How It Works: Carbon has 3 isotopic forms: Carbon-12, Carbon-13, and Carbon-14.The numbers refer to the atomic weight, so Carbon-12 has 6 protons and 6 neutrons, Carbon-13 has 6 protons and 7 neutrons, and Carbon-14 has 6 protons and 8 neutrons.Therefore, radiocarbon dates need to be calibrated with other dating techniques to ensure accuracy.
Rodents, for example, can create havoc in a site by moving items from one context to another.
Natural disasters like floods can sweep away top layers of sites to other locations.
The Mayan calendar used 3114 BC as their reference.
More recently is the radiocarbon date of 1950 AD or before present, BP.
The Greeks consider the first Olympic Games as the beginning or 776 BC.