Radioactive carbon 14 dating is dependent on
Experiments done with the radioactive isotopes of Uranium-238 and Iron-57 have shown that rates not only do vary, but can, in fact, be altered by changing the environment surrounding the samples.
on July 16, 1945, and the subsequent above ground testing between 19, caused a rise in neutrons which in turn increased Carbon-14 concentrations around the world.
There is no instrument on earth that can detect Carbon-14 in a specimen that is supposedly older than 18 half-lives. There are, however, many false assumptions that must be made in order to derive Carbon-14 dates and the knowledge of these false assumptions demonstrates the uselessness in this other-wise supposedly useful not varied over the years. There is ample evidence to prove that quite the opposite is true.
Then, in another 5,730 years, a second decay period would occur, leaving one quarter of a pound.
The process would continue, halving the amount left every 5,730 years until, theoretically, nothing remained of the original pound.
If one were to believe the Bible, the earth was surrounded by a layer of water vapor between Creation and the Flood.
If this water vapor did exist in the past, then it would have effectively shielded the atmosphere from much of the cosmic radiation.