAEOMETRY of N. So, it is important that every sample is fully documented with all related archaeological information, which is needed for the laboratory staff to draw the conclusions.The measurement precision depends not only on the initial amount of sample available and the age of the sample but also on the shape of the calibration curve at the time period to which the sample belongs.The same accuracy of measurement of two samples can result into a different final accuracy after calibration as can be seen in the examples of Table 1.
wood remains in a grave with offerings, carbonised seeds in vases, charcoal in an amphorae or from a hearth on a house which case there is no obvious functional relation between the analysed sample and the archaeological material, but the amount of organic matter is in favour of some relation, e.g.