Tephrochronology is a method for geochemical correlation of unknown volcanic ash (tephra) to geochemically fingerprinted, dated tephra.Tephra is also often used as a dating tool in archaeology, since the dates of some eruptions are well-established.Exposure dating uses the concentration of exotic nuclides (e.g.Cl) produced by cosmic rays interacting with Earth materials as a proxy for the age at which a surface, such as an alluvial fan, was created.Two methods of paleomagnetic dating have been suggested (1) Angular method and (2) Rotation method.
Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite.
This, however, is a misnomer, as the chronology is based on Ussher's work alone and not that of Lightfoot.
Ussher deduced that the first day of creation fell upon, October 23, 4004 BC, in the proleptic Julian calendar, near the autumnal equinox.
A number of radioactive isotopes are used for this purpose, and depending on the rate of decay, are used for dating different geological periods.
More slowly decaying isotopes are useful for longer periods of time, but less accurate in absolute years.