It is based on the fact that amino acids (the building blocks of all proteins) exist in two mirror image forms, both of which otherwise have the same chemical structures.
The L-amino acid molecule form has an extension to the left, while the D-amino acid form has an extension to the right.
SYNONYMS OR RELATED TERMS: thermoluminescence dating, thermoluminescent dating; TLCATEGORY: technique DEFINITION: Chronometric method of dating ceramic materials by measuring the stored energy created when they were first fired.
It is based on the principle that ceramic material, like other crystalline non-conducting solids, contains small amounts of radioactive impurities such as potassium, uranium, and thorium, which emit alpha and beta particles and gamma rays causing ionizing radiation.
The amount of thermoluminescence from a heated sample is used to determine the number of trapped electrons resulting from the absorption of alpha radiation.
The quantity of light emitted will depend on three factors -- the number of flaws in the crystal, the strength of the radioactivity to which it has been exposed, and the duration of exposure.
Each region has its own unique master sequence since weather patterns are not the same from one area to another.
Historians, for example, know that Shakespeare's play Henry V was not written before 1587 because Shakespeare's primary source for writing his play was the second edition of Raphael Holinshed's Chronicles, not published until 1587.
Accuracy for the technique is generally claimed at ? It overlaps with radiocarbon in the time period for which it is useful, spanning 50,000-300,000 years ago, but also has the potential for dating earlier periods.
It has much in common with electron spin resonance (ESR).
Relative dating methods are unable to determine the absolute age of an object or event, but can determine the impossibility of a particular event happening before or after another event of which the absolute date is well known.
In this relative dating method, Latin terms ante quem and post quem are usually used to indicate both the oldest and the most recent possible moments when an event occurred or an artifact was left in a stratum.
An age determination technique in which the amount of light energy released in a pottery sample during heating gives a measure of the time elapsed since the material was last heated to a critical temperature.