Carbon dating charcoal bone
Learn More Materials such as shells and other materials where a date on the inorganic carbon (carbonate) is to be done typically undergo acid etching before pretreatment.Learn More The occurrence of contamination can be natural or artificial.The ensuing atomic interactions create a steady supply of c14 that rapidly diffuses throughout the atmosphere.Plants take up c14 along with other carbon isotopes during photosynthesis in the proportions that occur in the atmosphere; animals acquire c14 by eating the plants (or other animals).Natural contamination pertains to the introduction of contaminants to the sample by its surrounding material.For example, bone samples can be contaminated by the presence of limestone or organic acids in the soil (like humic or fulvic acids) where the bones were found.
In contrast, methane made from petroleum products had no measurable radioactivity.
Compared to conventional radiocarbon techniques such as Libby's solid carbon counting, the gas counting method popular in the mid-1950s, or liquid scintillation (LS) counting, AMS permitted the dating of much smaller sized samples with even greater precision.
Regardless of the particular 14C technique used, the value of this tool for archaeology has clearly been appreciated.
Even then, there remains an inbuilt age effect, albeit somewhat reduced.
In the late 1950's, the issue of presample age was identified as a causal factor in the difficulties encountered in accurately cross-dating the Julian calendar with that of the Yucatan Maya of Lowland Mexico.