The changing ratio of C-12 to C-14 indicates the length of time since the tree stopped absorbing carbon, i.e., the time of its death.Obviously, if half the C-14 decays in 5,730 years, and half more decays in another 5,730 years, by ten half-lives (57,300 years) there would be essentially no C-14 left.
Because of the distortions and lies spread by fundamentalists about scientific dating there is a need for a centralized source of information on the topic.
A few examples of such lies are presented at the very bottom of this page.
Perhaps no concept in science is as misunderstood as "carbon dating." Almost everyone thinks carbon dating speaks of millions or billions of years.
But, carbon dating can't be used to date either rocks or fossils.
Dating is not necessary to demonstrate that evolution is a fact.
Chronological sequence is all that is really required.
Cross-dating is a technique used to take advantage of consistencies in stratigraphy between parts of a site or different sites, and objects or strata with a known relative chronology.
A specialized form of cross-dating, using animal and plant fossils, is known as biostratigraphy.
Thus, no one even considers using carbon dating for dates in this range.
In theory, it might be useful to archaeology, but not to geology or paleontology.
Since it would only take less than 50,000 years to reach equilibrium from a world with no C-14 at the start, this always seemed like a good assumption.