the 'fossil' tracks counted) viz., exposes the sample to a known number of low energy (thermal)neutrons which induce fission of a small fraction of the uranium atoms in the sample.The sample is immersed in the proper chemical reagent, which allows rapid attack of the narrow regions of damage and slower dissolution of the adjacent unchanged material.The emergence of man through the process of biological and cultural evolution is a story of long span of time.
Such treatment are used to create etch pits of optical size, each one making a single fission site.
The method requires sufficient uranium to produce a track density, which can be counted within reasonable time.
Third, the varves may form frequently rather than annually depending on the pattern of the melting.
However, instead of the limitations, varve analysis can be used indirectly for archaeological dating.
The proportion of these D-amino acids increases with time.
Thus the age of the skeletal materials that are found in archaeological sites can be estimated by determining the amount of change, racemisation that has occurred.
Besides these two a number of other absolute method like thermo luminescence, dendrochronology, Electron Spin Resonance etc.
also proved very helpful for dating various events of the past.
In fact, chronology is one of the most fundamental issues in and perhaps a characteristic of archaeology.