Problems with relative dating techniques
And, if so, has today’s uniform level prevailed throughout the recent past?After showing the essential uniformity of carbon-14 in living material, Libby sought to answer the second question by measuring the radiocarbon level in organic samples dated historically—materials as old as 5,000 years from sources such as Egyptian tombs.To effectively determine the fate of spilled oil in the environment and to successfully identify source(s) of spilled oil and petroleum products is, therefore, extremely important in many oil-related environmental studies and liability cases.This article briefly reviews the recent development of chemical analysis methodologies which are most frequently used in oil spill characterization and identification studies and environmental forensic investigations.Fortunately, neither effect has been significant in the case of older samples submitted for carbon-14 dating.The ultimate cause of carbon-14 variations with time is generally attributed to temporal fluctuations in the cosmic rays that bombard the upper atmosphere and create terrestrial carbon-14.In short, all parts of the carbon cycle were seen to be invaded by the isotope carbon-14.
Expressed as a fraction of the contemporary level, they have been mathematically converted to ages through Improvements in measurement accuracy and the ever-mounting experience in applying carbon-14 dating have provided superior and more voluminous data with which to better answer Libby’s original questions.
Of more recent date was the overcompensating effect of man-made carbon-14 injected into the atmosphere during nuclear bomb testing.
The result was a rise in the atmospheric carbon-14 level by more than 50 percent.
With correction for radioactive decay during the intervening years, such old samples hopefully would show the same starting carbon-14 level as exists today. His conclusion was that over the past 5,000 years the carbon-14 level in living materials has remained constant within the 5 percent precision of measurement.
A dating method was thus available, subject only to confirmation by actual application to specific chronologic problems.Newly created carbon-14 atoms were presumed to react with atmospheric oxygen to form ) molecules.