26 March 1985        

Mr. Kevin H. Wirth
Director of Research
Students for Origins Research
P. O. Box 203
Santa Barbara, CA 93116

Dear Mr. Wirth:

Tom Jukes sent me copies of your exchange of correspondence and your Document 32 to PACIFIC DISCOVERY. I note that in the latter you have incorrectly characterized my testimony at the Arkansas trial by omitting nearly the entire substance of my comments on Gentry's pleochroic halos. About my testimony you say, "Although it is conceivable to test Gentry's findings, his challenge was dismissed at the trial by USGS expert witness for the ACLU Brent Dalrymple us a 'minor mystery' with prohibitively high costs for building a test mechanism and that was that. No more discussion." Your statement is untrue and since my testimony is a matter of public record I am mystified as to the source of your information. Please allow me to summarize what I have said about Gentry's conclusions, both at the trial and at the Santa Barbara AAAS meeting.

First and foremost, Gentry's "hypothesis" is unscientific because he proposes fiat creation of the Earth, and a fiat-induced flood. In science, miracles are a no-no. Miracles may occur (although I am unconvinced that they do), but they are the subject of philosophy and religion, not science.

Second, there have been several credible alternate hypotheses advanced in the scientific literature for the origin of anomalous Po-halos, including erasure or modification of the inner halos by the Alpha radiation from another isotope, such as Po-210, migration of uranium-series elements through the rocks by either fluid migration or diffusion, and modification of halos by heat, pressure, and chemical change during metamorphism. Gentry has disputed all of these explanations but has disproved none of them and I find his arguments unconvincing.

Third, there are numerous problems with halo interpretation and there is a distinct possibility that the Po halos are not what they appear to be. Known difficulties include coloration [p. 297] reverals due to saturation effects, attenuation of alpha particle ranges by the radioactive inclusion, dose dependence of halo radii, the lack of adequate data on the relation between energy and distance in the various mineral types in which halos are found, and the probable but unknown effects of crystal imperfections and chemical impurities.

Thus, the identification and interpretation of the so-called Po-halos is a very uncertain business. We don't know with certainty, a) that they are Po-halos, or b) how they are formed. This is the background of my description to the court of Po-halos as one of sciences many "tiny myateries"—mysterious because their explanation is uncertain and tiny because I think that they are a problem of minor importance (which explains why few scientists bother with them). The fact that the origin and interpretation of Po-halos is uncertain lends no credibility to Gentry's unscientific "hypothesis". Science is full of mysteries, that is why there are still employment opportunities for scientists.

As for Gentry's "challenge", it is nonsense for several reasons. First, the synthesis of a hand-sized piece of granite in the laboratory would neither prove nor disprove Gentry's "hypothesis", only demonstrate that someone had figured out the technology and spent the money to make large pieces of granite. Thus, for its stated purpose it would be a worthless experiment and that is one reason why no serious scientist will take Gentry's challenge seriously. The problems in completely crystallizing igneous rocks in the laboratory are well known and are due to scale, i.e., it is not always easy to reproduce in the laboratory what nature requires hundreds of thousands or millions of years to do. The principal difficulties are nucleation, kinetics, time, and volume.

Gentry's insistence on a hand-sized piece also is somewhat of a problem. Experimental petrologists find it most convenient and sufficient to work with equipment of reasonable size and cost. As a result, most high-pressure and temperature bombs use charges of less than a gram in weight. An apparatus to synthesize a hand-sized piece of an igneous rock would be immense and costly, and as far as I know, no experimental petrologist has found it necessary to build and utilize such an apparatus when the smaller, less costly equipment serves the purposes of science.

Second, Gentry's "challenge" is absurd because it is not necessary to perform Gentry's experiment to prove his hypothesis incorrect because it is already proven false. Gentry's main point seems to be that granites (and here we don't know whether he is using the term loosely to include all granitic rocks or specifically to include only granite in the strict compositional sense) do not cool from a liquid rock melt, but there is ample proof that he is wrong. Igneous textures are distinct and can be duplicated in the laboratory using a variety of materials, including rocks. Igneous rocks with igneous textures can also be observed forming in nature. One example is Kilauea Iki lava [p. 298] lake, where drilling over a period of several years has recovered a continuum of samples in progressive stages of crystallization by cooling of a rock melt. Other examples include lava flows, many of which crystallize completely within a year or so. The textures of these lavas are virtually identical to granites, which is not too surprising. Recall, if you will, that the primary difference between volcanic and batholithic intrusive rocks (granites) is that the former reaches the surface whereas the latter does not. Furthermore, the sequence of crystallization of minerals in granite, which can be determined by any experienced petrologist for any given rock, invariably agrees with the order predicted by thermodynamic calculations and laboratory phase equilibria studies for minerals crystallizing from a rock melt of granitic composition.

Third, Gentry seems to think that the Precambrian consists entirely of "primordial" granites and that this "primordial basement" is overlain by the stratified rocks of the world (deposited during the Flood, of course). At best this view is naive. The Precambrian consists of rocks of virtually every type, including lava flows, glacial deposits, and continental and oceanic sedimentary rocks. In fact, the oldest rocks on Earth (3.5 to 3.8 billion years—Western Australia, Greenland, southern Africa) are lava flows and shallow marine sedimentary rocks. These are intruded by younger granitic rocks. There are no "primordial granites" as per Gentry, or at least none have been found.

As for as I am concerned, Gentry's challenge is silly. He has proposed an absurd and inconclusive experiment to test a perfectly ridiculous and unscientific hypothesis that ignores virtually the entire body of geological knowledge. Science is not required to respond to such a challenge and the fact that Gentry's proposal has been ignored does not entitle him to any claim to victory.

As you can see from the above (and as you should have recalled from my remarks at the AAAS symposium, my objections to Gentry's interpretation of Po-halos are far more numerous and substantive than, as you say in your document, the "high costs for building a test mechanism". You also imply that I have no substantive objections to Gentry's proposal. In so doing you have falsely represented my position and incorrectly reported my testimony at the Arkansas trial. I trust that you will take immediate steps to correct the error.

Yours truly, G. Brent Dalrymple

cc:	S. Warrick W. Bennetta T. Jukes W. Meikle