Browse Search Feedback Other Links Home Home The Talk.Origins Archive: Exploring the Creation/Evolution Controversy

Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2004
Previous Claim: CD013.1   |   List of Claims   |   Next Claim: CD014.1

Claim CD014:

Isochron dating is unreliable. The method assumes that the samples are cogenetic, that is, that they form at the same time from a reasonably homogeneous common pool. This assumption is invalid. In particular, mixing two sources with different isotopic compositions gives meaningless but apparently valid isochron plots.

Source:

Overn, William, n.d. Isochron rock dating is fatally flawed. http://www.tccsa.tc/articles/isochrons2.html

Response:

  1. Mixing can usually be detected by plotting the total daughter isotopes against the ratio of daughter isotopes. These would not likely fall on a straight line if mixing occurred.

  2. Isochron plots from mixing can have any slope, even negative slopes. If mixing were common, we would expect a high percentage of isochron results to show negative slopes. They do not.

  3. Other factors can produce false isochrons (Stassen 1998; Zheng 1989). For example:
  4. False isochrons can usually be avoided by choosing appropriate samples. The samples must come from an (apparently) initially homogeneous source and avoiding obvious signs of weathering and metamorphism.

Links:

Stassen, Chris, 1998. Isochron dating. http://www.talkorigins.org/faqs/isochron-dating.html

References:

  1. Stassen, C., 1998. (see above)
  2. Zheng, Y.-F., 1989. Influences of the nature of the initial Rb-Sr system on isochron validity. In Chemical Geology (Isotope Geoscience Section) 80, pp. 1-16.

Further Reading:

Dalrymple, G. Brent, 1991. The Age of the Earth. Stanford, CA: Stanford University Press

Faure, Gunter, 1986. Principles of Isotope Geology, 2nd ed. New York: John Wiley and Sons.
Previous Claim: CD013.1   |   List of Claims   |   Next Claim: CD014.1

created 2003-8-4