Radiometric Dating measures the age of fossils.
This is the most crucial to the young earth believers. If they yield on the true age of the earth, then all is lost WRT Adam and Eve.
Hence there are many attacks on the methodology of determining the age of rocks.
Here are a few:
A. Reference to cases where the given method did not work and thereby ignoring these potential problems with rock samples such as,
alteration, possible argon loss, the low content of uranium in basaltic rocks, or isotopic ratios that may be inherited from source areas.
B. Claims that the assumptions of a method may be violated :
e.g. Constancy of radioactive decay rates .
From Snelling we get....
"Indeed, the obvious way to explain the gross disagreements between these dates is that the decay rates have been different in the past than they are today" (GCDV, p. 39).
Just Curious: Why doesn't Snelling develop this theme and explain the thermal consequences to the planet of compressing 4.5 billion years of radioactivity into less than 6,000 years, and the consequences to the cosmos of changing Planck's constant. He could surely get a Nobel prize for undermining all of physics nucular theory.
See http://www.noanswersingenesis.org.au/hiding_the_numbers_woody_henke.htm for further rebuttal to their attacks on radiometric dating.