What nuclide is commonly used in the dating of artifacts
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.However, there may be other explanations for this apparent age. I also believe that the evidence indicates that the earth has recently undergone a violent catastrophe.We are told that of all the radiometric dates that are measured, only a few percent are anomalous.This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points.For potassium 40, the half-life is about 1.3 billion years.In general, in one half-life, half of the parent will have decayed.
In general, in n half-lives, only 1/(2^n) of the original parent material will be left.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.