That is, we can use carbon-14 dating on a given tree-ring (the 8000-year sequence having been assembled from the overlapping tree-ring patterns of living and dead trees) and compare the resulting age with the tree-ring date.
A study of the deviations from the accurate tree-ring dating sequence shows that the earth's magnetic field has an important effect on carbon-14 production.
Figure 19.5, curve C, shows the dipole field strength calculated from measurements of magnetism of lava flows and of artifacts such as pottery and bricks, whose age can be determined.
The curve is roughly fitted to mean values determined about every 500 to 1,000 years...
Creationists don't want their readers to be distracted with problems like that -- unless the cat is already out of the bag and something has to be said.
The water coming out of the hose is analogous to the continuous production of carbon-14 atoms in the upper atmosphere.That is, the equilibrium point should have long since been reached given the present rate of carbon-14 production and the old age of the earth.The next step in Henry Morris' argument was to show that the water level in our barrel analogy was not in equilibrium, that considerably more water was coming in than leaking out.It's a great argument except for one, little thing.The water is coming out of the hose at a steady rate as our model assumed!When the dipole moment is strong, carbon-14 production is suppressed below normal; when it is weak, carbon-14 production is boosted above normal.What the magnetic field does is to partially shield the earth from cosmic rays which produce carbon-14 high in the atmosphere.(The barrel is made deep enough so that we don't have to worry about water overflowing the rim.) Henry Morris argued that if we started filling up our empty barrel it would take 30,000 years to reach the equilibrium point.Thus, he concluded, if our Earth were older than 30,000 years the incoming water should just equal the water leaking out.Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question.Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates.