I have considered the days of old, the years of ancient times.
Suppose your friend has a bag of M&Ms. She is counting each color separately. You have five orange M&Ms, and you add them to her mix. But this stops her being able to count them properly. She wants you to remove your five orange M&Ms from the six orange M&Ms that she has. But they are now mixed. How do you know which were the original M&Ms and which were the ones you added?
Naturally occurring lead is comprised of three stable isotopes – 204Pb, 206Pb, and 207Pb. 206Pb and 207Pb are products of the radioactive decay of uranium isotopes 238U and 235U respectively. 204Pb is assumed to be “common” lead – that is, long-age geologists assume that 204Pb comes from the original formation of the Earth.
When rock is exposed at the Earth’s surface, scientists will attempt to date it by U-Pb dating, by measuring the amount of lead and uranium. If these elements were simple, we could assume that all the lead had been derived from uranium and could calculate the age, given that we know the half-life of uranium. In practice, the elemental composition is more complicated. For example, it is not possible to tell the difference between an atom of 206Pb that might have been in the rock originally and one formed by radioactive decay, anymore than your M&M friend could distinguish between orange M&Ms from different sources.
Creation geologists have shown that new rocks added to the crust during the year-long Flood would have accumulated lead isotopes by accelerated decay. As usual, a biblical model makes more sense than an evolutionary deep-time bias.
We read in Your word, Lord, how You made the heavens and the earth and how Your creation took six days. We marvel at the way You have made all things well. Amen.
Author: Paul F. Taylor
Ref: Snelling, A.A. (2017), Problems with the U – Pb Radioisotope Dating Methods—1 Common Pb, Answers Research Journal 10 (2017):121-167, , accessed 7/27/2017. Image: Zircon crystal on calcite, Rob Lavinsky (2010), license: Creative Commons Attribution-Share Alike 3.0 Unported.