Author: Chris Stassen
Subject: FAQ: Evaluation of ICR Grand Canyon Research Project [DRAFT]
NOTE: Austin has promised to publish all of his data at some point, and
this work cannot really be completed until that happens.
However, since Austin has seen fit to (before publishing a full
paper) make all sorts of claims for his results in non-technical
literature, this FAQ makes use of the information available at
the time of writing.
The Grand Canyon looks something like this:
___\ /__________________ <-- Paleozoic rocks
...\ \ \ \ \ \ .... <-- Angular unconformity
.....\ \ \ \ \ ......
.......\ \ \ ............
.........\ .................. <-- Metamorphic rocks
Steve Austin of the ICR wrote _Impact #224_ (Austin 1991), claiming
that he has derived a Rb/Sr isochron "age" for lava flows on the
Uinkaret Plateau in excess of 1.3 billion years (several of these
flows spill into the canyon). The Cardenas Formation, a tilted
layer at the bottom of the canyon (below the angular unconformity)
is generally accepted as being about 1.1 billion years in age.
Clearly, something is wrong here. Lava flows which spill
off the plateau into the canyon cannot be older than the canyon
itself. The canyon can't be older than the rocks that it is cut
into. The flat sediments can't be older than those below the angular
unconformity (as they were deposited on top). Even young-earthers
admit the validity of such geologic relationships (though they
argue for greatly compressed time-scales.)
Austin's apparent thesis: Rb/Sr dating of the feature which must be
the youngest gives a value older than that which must be the oldest,
therefore the method does not work. (Of course, then, all radiometric
results can "justifiably" be ignored.)
What is going on here? Has Austin really (as he claims) struck
a blow against the "foundation" of isochron dating? Would any
(mainstream) geologist have attempted to obtain an "age" in the
same manner, or attached the same significance to it?
First, let's turn back the clock to _Impact_ #178 (Austin 1988), an
earlier paper on the same lava flows. A slightly different "isochron"
for the same flows is produced, using data obtained from an earlier
study by a mainstream geologist (Leeman 1974).
Leeman's paper contains quite a bit more data (with a lot more
"scatter") than are reproduced in _Impact_ #178. Leeman's entire data
do not fit well enough to an isochron line to lead any geologist to
expect the resulting "age" to be reliable. However, when the data are
narrowed down to a small range of stratigraphic positions, the remaining
data points fall relatively near an isochron line.
However, the same stratigraphic data (as used for the selecting
process) clearly indicates that the flows did not all occur at the same
time (the flows fall into two different stratigraphic "stages",
according to _Impact_), one of the requirements of isochron dating is
ignored right from the start. The resulting "age" might have
significance -- as the age of the common source material for all of
the flows -- but it clearly cannot be used to date the flows themselves
(the geologic evidence indicates that there IS no single common "age"
for all the flows).
In fact, this sort of "pseudo-isochron" is documented in the
mainstream literature and is relatively well-understood. _Impact_ #178
even contains two references to the mainstream explanation for such an
"isochron," one of them being (Faure 1986, p. 147).
Now, back to _Impact #224_ (Austin 1991), which contains an "isochron"
constructed from rock samples taken by the ICR. The same lava flows as
selected from Leeman's paper in _Impact #178_ are used, but (suspiciously)
any mention of the "mainstream" explanation for the "pseudo-isochron"
has been dropped and two important claims are made:
1) The "isochron" is claimed to be "unexpected." (This is clearly
false, as the paper trail -- _Impact #178_ -- shows that Austin
knew he'd get a pseudo-isochron long before the ICR obtained a
single rock sample of their own.)
2) The "isochron" is claimed to apply to the flows themselves. (This
is clearly false, for reasons described above.)
Those claims form the basis of the key criticisms of the "Grand Canyon
1) If Austin wished to -- as he claims to -- "test" Rb/Sr dating, why
did he have to "rig" the test by performing it on a formation where
the result was known in advance? Perhaps even he knows that Rb/Sr
dating produces values convenient to mainstream expectations most
of the time?
2) Austin's attempt to apply the dating method is obviously bungled,
and the basis of the error is openly admitted in print. No geologist
would construct an isochron plot from samples of differing
stratigraphic positions and expect the resulting "age" (if the data
points did fall on a line) to represent the age of each individual
Austin, 1992, "Excessively Old ``Ages'' For Grand Canyon Lava Flows",
_Impact_, Number 224, February.
Austin, 1988, "Grand Canyon lava flows: A survey of isotope dating
methods", _Impact_, Number 178, April.
Faure, 1986, _Principles of Isotope Geology_ Second Edition. ISBN
0-471-86412-9. 589 pp.
Leeman, 1974, "Late Cenozoic Alkali-Rich Basalt from the Western Grand
Canyon Area, Utah and Arizona: Isotopic Composition of Strontium",
in _Geological Society of America Bulletin_, Vol. 85, November,