|email - February 2011|
|by Do-While Jones|
We received several excellent emails reacting to last November’s article on missing isotopes. This month we will address two of them.
The feature article in last November’s newsletter examined the so-called “missing isotopes,” and the implication drawn by some people concerning the age of the Earth. Rod was one of the people who questioned the validity of determining the age of the Earth from elements found (and missing) in stars.
Thanks so much for taking the time to write this article. It has helped me in my understanding of the issue as well as giving me further support for refutation of the assertion when it comes up in FaceBook discussions.
The assertion has been that they do see evidence of these various isotopes in stars and supernovas, based on gamma ray emissions, however I see no reason to conclude that the same elements present in stars must be present in planets. That is, they assume (in stellar evolution) that these elements were present when the earth formed, and then since they aren't present now they conclude stellar evolution is true and thus long ages is true. Assuming stellar evolution to support stellar evolution is the fallacy of begging the question.
I thought of one other issue related to the missing isotope assertion, and that is that radiometric dating assumes zero daughter elements present at the time of annealing, yet the missing isotope assertion assumes non-zero amounts of various other elements at the time of the earth forming. Since it appears to me the two assertions are opposite it reveals the arbitrariness of the two assertions. Is there something you can see that I am missing in this?
Rod has a valid point that measurements of the isotopes present in stars (whether they are correct or not) have nothing to do with the isotopes present on Earth, unless one makes some unverifiable assumptions about how and when the Earth and stars were formed. The same thing can be said for dating the Earth by dating moon rocks. It is as silly as trying to date the Mayan pyramids by dating the pyramids in Egypt. (One would have to assume all the pyramids were built by the same civilization.)
Rod asked if he was missing something about how radiometric dating works, and he was. This gives us an opportunity to set the record straight.
Not all radiometric methods assume the absence of daughter elements initially. In particular, the isochron method assumes a value determined by the Y-intercept of the plot. 1 The other methods assume the various levels of isotopes in a previous newsletter. 2 Evolutionists assume these non-zero values because they (sometimes) give the "right" answers.
Potassium-argon dating does, as Rod says, assume no argon gas remains when the lava hardens. It turns out that not all the argon escapes from the hot lava, resulting in the notorious "excess argon" that makes modern lava flows appear to be millions of years old, so that's a bad assumption. We went through the calculations nearly 7 years ago showing how little initial argon it would take to make a modern lava flow appear to be millions of years old using the potassium-argon dating method. Here is the conclusion of that article.
Suppose you put one grain of black sand in a cement truck filled with white sand. That one grain of black sand would represent a little more than the typical amount of “excess argon” in modern lava flows. Furthermore, that one grain of sand is roughly equivalent to the amount of argon that would be produced by decay of potassium in 1.5 million years. 3
Potassium decays into argon so slowly that just a few argon atoms trapped in the molten lava makes the lava appear old. Lava, when it comes out of a volcano, isn’t pure enough to be dated by measuring the amount of argon in it.
Another form of radioactive dating that depends upon no initial daughter elements is zircon dating. David wrote an excellent email telling why evolutionists believe zircon dating is accurate.
Hello, I thought I would write and comment on the article on radioactive age dating. There are many things I can point to that are scientifically inaccurate about the article.
You brought a point about how the amount of uranium (U) and lead (Pb) are know [sic] when the rock formed. You said it can't be know [sic], but rather a guess has to be made. Well here's where the disconnect lies. When a geologists [sic] wants to do uranium-lead dating the amount of U and Pb in the "rock" is not normally measured to determine the age of the rock. The amount in one single mineral crystal is measured, again not in the rock! You are correct to say the amount in the rock can not be known, and that's likely true, but the amount in a mineral can be known because when a mineral forms it doesn't form randomly with all the known elements in its structure, only a limited range of elements or very specific ratios of elements, and that's the key.
For example, table salt is sodium + chloride (NaCl), with almost nothing of anything else. Therefore you can say with almost absolute certainty that it formed with a 1:1 ratio (50-50% of Na and Cl). That's true for all Table salt (halite) on the planet. This formula has very little variation. If there was such a thing as Na-Cl dating (which there's not because Na doesn't decay to Cl) the ratio to start in the minerals would be 50% - 50%. It doesn't even matter what the ration [sic] of the rock is, only the mineral!
So anyway with Uranium-lead dating its [sic] the same. The minerals used are ones that incorporate Uranium when they form but DO NOT incorporate lead. They won't include lead because the lead atom is either not the correct size or it atomic charge (+ or -) is incorrect. When the mineral zircon forms it takes in uranium but not Lead, so geologists use zircon to determine the age of the zircon crystal, and then the age of the zircon crystal gives the age of the rock because it's part of the rock. Also, the mineral monazite uses rare earth elements, phosphate and oxygen when it forms. But since uranium is the right size and has the right atomic charge a little bit of uranium is also incorporated when monazite crystallizes into a solid mineral, but no lead is used. So for monazite, the other elements used during its formation (besides Uranium and lead) are disregarded because they mean nothing for determining the age of the monazite formation only the uranium and lead are of interest. So when monazite forms the ratio of uranium to lead is 100% to 0% and over time the uranium decays to lead at a constant rate. The resulting lead is trapped by the solid structure of the monazite crystal. Take it to a lab for analysis and they measure the uranium and lead ratio in that one single monazite crystal, again NOT THE ROCK!
David is very nearly right. Uranium doesn’t decay at a constant rate—it decays at an exponential rate; but we know what he means. He means that uranium decays at a known rate, and he’s right about that. Other than that minor slip of the tongue (and a few grammatical errors), he’s right.
He is especially right when he says, “table salt is sodium + chloride (NaCl), with almost nothing of anything else.” It’s that “almost nothing” part that makes zircon dating unreliable.
Uranium decays to lead much slower than potassium decays to argon. Therefore, it takes even less initial lead to make zircon crystals appear to be older than they are.
The purity of zircon crystals depends upon a process called “fractional crystallization.” As rocks cool, minerals tend to separate because different minerals have different freezing points. If rocks cool slowly enough, the zircon crystals will harden at a different time than other minerals in the rock harden, effectively separating the uranium-containing zircon crystals from other minerals containing lead that might be in the molten rock. There’s a cute little experiment at the Northwestern University website showing how this works by partially freezing apple juice. 4
Sulzer Chemtech uses fractional crystallization to purify crystals on an industrial scale. There is a sixteen page document on their website explaining how their process works. They say,
The phase diagrams clearly demonstrate that pure A and pure B crystals can in principle be obtained over a range of temperatures and concentrations as indicated by the corresponding freezing point curves. It is further evident that any mother liquor, coexisting with any species being crystallized, must be less pure than the crystals themselves. In such cases, the crystalline phase is covered by impure mother liquor which should be removed in order to secure purity. For this reason the removal of residual mother liquor in order to secure a pure product is an important operation both in large scale plants and in the laboratory. 5
Scientists have great ideas. Engineers put those great ideas into practice. In the process, engineers learn that things are easier said than done. The devil is in the details. Scientists often overlook some small, but very important, fact that isn’t discovered until an engineer tries to use the idea for a practical purpose.
Fractional crystallization sounds so simple on paper. But when Sulzer Chemtech tried to use the process to purify chemicals, they discovered it wasn’t so simple after all. You can’t just slowly cool a mixture of melted minerals and expect them to separate into perfectly pure crystals. The document on their website describes the different processes they use for fractional crystallization, and recommend “Static Crystallization – for medium to high product purities” and “Falling Film Crystallization – for medium to very high product purities.” The important point to realize is that even under carefully controlled laboratory conditions, they can only get “very high product purities.”
When crystals form in nature, the “impure mother liquor” isn’t drawn off “in order to secure purity.” That’s why, as David correctly points out, unprocessed salt crystals are made of sodium chloride and “almost nothing of anything else.” Naturally occurring crystals are naturally impure. In some cases, it is the impurity that makes the crystals beautiful.
On paper, zircon crystals don’t contain any lead at all, just as David wrote. But naturally-occurring crystals aren’t perfectly pure. They do contain some lead impurities. Since uranium decays to lead much more slowly than potassium decays to argon, the naturally occurring lead in zircon crystals is a more serious problem than the naturally occurring argon in lava.
Geodes are Iowa’s state rock. They are generally (but not perfectly) round, generally (but not always) hollow, usually (but not always) with crystals inside. When I went to school, I was taught that geodes were a perfect example of fractional crystallization. The different concentric rings of differently colored minerals, and the crystals inside, were thought to have formed at different times as the rock cooled.
When researching this article, I discovered the origin of geodes is now disputed. Apparently the most obvious example of natural fractional crystallization isn’t quite so obvious anymore. According to the Iowa Department of Natural Resources, geologists now believe that some further modification is necessary after the fractional crystallization to complete the process.
The origins of geodes have vexed geologists for a considerable time, and many hypotheses have been put forward. The most recent geologic research, however, agrees on three general points: 1) Geode precursors were concretions (nodules formed by outward growth around some nucleus) which grew within soft, unlithified sediment. 2) The outer shells of these concretions were replaced subsequently by chalcedony. 3) The interiors of the concretions were dissolved, leaving a hollow space into which quartz crystals could grow. The composition of the original concretions is unclear, though geologists propose they were either limestone or anhydrite, a fairly soluble calcium sulfate mineral related to gypsum.
The minerals now seen inside geodes were transported in groundwater solutions and then precipitated as replacements of the geode walls or as crystalline growths within their hollow interiors. The ultimate source of the mineralizing waters remains speculative. Many common geode mineral[s], especially quartz, are only weakly soluble. Therefore, substantial volumes of water had to migrate through the lower Warsaw strata to precipitate the observed minerals. 6
This explanation depends upon the observation that rocks undergo changes after they are formed. Specifically, groundwater adds or removes minerals. This makes it impossible to know what minerals were in the rocks when they formed.
We used to think we knew how geodes formed. Apparently geologists aren’t certain anymore. If nobody knows how geodes formed, can we be sure we know how zircons formed?
“The most recent geologic research” indicates that the crystals in geodes were formed (at least in part) by precipitation rather than solidification. Although these two processes produce similar results, they do it differently.
Earlier in this article we referred to a simple experiment in which orange juice was partially frozen to demonstrate how different freezing points cause crystals to form. That experiment depended on changing temperature. Let’s try a different experiment at constant temperature to demonstrate precipitation.
Dissolve a few teaspoons of sugar in a clear plastic cup of water. Let that cup of water sit on a table for a week or so. As the water evaporates, the sugar solution becomes more concentrated. There comes a time when there isn’t enough water to dissolve all the sugar, so the sugar starts to precipitate (that is, un-dissolve). Eventually all the water evaporates, leaving just some nice, big sugar crystals in the cup.
You can do the same thing with salt instead of sugar. Now, here’s your science fair project. Try it with equal amounts of sugar and salt. How well separated are the crystals of sugar and salt? (Do they form nice, perfect layers; or are they mixed up?) Use a microscope to examine the crystals to see. (Salt crystals are square; sugar crystals are irregular.) What happens if you add a little bit of food coloring to the salt and sugar solution before it evaporates? Is the food coloring incorporated inside the crystals, or does it dry on their surfaces? Is the food coloring associated with one kind of crystal more than the other?
Rod’s email really raised two different issues, which we dealt with separately. First, you can’t tell what elements are found on Earth by looking at what elements are found on the moon, other planets, or stars—unless you make the unreasonable assumption that everything is made of the same mixture of things, in the same proportion, throughout the universe.
The second issue is that some radiometric dating techniques, potassium-argon dating of lava and uranium-lead dating of zircons, depend upon material that initially had no initial daughter material (argon or lead) to begin with. That just never happens in nature. Furthermore, these dating methods involve minute quantities of daughter material. Therefore, just an incredibly small initial amount of daughter material results in a very old, erroneous age.
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Disclosure, May 2008, “Timeless Isochrons”
2 Disclosure, May 2000, “Tim Thompson's Response”
3 Disclosure, May 2004, “Rock Formations”
6 Brian J. Witzke, “Geodes: A Look at Iowa's State Rock”, http://www.igsb.uiowa.edu/browse/geodes/geodes.htm