However, racemization is very much affected by environmental factors such as temperature change.If there has been significant change in the temperature during the time in which the object is buried, the result is flawed.Other problems of contamination have occurred, so the technique is not fully established.
Libby's conclusion, with allowance for SYNONYMS OR RELATED TERMS: radiocarbon dating CATEGORY: technique DEFINITION: The occurrence of natural radioactive carbon in the atmosphere allows archaeologists the ability to date organic materials as old as 50,000 years.dating technique relies on the progressive decay or disappearance of the radioactive parent with time.This is now a common method for estimating the age of a carbonaceous archaeological artifacts.SYNONYMS OR RELATED TERMS: half-value period, radioactive half-life CATEGORY: term DEFINITION: The time taken for half of a given amount of a radioactive substance to decay into a non-radioactive substance.It is also defined as the time taken for half the quantity of a methods.
This decay rate, expressed as a statistical constant, is different for each isotope.
If a sample, such as a piece of wood, has half of the original amount of radiocarbon remaining, then a time equivalent to the half-life has passed since it died. 40 years, while the half-life of radioactive potassium, used in SYNONYMS OR RELATED TERMS: amino-acid dating; aminostratigraphy; amino-acid racemization, amino acid racemization CATEGORY: technique DEFINITION: A method of absolute (chronometric) dating which is hoped to fill the gap between radiocarbon dates and potassium-argon dates.
It is used for human and animal bone and other organic material.
Specific changes in its amino acid structure (racemization or epimerization) which occur at a slow, relatively uniform rate, are measured after the organism's death.
The basis for the technique is the fact that almost all amino acids change from optically active to optically passive compounds (racemize) over a period of time.
Aspartic acid is the compound most often used because it has a of 15,000-20,000 years and allows dates from 5,000-100,000 years to be calculated.