Isaac Asimov describes uranium-lead geochronology

Cleaning out some old filing cabinets here at work, I found some old newspaper clippings of a science article by Science Fiction and popular science writer Isaac Asimov, describing uranium-lead geochronology of zircon.

As it turns out, the article still exists in the on-line archive of the LA times.  It can be found here.  Although the article is 22 years old, neither the fundamental physics, nor the billion-year-old rocks, have changed much during that time.  So it is still a useful reference for anyone wanting to know the basics of uranium-lead geochronology, and early earth history.