Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2004

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Claim CD013:

Source:

Response:

1. Argon may be incorporated with potassium at time of formation. This is a real problem, but it is easily overcome either by careful selection of the material being dated or by using ⁴⁰Ar/³⁹Ar dating instead of K-Ar dating.
   
   In the case of the claim about recent lava yielding dates that are millions to billions of years old, H. M. Morris (1974) misstated the facts concerning these "anomalous" dates as published in Funkhouser and Naughton (1968). The main misstatements of fact by Morris are as follows:
   
   
   • It was not the lava that was dated, but inclusions of olivine, called "xenoliths", present within the lava. These gave anomalously old age because they contained excess argon that the enclosing lava did not.
     
     
   • Morris failed to mention that the lava matrix without the xenoliths was dated and found to be too young to date using potassium-argon. (Funkhouser and Naughton [1968, 4603], stated that the matrix rock "can be said to contain no measurable radiogenic argon within experimental error.") This is consistent with the recent age of lavas and the state of the art of K-Ar dating at that time. The presence of excess argon was only a problem for the xenoliths but not for the lava containing them.
   
   Morris cited other examples of anomalous dates produced by excess argon and falsely claimed that it is a universal problem for K-Ar dating. The problem is not universal, as the majority of minerals and rocks dated by K-Ar do not contain the excess argon. Where excess argon is a problem, accurate, reliable dates typically can be obtained using ⁴⁰Ar/³⁹Ar dating, as demonstrated by Dalrymple (1969) and Renne et al. (1997) and discussed by Dalyrmple (2000).
   
   
2. Morris's complaints are dated in that, for the most part, geologists no longer use the K-Ar dating technique as was practiced in 1974. Instead, K-Ar dating has been largely replaced by the related ⁴⁰Ar/³⁹Ar dating technique. This change also solved other problems that Morris complained about in his discussion of the K-Ar dating technique. These complaints were as follows:
   
   
   1. Claim: K-Ar dating techniques must be calibrated by uranium-lead (U-Pb) dating.
      
      Response: Some calibrations between U-Pb and K-Ar were done in the 1940s and early 1950s, but the decay rates of all the different radioisotopes involved are now known to within 1 percent, making the different dating techniques independent.
      
      With ⁴⁰Ar/³⁹Ar dating, it is possible to calibrate this dating method by using volcanic deposits created in historic volcanic eruptions -- for example, the eruption of Mount Vesuvius on August 24, 79 C.E. (Renne et al. 1997). In addition, ⁴⁰Ar/³⁹Ar dating can be compared not only with U-Pb dating techniques but also with other absolute dating techniques -- for example, K-Ar, Rb-Sr, and Sm-Nd dating techniques -- which all provide dates consistent with each other and with associated ⁴⁰Ar/³⁹Ar dates. This has been demonstrated by the dating of chondrite meteorites (Dalrymple 1991) and tektites and other ejecta and deposits created by the giant meteorite impact at Chicxulub in the Yucatan Peninsula (Dalrymple et al. 1993).
      
      
   2. Claim: The potassium-argon is an open system.
      
      Response: The papers cited by Morris fail to probe this point. The first paper simply demonstrates that rock altered by weathering cannot be dated. This is a common-sense conclusion understood by geologists literate in the basics of their profession; it is irrelevant to the unaltered minerals that are typically dated using K-Ar, ⁴⁰Ar/³⁹Ar, and other techniques. The final paper claims potassium is quite mobile because potassium can be extracted from iron meteorites by using distilled water. However, K-Ar dating commonly uses potassium silicate minerals, which are very insoluble in water and resist weathering. Potassium cannot be significantly leached from the minerals used in K-Ar dating, or, conversely, the minerals from which significant potassium can be leached are not the minerals used in K-Ar dating.
      
      
   3. Claim: The decay rate of potassium is subject to change.
      
      Response: This is simply not true.
      
      
   4. Claim: Argon maybe incorporated with potassium at time of formation.
      
      Response: See first point (a) above.
      
      
   5. Claim: K-Ar ages are extremely variable.
      
      Response: As previously noted, K-Ar and ⁴⁰Ar/³⁹Ar dating both provide extremely consistent dates when the methods are used properly (Dalrymple 1991; 2000). The single paper (Engels 1971) cited by Morris clearly stated that variability resulted from presence of unwanted impurities in the specific mineral being dated. If the sample dated consisted of an absolutely pure mineral, there would not be any variability in the K-Ar dates obtained from them.

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