Ams radiocarbon dating definition
The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. This makes it possible to tell the age of substances that contain carbon. Dates obtained are usually written as before present ('present' is 1950).
Atmospheric nuclear weapon tests almost doubled the concentration of Radiocarbon dating, also known as the C14 dating method, is a way of telling how old an object is. Plants take up atmospheric carbon dioxide by photosynthesis, and are eaten by animals, so every living thing is constantly exchanging carbon-14 with its environment as long as it lives. In 1958 Hessel de Vries showed that the concentration of carbon-14 in the atmosphere varies with time and locality.
For the most accurate work, variations are compensated by means of calibration curves.
The method was developed by Willard Libby and his colleagues at the University of Chicago in 1949.
A form of radiometric dating used to determine the age of organic remains in ancient objects, such as archaeological specimens, on the basis of the half-life of carbon-14 and a comparison between the ratio of carbon-12 to carbon-14 in a sample of the remains to the known ratio in living organisms. A technique for measuring the age of organic remains based on the rate of decay of carbon 14.
The carbon 14 present in an organism at the time of its death decays at a steady rate, and so the age of the remains can be calculated from the amount of carbon 14 that is left. The cells of all living things contain carbon atoms that they take in from their environment.
Carbon 14 is continually being created in the Earth's atmosphere by the interaction of nitrogen and gamma rays from outer space.
Mezhirich is a large open air site where several mammoth bone huts with hearths and pit features were used between about 14,000-15,000 years ago.About 10 large pits, with diameters between 2-3 m (6.5-10 ft) and depths between .7-1.1 m (2.3-3.6 ft) were found surrounding the mammoth-bone structures at Mezhirich, filled with bone and ash, and are believed to have been used as either meat storage facilities, refuse pits, or both.Internal and external hearths surround the dwellings, and these are filled with burnt mammoth bone. Stone tools are dominated by microliths, while bone and ivory tools include needles, awls, perforators, and polishers.Mezhirich was discovered in 1965 by a local farmer, and excavated between 19 by a series of archaeologists from the Ukraine and Russia. Joint international excavations were conducted by scholars from Ukraine, Russia, the UK and the US well into the 1990s.
More recent Accelerator Mass Spectrometry (AMS) radiocarbon dates suggest a shorter chronology for all mammoth bone settlements, between 15,000 and 14,000 years ago.