So no fossils can be dated directly using U 238. Because of the huge differences in the half lives of Carbon 14 and Uranium238 they cannot be used together. Carbon 14 can only be used to date fossils of a very recent age. Uranium 238 can only be used to date volcanic rocks of a very old age.

Why is carbon-14 used in dating fossils and uranium 235 used to date rocks?

Another important atomic clock used for dating purposes is based on the radioactive decay of the isotope carbon-14, which has a half-life of 5,730 years. Carbon-14 is produced continuously in the Earths upper atmosphere as a result of the bombardment of nitrogen by neutrons from cosmic rays.

How can carbon-14 be used to determine the age of fossils?

Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food. Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.

How carbon-14 is used for dating the age of once living objects?

How is carbon-14 used to date fossils? All living things absorb carbon from the atmosphere, including an amount of radioactive carbon-14. When that plant or animal dies, it stops absorbing carbon. Scientists can measuring the amount of carbon-14 left over and estimate how long ago the plant or animal died.

What is carbon dating and uranium dating?

The key difference between carbon dating and uranium dating is that carbon dating uses radioactive isotopes of carbon, whereas uranium dating uses uranium, which is a radioactive chemical element. Carbon dating and uranium dating are two important methods of determining the age of different organic materials.