However, in reality the ratio varies with time and place.
C-14 is created in the upper layers of the atmosphere, by the bombardment of Nitrogen with cosmic rays.
Limitations of the Technique Every scientific method has its limitations.
Contamination disturbs the ratio of carbon isotopes found in situ, in the sample.It only means that these need to be used with caution and with a knowledge of the limits of their accuracy.C-14/C-12 Ratio is Not Absolute The accuracy of this method is largely dependent on an assumed absolute ratio of C-14 to C-12, which is supposed to have remained constant over time.This may lead to an inaccurate determination of age. However, error in determination of age, by carbon dating methods can be compensated by using other dating techniques, which use radioactive elements, other than carbon.This dating technique is inaccurate at times but its error levels are very low and certainly not inaccurate enough to be called wrong.Accuracy of this dating technique is not perfect, but it has given remarkably precise results, when tested to calculate age of artifacts, whose age was known, by other methods.