These collisions create secondary cosmic rays in the form of energentic neutrons.When these neutrons collide with nitrogen-14 in the atmosphere carbon-14 can be created.
This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers. The short half-life of carbon-14 means its cannot be used to date extremely old fossils.
Carbon-14 dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharohs among other things. Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 remains undecayed).
Carbon dating is used to determine the age of biological artifacts up to 50,000 years old.
This technique is widely used on recent artifacts, but teachers should note that this technique will not work on older fossils (like those of the dinosaurs which are over 65 million years old).
Once an organism dies, it stops taking in carbon-14.
The carbon-14 it contained at the time of death decays over a long period of time, and the radioactivity of the material decreases.
It can be used on objects as old as about 62,000 years.
Follow the links below to learn more about radiocarbon dating. Radiocarbon dating uses carbon isotopes A special kind of radiocarbon dating: Bomb radiocarbon dating What is an isotope?
C-14 is produced in the upper atmosphere when nitrogen-14 (N-14) is altered through the effects of cosmic radiation bombardment (a proton is displaced by a neutron effectively changing the nitrogen atom into a carbon isotope).
The new isotope is called "radiocarbon" because it is radioactive, though it is not dangerous.
Materials that originally came from living things, such as wood and natural fibres, can be dated by measuring the amount of carbon-14 they contain.