Radiocarbon dating problem

This would decrease the release of carbon-12 to the atmosphere through the decay of vegetation.

Third, for carbon-14 dating to be accurate, the concentrations of carbon-14 and carbon-12 must have remained constant in the atmosphere.

The industrial revolution greatly increased the amount of carbon-12 released into the atmosphere through the burning of coal.That means if you took one pound of 100 percent carbon-14, in 5,730 years, you would only have half a pound left.Carbon-14 is created in the upper atmosphere as nitrogen atoms are bombarded by cosmic radiation.The water in these subterranean chambers would not have contained carbon-14, as the water was shielded from cosmic radiation.This would have upset the ratio of carbon-14 to carbon-12. Libby also assumed that the amount of carbon-14 being presently produced had equaled the amount of carbon-12 he assumed that they had reached a balance.