Elements can be transported into a sample or leach out of a sample.Scientists will reject theories about the age of the earth that do not conform to the norm.Radiometric dating techniques are thus based on sound scientific principles, but rely on so many basic assumptions that Bible believers need not have their faith shattered by data derived from these techniques. What do rock layers on the Earth's crust tell us about our origins and the age of the earth?
If even a small percentage of the limestone deposits were still in the form of living marine organisms at the time of the Flood, then the small amount of carbon-14 would have mixed with a much larger carbon-12 reservoir, thus resulting in a drastically reduced ratio.
It's assumed that the clock was set to zero when the study material was formed.
This requires that only the parent isotope be initially present or that the amount of daughter isotope present at the beginning is known so that it can be subtracted.
While there is no proof that the rates were different in the past than they are today, there is also no proof that they were the same.
Thus radioactive dating relies purely on assumptions.