Radiocarbon dating to calendar years
This discovery meant that there are three naturally occurring isotopes of carbon: Whereas carbon-12 and carbon-13 are stable isotopes, carbon-14 is unstable or radioactive.Carbon-14 is produced in the upper atmosphere when cosmic rays bombard nitrogen atoms.Three isotopes of carbon are found in nature; carbon-12, carbon-13 and carbon-14.Carbon-12 accounts for ~99.8 % of all carbon atoms, carbon-13 accounts for ~1% of carbon atoms while ~1 in every 1 billion carbon atoms is carbon-14.The Greeks consider the first Olympic Games as the beginning or 776 BC.The Muslims count the Prophet’s departure from Mecca, or the Hegira, as their beginning at AD 662.In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
Relative dating stems from the idea that something is younger or older relative to something else.
A unique characteristic of 14C is that it is constantly formed in the atmosphere.
Production and decay 14C atoms are produced in the upper atmosphere where neutrons from cosmic rays knock a proton from nitrogen-14 atoms.
The site number identifies the specific archaeological site the sample came from.
The New Zealand numbers are part of the New Zealand Archaeological Association Site Recording Scheme.