These isotopes have longer half-lives and so are found in greater abundance in older fossils.Some of these other isotopes include: back to the last global catastrophe (i.e.
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.Until this century, relative dating was the only technique for identifying the age of a truly ancient object.By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers.
Carbon-14 dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharaohs among other things. The half-life of carbon-14 is approximately 5,730 years. dinosaurs the evolution alleges lived millions of years ago.
Nuclear tests, nuclear reactors and the use of nuclear weapons have also changed the composition of radioisotopes in the air over the last few decades.
This human nuclear activity will make precise dating of fossils from our lifetime very difficult due to contamination of the normal radioisotope composition of the earth with addition artificially produced radioactive atoms.
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.
As stated previously, carbon dating cannot be used on artifacts over about 50,000 years old.