Potassium dating accuracy
Perhaps the earth was made from older pre-existing matter, or perhaps decay rates were briefly faster for some reason. Geologic time is divided up into periods, beginning with the Precambrian, followed by the Cambrian and a number of others, leading up to the present.
When one considers the power of God, one sees that any such conclusions are to some extent tentative. Some fossils are found in Precambrian rocks, but most of them are found in Cambrian and later periods.
Since there doesn't seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate.
However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over 500 million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old.
Thus radiometric dating methods appear to give evidence that the earth and meteorites are old, if one accepts the fact that decay rates have been constant.
Even the creationist accounts that I have read do not adequately treat these issues.Potassium 40 (K40) decays to argon 40, which is an inert gas, and to calcium.