These melted crystals, and therefore the impact, have been dated by the 40Ar/39Ar method at 74.1 Ma (million years; Izett and others 1998), but that is not the whole story by a long shot.The impact also created shocked quartz crystals that were blasted into the air and subsequently fell to the west into the inland sea that occupied much of central North America at that time.As a result, this method is not used except in rare and highly specialized applications.Other dating techniques, like K-Ar (potassium-argon and its more recent variant 40Ar/39Ar), Rb-Sr (rubidium-strontium), Sm-Nd (samarium-neodynium), Lu-Hf (lutetium-hafnium), and U-Pb (uranium-lead and its variant Pb-Pb), have all stood the test of time.In order to accomplish their goal of discrediting radiometric dating, however, creationists are faced with the daunting task of showing that a preponderance of radiometric ages are wrong — that the methods are untrustworthy most of the time.Not only that, they have to show the flaws in those dating studies that provide independent corroborative evidence that radiometric methods work.These methods provide valuable and valid age data in most instances, although there is a small percentage of cases in which even these generally reliable methods yield incorrect results.Such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or misapplication of the techniques (no one is perfect).
Other creationists have focused on instances in which radiometric dating seems to yield incorrect results.
This is a tall order and the creationists have made no progress so far.
It is rare for a study involving radiometric dating to contain a single determination of age.
The creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons.
First, it provides no evidence whatsoever to support their claim that the earth is very young.