Uranium lead dating meteorites

28 Oct

The paper is technical, so detailed evaluation of the contents should be left to geophysicists.

The following quotes give a sense of the kinds of problems Corfu discussed, and their implications.

For a man who does not believe in a miracle, a slow miracle would be just as incredible as a swift one."*G. Chesterton (1925)."The theory of evolution gives no answer to the important problem of the origin of life and presents only fallacious solutions to the problem of the nature of evolutive transformations . We are condemned to believe in evolution, but we will always search for a suggestion concerning the methods of transformations . Perhaps we are now in a worse position than in 1859 because we have searched for one century and we have the impression that the various hypotheses [of how evolution could have occurred] are now exhausted.

Presently, nature appears to be more steady, more firm and more refractory [resistant] to changes than we thoughtbefore we had made a clear distinction between hereditary variability [within species] and acquired characteristics [DNA characteristics fixing each species]. Salet, Hasard et Certitude: Le Transformisme devant la Biologie Actuelle (1973), p. Several methods for dating ancient materials have been developed.

Common lead is any lead from a rock or mineral that contains a large amount of lead and a small amount of the radioactive precursors of lead (i.e., the isotopes uranium-235, uranium-238, and thorium-232).

This figure is in good agreement with the age of meteorites and the age of the Moon as determined independently.

This will be covered in the chapters, Primitive Environment (chapter 9), and DNA (chapter 10).

An event is not any more intrinsically intelligible or unintelligible because of the pace at which it moves.Primordial lead is thought to have been formed by stellar nuclear reactions, released to space by supernovae explosions, and incorporated within the dust cloud that constituted the primordial solar system; the troilite (iron sulfide) phase of iron meteorites contains lead that approximates the primordial composition.The lead incorporated within the Earth has been evolving continuously from primordial lead and from the radioactive decay of uranium and thorium isotopes.The method has a dating range from 4.55 x 109 years ago to approximately 5 x 104 years ago, and takes advantage of the long decay chains of the radioactive parent atoms such as 238U, which spontaneously decays through 13 transitional stages until it reaches 206Pb, which is stable and is termed the daughter.238U has a half-life of 4.47 x 109 years; the transitional stages have an accumulated decay time of 0.0073% of the primary half-life permitting the parent-daughter comparison for chronometric purposes if a closed system with accompanying equilibrium conditions exists.