How Do We Know the Age of a Fossil?

Geologic Time, a competent introduction from the US Geological Survey.
BUT here are several slightly different time scales:
This means (in my mind at least) that there's no point memorizing exact numbers in millions of years for any particular geological boundary: they are going to change. What is important is to have the sequence in your head, together with a reasonable understanding of the approximate dates of the boundaries.

An activity to teach Relative Dating

"A Christian Perspective on Radiometric Method of Dating". Do not be put off by the title. This is a serious, noholdsbarred analysis of dating methods, which concludes that the methods are reliable and that the earth's age is well known and very old.
Return to Chapter 2 page
Page last revised June 7, 2004
Links checked September 30, 2005.