Validity of carbon 14 dating
Validity of carbon 14 dating
When objects of the Old Kingdom and Middle Kingdom of Egypt yielded carbon dates that appeared roughly comparable with the historical dates, Libby made his method known.
Kubler insisted that this heritage could not date from the 8th to 4th pre-Christian centuries, but rather was generated in the 4th to 8th century of the Christian era.
Therefore the claim was made that the magnetosphere around the earth, discovered in 1958, suffered occasional weakening, thus allowing more cosmic rays to pass it and to hit the nitrogen atoms in the upper atmosphere, changing them to radiocarbon.
It was further claimed that the magnetic field of the earth might have reversed its polarity in the last 40 thousand years, a phenomenon known to have happened in geological epochs.
And certainly the building of tree ladders, or carrying on the count from one tree to another may cause erroneous conclusions.
One and the same year may be dry in South California and wet in the northern part of the state.
In Worlds in Collision I claimed that the time since the last glaciation needs to be drastically shortened: the figure considered valid in 1950, the year Worlds in Collision was published, was still Lyells of 100 years earlier, namely 35 thousand years. previously this maximum advance had been assumed to date from about 25,000 years ago, actually 35,000 if one looks up the literature of the time. found that, as I also claimed, another advance of ice took place only 3,500 years ago.
Libby found (and I quote Frederick Johnson, who participated in his volume, Radiocarbon Dating) that the advance of the ice occurred about 1 1,000 years ago . A few years later Rubin and Suess of the Geological Survey of the U. The second confirmation came concerning the age of the petroleum. The surprising fact was that oil was found there in Recent sediment and must have been deposited during the last 9,200 years. (Emphasis added.) Actually I asked Libby whether he would see to it that petroleum should be subjected to tests and it was he who drew my attention to the work done by Smith.
If such reversals were not instantaneous but required thousands of years, the atmosphere during that time would not be shielded from cosmic rays and substantially more of them would reach it.
However, the scientific literature of the last few decades did not contain any reference to a reversal observed on human artifacts like pottery though a paper by Manley in 1949 (Science News, Penguin Publication) told of the work of G.
But as the method was refined, it started to show rather regular anomalies.
First, it was noticed that, when radiocarbon dated, wood grown in the 20th century appears more ancient than wood grown in the 19th century.
The method caught the fancy of the radiocarbon researchers.