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Old 11-20-2012, 12:38   #306
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Originally Posted by ArtificialGrape View Post
So that brings me back to my earlier question, do you think that carbon-14 dating is used to date the earth?
Peace Warrior,
in the interest of time, since I'm trying to get out of town for the holiday, allow me to ask a question, make a point, and share a story from the "science is cool" archive.

The question...
How would atmospheric saturation of carbon-14 contaminate readings of meteorites that crash to earth and are dated to around 4.6 billion years old? Scientific citation please.

The point...
To answer my own question above, no, carbon-14 is not used to date the earth. It is only used to date samples to around 50,000 - 60,000 years.

The story from the "science is cool" archive...
Professor John Wells of Cornell University devised a clever study to use biology to validate radiometric dating. Wells was studying corals that radiometric dating showed to live about 380, million years ago.

Making use of the fact that tidal friction slows the earths rotation over time (length of day increases about 2 seconds every 100,000 years, although earth's orbit around the sun does not vary in duration), Wells calculated that 380 million years ago a year would have contained 396 days of 22 hours.

Cool, but now what? Well, corals produce both daily and annual growth rings. By counting the number of daily growth rings between annual growth rings Wells determined that the coral experienced 400 days per year which would have meant a 21.9 hour day -- only a fraction of a percent deviation from what was predicted by radiometric dating. Ta da! Science is cool.

Wells, J.W., 1963, Coral growth and geochronometry, Nature, v. 197, p. 948-950

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