Use of radio isotopes in carbon dating
The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.This restriction extends to animals that consume seafood in their diet.
Its consistent rate of decay allows the age of an object to be determined by the proportion of carbon-14 to other carbon isotopes. Carbon-14 is also used as a radioactive tracer for medical tests.Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 would remain undecayed).The question should be whether or not carbon-14 can be used to date any artifacts at all? There are a few categories of artifacts that can be dated using carbon-14; however, they cannot be more 50,000 years old.When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age.Scientists now realize that production of carbon-14 has not been constant over the years, but has changed as the radiation from the sun has fluctuated.Carbon-14 dating relies on the following assumptions: It is known that the radiocarbon content of the atmosphere has varied in the past, so the initial activity of carbon-14 has NOT been a constant.
The following variations in carbon-14 activity have been noted: Calibration curves have been produced by comparing radiocarbon dates with other dating methods such as dendrochronology (a dating method using the tree's growth rings).
Carbon-based rocks, such as bitumen and tephra, can also be dated in this manner.
Carbon dating is most effective on material that predates the 1940s; this is due to above-ground nuclear tests increasing the amount of carbon-14 in the environment.
When a plant or animal dies it stops taking in carbon-14 and radioactive decay begins to decrease the amount of carbon-14 in the tissues.
The age of the plant or animal specimen containing carbon, such as wood, bones, plant remains, is determined by measuring the ratio of carbon-12 to carbon-14. Because of this relatively short half-life, carbon-14 can only be used to date specimens up to about 45,000 years old.
Continue Reading Carbon dating works by comparing the amount of carbon-14 in a sample to the amount of carbon-12.