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There were other estimates but the calculations were hotly disputed because they all were obviously flawed by uncertainties in both the initial assumptions and the data.
It does not work well on sedimentary rocks because these rocks are composed of debris from older rocks.
By the early 1960s, most of the major radiometric dating techniques now in use had been tested and their general limitations were known.
No technique, of course, is ever completely perfected and refinement continues to this day, but for more than two decades radiometric dating methods have been used to measure reliably the ages of rocks, the Earth, meteorites, and, since 1969, the Moon.
Some of the methods have internal checks, so that the data themselves provide good evidence of reliability or lack thereof.
Commonly, a radiometric age is checked by other evidence, such as the relative order of rock units as observed in the field, age measurements based on other decay schemes, or ages on several samples from the same rock unit.For example, a method based on a parent isotope with a very long half-life, such as C method can only be used to determine the ages of certain types of young organic material and is useless on old granites.