Carbon dating earth technique
These techniques are made possible by sensitive electronic instruments developed in the late twentieth century. A computer program for radiocarbon age calibration.
Both methods rely on the ongoing production of radiocarbon in the upper atmosphere.
Carbon-14 cannot be used to date biological artifacts of organisms that did not get their carbon dioxide from the air.
This rules out carbon dating for most aquatic organisms, because they often obtain at least some of their carbon from dissolved carbonate rock.
The ratios are consistent among species, and the slight (1-3%) differences can also be calculated from the ratio of C) decreases as the radiocarbon decays. Libby determined, one gram of pure carbon should produce about 14 (13.56) radioactive decays per minute.
The Beta-counting method detects the rate at which purified carbon decays. A rate of 7 decays/gram/minute would indicate an age of one half-life, or 5730 years old.
Carbon dating cannot be used on most fossils, not only because they are almost always allegedly too old, but also because they rarely contain the original carbon of the organism that has been fossilized.
Also, many fossils are contaminated with carbon from the environment during collection or preservation procedures.
Before the industrial revolution, from 1800 - 1400 AD, the natural production of radiocarbon was high, so dates are "too young." From 1400 AD to 300 BC they are "too old," and prior to 300 BC , they are too young.
The surplus "bomb" radiocarbon is just one of the effects human have had on the ratio of C.
During the industrial revolution (1850 - present) increasing amounts of fossil fuels were combusted.
3.5 decays/gram/minute of carbon would be produced by a sample 11,460 years old.
However, atmospheric testing of nuclear weapons in the late 1950's and early 1960's greatly increased the amount of radiocarbon in the atmosphere, so the decay rate of 14 decays per minute more than doubled.