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No. 71: Sep-Oct 1990

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Of time and the coral - and other things, too

R. Fairbanks is a paleooceanographer at the Lamont-Doherty Geological Observatory. Recently he has been drilling deeply into the submerged coral reefs off Barbados. During his research, it has been discovered that the radiocarbon (C1 4 ) scale is in serious error beyond 10,000 years BP. Radiocarbon dating is widely used in archeology, but it has always been hard to estimate how much radiocarbon was present in the earth's atmosphere thousands of years ago. As a matter of fact, even before Fairbanks' discovery, a major correction to the radiocarbon time scale was made using tree-ring counts as an absolute reference. But tree ring data go back to only about 10,000 years.

The latest correction was made by E. Bard, also at Lamont-Doherty, who took Fairbanks' coral cores and compared the radiocarbon dates with uranium-thorium dates. The result is that at 20,000 BP, the radiocarbon date is 16,500 BP, 3500 years too low. [Of course, all this as sumes that the uranium-thorium dates are accurate.] Use of the newly corrected radiocarbon scale has pushed the peak of the Ice Ages back from 18,000 BP to 21,000 BP.

But there is more. The same article in Science, without saying how he came up with the number, has Bard fixing the strength of the earth's magnetic field at only half its present level 20,000 years ago. This is most interest-ing because over the last 400 years of direct measurements, the geomagnetic field has been steadily decreasing! When and why was there a peak in the intensity of the geomagnetic field?

Back to Fairbanks, who also used his coral data to estimate changes in global sea level versus time. About 12,000 BP, he states, sea level was rising ten times faster than today due to melt water from the polar ice caps. This amounts to 2.5 to 4 meters per century. "...perhaps fast enough to prompt legends of a Great Flood"! (Kerr, Richard A.; "From One Coral Many Findings Blossom," Science, 248: 1314, 1990.)

Comment. It is exceedingly rare to find a scientist musing that there really might have been a Flood.

From Science Frontiers #71, SEP-OCT 1990. � 1990-2000 William R. Corliss