The technique is based on the principle that cations of certain elements are more soluble than others; they leach out of rock varnish more rapidly than the less soluble elements, and their concentration decreases with time.
A cation is an ion carrying a positive charge which moves toward the negative electrode/cathode during electrolysis.
The method is based on the assumption that typologies evolved at the same rate and in the same way over a wide area or alternatively on assumptions of diffusion.
Many of the chronologies constructed before the advent of showed some of the links established by cross-dating to be invalid, so the method has become somewhat discredited.
The test is used mainly in association with the fluorine test and radiometric assay, as in the cases of Piltdown and Swanscombe Man. The basis of cross-dating is the occurrence of finds in association.
The assumption is that a particular type of artifact, for example a type of sword, when found in an undated context will bear a similar date to one found in a dated context, thus enabling the whole of the undated context to be given a chronological value.
This method yields an absolute date within about 50 years."CATEGORY: technique DEFINITION: Any of a serious of methods of analyzing bone samples, especially by measuring fluorine, uranium, nitrogen -- also called the FUN technique -- or by using stratigraphy.
However, racemization is very much affected by environmental factors such as temperature change.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.It is fairly reliable for deep-sea sediments as the temperature is generally more stable.SYNONYMS OR RELATED TERMS: archaeomagnetic intensity dating, archaeomagnetism, palaeointensity dating, archaeomagnetic age determination CATEGORY: technique DEFINITION: A chronometric method used to date objects containing magnetic materials -- especially for buried undisturbed features such as pottery kilns, earthen fireplaces, and brick walls -- which can be compared to known schedules of past magnetic alignments within a region and fluctuations in the earth's magnetic field.