He was employed at Caltech's Division of Geological & Planetary Sciences at the time of writing the first edition.
He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.
However, human beings love to see factual precision, and we want to know how old something is.
For each dating or chronological method there is a link in the box at right to take you to that section of this page.
There, you will find a brief description of the method, plus links to take you to other webpages with more extensive information.
Dating is not necessary to demonstrate that evolution is a fact.
Chronological sequence is all that is really required.
Our understanding of the shape and pattern of the history of life depends on the accuracy of fossils and dating methods.
Some critics, particularly religious fundamentalists, argue that neither fossils nor dating can be trusted, and that their interpretations are better.
Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.
There are over forty such techniques, each using a different radioactive element or a different way of measuring them.
Rock art is a vital archaeological source to study and analyse the cognitive evolution of the human intellect across the world.
The importance of rock art and its dating has long been a key issue of rock-art research and continues to be attended by difficulties about methodology, misinterpretation of findings and overconfidence in the reliability or precision of result.
Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.