Chapter 5 of the book of Genesis in the Bible/Torah is a goldmine of information. I can't speak for the accuracy of that information because it was before my time, but there's a great deal of it and hard numbers are provided. For Adam, the first man, and for all the generations of his descendants down to Noah, we are given the age at which each begat his eldest son, and the age at which each died. Ditto for the eldest son, lather, rinse, repeat. Armed with this information and a fearsome attention span, we can sit down with pencil and paper and determine exactly how many years after the Creation Noah lived. There's apparently enough similar data in the rest of the Bible that a patient theologian with a thorough knowledge of the history of the Middle East can go on chaining spans together right up until you hit events recorded outside the Bible. Once you've reached historical times, you can do some simple arithmetic and pinpoint the year in which the Creation took place.
This has actually been done, by Bishop James Ussher (1581-1656), Primate of All Ireland and Archbishop of Armagh. He concluded that the Creation had taken place on Sunday October 23, 4004 BC. (The Sabbath of the Old Testament is Saturday, and Jews have stuck with that to the present day).
In later years, Dr. John Lightfoot of Cambridge University was able by further calculation to identify the precise moment of Creation as 9:00 AM on the date Ussher established.
Having done all the groundwork, Ussher nailed down other dates of interest as well: The Fall from Eden happened on Monday November 10, 4004 BC. The Ark of Noah came to rest on Mt Ararat in modern Turkey on Wednesday May 5, 1491 BC -- a pleasant symmetry with Christopher Columbus' "discovery" of the "New World" in 1492.
Ussher's calculations were greeted with enthusiasm. His results were printed in an authorized version of the Bible in 1701, which is quite a coup.
Since those days, the precision of science has declined.
We're left wondering just why we bother at all, if none of these fancy-pants "intellectuals" has anything better to offer than round figures with nine zeroes on the end. What's with that, I ask you? Yes, oh, sure, it's trilobites all the way down, right?
Ussher's figures are not entirely consistent with currently known geological evidence (as of August 9, AD 2001): There seems to be a disparity in the neighborhood of several billion years, which may be due to a careless calibration error. Nevertheless, Ussher's work is accepted as valid by many fundamentalist Christians of the Young Earth Creationist persuasion.
- Craig, G. Y. and E. J. Jones, A Geological Miscellany. Princeton University Press, 1982.