Sedimentary rock age dating
Fossils, however, form in sedimentary rock -- sediment quickly covers a dinosaur's body, and the sediment and the bones gradually turn into rock.
But this sediment doesn't typically include the necessary isotopes in measurable amounts.
Since the moon and the Earth probably formed at the same time, this supports the current idea of the Earth's age.
You can learn more about fossils, dinosaurs, radiometric dating and related topics by reading through the links below.
Fossils are generally found in sedimentary rock not igneous rock.
Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.
To determine the ages of these specimens, scientists need an isotope with a very long half-life.
Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.
In addition, the oldest known moon rocks are 4.5 billion years old.Unfortunately, these elements don't exist in dinosaur fossils themselves.Each of them typically exists in igneous rock, or rock made from cooled magma.So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.