At that time the radioactive disintegration takes over in an uncompensated manner. only half the C-14 will remain after the half-life period.
Consequently, the chronology worked out for the geological deposits helped in dating the prehistoric tools found in these deposits. There are certain antiquities and potteries which by themselves have acquired a dating value.Sir Flinders Petrie had worked out a formula for dating the finds on the basis of the thickness of the deposit.According to him a period of hundred years may be granted for the accumulation of a deposit of one and a half feet.Antiquities and potteries of Roman origin were found in association with the finds of Indian origin.With the aid of these dated imports it was possible to date the associated Indian objects to the first two centuries A. Similarly NBP and PGW has helped in fixing the chronology of numerous sites. Sometimes dates are also obtained with the assistance of astronomy.The types and forms or shape of these pots and also the antiquities under go evolutionary changes in cource of time, It is further assumed that all living animals derive body material from the plant kingdom, and also exhibit the same proportion of C-14 material.