Describe one method of relative dating
Subsequently, the calibration of that date provides a time interval where the event or object being dated can be situated (eg, 1275-1425 AD).
Radiocarbon dating, however, can only be used for dating objects that are less than 50 000 years.
This method is primarily applied to projectile points and ceramic vessels.
These present many characteristics that are used for comparing them, such as morphology and raw materials in the case of stone tools, and decorative techniques and motifs in the case of ceramics.
Crossdating is an important principle in dendrochronology.
It consists in comparing and matching two or more series of ring widths measured on different trees.
Indeed, carbon 14 (14C) is formed from the reaction caused by cosmic rays that convert nitrogen into carbon 14 and then carbon dioxide by combining with carbon 12 (12C) and carbon 13 (13C ), which are stable carbon isotopes.
Following the death of an organism, any exchange ceases and the carbon 14, which is radioactive and therefore unstable, slowly begins to disintegrate at a known rate (half-life of 5730 years, ie, after this period only half of the total carbon 14 present at the time of death remains).
A sample requires 10 to 20 grams of matter and usually consists of charred organic material, mainly charcoal, but bones (zooarchaeology) and shells can also be dated using this technique.
An initial reading dates the specimen which is then calibrated by considering this date and its correspondence with the measurable level of carbon 14 stored over time in the growth rings of certain tree species, including redwood and pine bristol.
The results of radiocarbon dating are expressed in years and include a time range (eg, 630± 60 BP).
However, this method is sometimes limited because the reoccupation of an area may require excavation to establish the foundation of a building, for instance, that goes through older layers.
In this case, even if the foundation of the building is found in the same stratigraphic level as the previous occupation, the two events are not contemporary.
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Typology Typology is a method that compares reference objects in order to classify them according to their similarity or dissimilarity and link them to a specific context or period.