Before radiocarbon dating
Shells of known age collected prior to nuclear testing have also been dated ( to ascertain the effects of old carbon (i.e., local marine reservoir effects). However, the most common materials dated by archaeologists are wood charcoal, shell, and bone. In brief, radiocarbon dating measures the amount of radioactive carbon 14 (14C) in a sample.
Radiocarbon analyses are carried out at specialized laboratories around the world (see a list of labs at: When a biological organism dies, the radioactive carbon in its body begins to break down or decay.
The amount of radioactive carbon (C14) that had been in the organism when it was alive begins to decrease at death as it loses nuclear particles through radioactive decay.
In effect, the "clock" starts ticking when death occurs. After 5,568 years, half of the original amount of C14 in the living organism remains.
The introduction of "old" or "artificial" carbon into the atmosphere (i.e., the "Suess Effect" and "Atom Bomb Effect", respectively) can influence the ages of dates making them appear older or younger than they actually are.
This is a major concern for bone dates where pretreatment procedures must be employed to isolate protein or a specific amino acid such as hydroxyproline (known to occur almost exclusively in bone collagen) to ensure accurate age assessments of bone specimens.
Alone, or in concert, these factors can lead to inaccuracies and misinterpretations by archaeologists without proper investigation of the potential problems associated with sampling and dating.
To help resolve these issues, radiocarbon laboratories have conducted inter-laboratory comparison exercises (see for example, the August 2003 special issue of Radiocarbon), devised rigorous pretreatment procedures to remove any carbon-containing compounds unrelated to the actual sample being dated, and developed calibration methods for terrestrial and marine carbon. Radiocarbon dating can be used on either organic or inorganic carbonate materials.
Regardless of the particular 14C technique used, the value of this tool for archaeology has clearly been appreciated.Many different organic (carbon containing) materials may be dated using the radiocarbon method.Wood, seeds, hair, bone, insect remains, peat, and charcoal are just a few of the materials that are radiocarbon dated.The archaeologists record and analyze the changes in types and styles of human-made items from different levels according to the principle explained below.Sediments are usually laid down in horizontal beds.