It is often argued by creationists that radiometric dating methods doesn't work.
To support this Answers in Genesis has used dating of rocks from Mt St Helens' eruption.
In short the article report that material from the eruption was dated by a well known lab, and dated to be more than a million years old, while it was in fact just a few decades old.
The conclusion in the article is, that this shows that the dating method doesn't work.
I have contacted the laboratory that made the dating, mentioned in the report, and confronted them with the claims that their datings support the idea that radiometric dating methods doesn't work.
Here is the answer:
Dear Mr. Frello,
me preface my remarks by saying that: 1) I am unable to comment on any
work we may have done for a client. I will limit my remarks to the data
presented in the website. 2) Geochron Laboratories has no affiliation
with, nor does it endorse the work of, the Institute for Creation
Research or that of any other so-called creation science or intelligent
with any empirical analytical method, the potassium argon method for
age determination of rocks relies on certain assumptions. It is also
limited in its accuracy by measurement uncertainties. In the case of
the classic K-Ar dating technique, it is assumed that the rock initially
contains no argon except maybe some with an air-like isotope
composition (i.e. it contains no so-called radiogenic argon 40), that
the radioactive potassium 40 in the sample decays by a known and
constant half-life process to Ar 40, and that the Ar 40 produced from
this decay is fully retained by the rock until the measurement is made.
From these and other assumptions and from measurements of the actual
potassium and radiogenic Ar 40 content of the rock, an age may be
calculated estimating how long ago the rock was formed.
first assumption, that the rock contains no radiogenic Ar 40 at the
time of its formation, is not always completely true. Rocks deposited
in contact with much older rocks can pick up some of the argon 40
contained by the latter through diffusion at the high temperatures
associated with their formation. This can lead to rocks of apparently
older age than their true age. This can be particularly a problem with
very young rocks (a few million years old is young by geologic
standards), where such “excess” argon 40 can form a very large
proportion of the total argon 40 in the rock.
subjects of argon retention, diffusion and the introduction of "excess"
argon have been widely studied in the legitimate scientific
literature. The subject is complex, but suffice it to say, it is very
well known under what circumstances problems with radiometric dating can
arise. Methodologies for the analysis of very young volcanic rocks
(less than a few million years old) have also improved over the last 30
years or so. Some rocks are nonetheless problematic; not all samples
can be reliably dated. If you wish to pursue this subject in more
detail, look into the work of G. B. Dalrymple, a leading researcher in
the area. Some of his work is mentioned in these web pages:
in the case of very young rocks (less than a few million years old),
the uncertainties associated with the classic K-Ar measurement of very
small quantities of argon 40 begin to rise rapidly. This is especially
true if there is any significant quantity of normal air argon in the
sample as well, as is often the case.
case described in the website of K-Ar dates of Mount St. Helens dome
rock, assuming that the samples are in fact accurately represented, is
an extreme case where the limitations of the methodology would be
expected to be tested. It would take only a small quantity of
extraneous Ar 40 diffusing in from older host rocks to produce a
non-zero positive age. If this is what happened, then the apparent age
should vary with potassium content of the rock fractions; the higher the
potassium content, the lower the calculated age. The whole rock and
feldspar dates probably represent higher potassium content materials,
while the amphibole and pyroxene components are likely very low in
potassium content. As can be seen, the former produce younger ages and
the latter older ones.
K-Ar method for age determination of rocks, when used for the dating of
suitable materials, and with a recognition of the limitations of the
method, is a reliable approach for determination of the very old age of
many rocks. The use of an extreme case at the expected limits of the
method as a critique of the method as a whole is not justified, and in
this case is likely disingenuous.
my opinion, it is not generally worth the effort to engage Biblical
literalists on these subjects, as they are often immune to reason and
evidence. They are typically not scientists in their approach to
knowledge, but rather apologists and propagandists for a predetermined
“truth”. Some use the language of science to sound respectable, but
much of what they say, when examined closely, is deceptive and a
distortion of the actual state of modern science.
I hope that this explanation is clear. Please let me know if I can provide you with any additional information.