"In summary, both theory and experiment show that changes in alpha, beta- and electron capture decay rates are not only rare but exceedingly small. Even the largest observed change in Be(7) would have a negligible effect on a calculated radiometric age. Also of importance is the fact than no changes have ever been detected in any of the isotopes used for dating and none of significance are theoretically expected. Of the physical and chemical processes that affect meteorites and rocks from the earth and moon, including pressure, temperature, gravity and magnetic and electric fields, none should affect decay to any signifiacnt degree. Thus, we can be confident that for all practical purposes the radiometric clocks used for geological dataing "tick" at unchanging rates."
G Brent Dalrymple p88-98 "The age of the earth"
S.G Brush has examined the creationist's criticisms of radiometric dating and has concluded that "They are based on ignorance or misunderstanidning".
S. G Brush "Finding the age of the earth: By physics or by faith ?" Journal of Geological education 30(1982):35.
Morris went even further by claiming that geologists established the ages of rocks long before radioactivity was known by interpreting the position of the fossils within strata. While geologists established relative ages by applying the principle of superposition, the absolute age of the fossils could NOT be established by this method. Yet Morris continues(d) to assert that geological ages are determined by the index fossils they contain.(Scientific creationism p 134-137). (Strahler: Science and earth history ch 17).