The extreme temperatures of the magma would just destroy the bones.So to determine the age of sedimentary rock layers, researchers first have to find neighboring layers of Earth that include igneous rock, such as volcanic ash.These layers are like bookends -- they give a beginning and an end to the period of time when the sedimentary rock formed.By using radiometric dating to determine the age of igneous brackets, researchers can accurately determine the age of the sedimentary layers between them.Scientists can determine how long ago an organism died by measuring how much carbon-14 is left relative to the carbon-12.Carbon-14 has a half life of 5730 years, meaning that 5730 years after an organism dies, half of its carbon-14 atoms have decayed to nitrogen atoms.You can learn more about fossils, dinosaurs, radiometric dating and related topics by reading through the links on the next page.Radiometric dating isn't the only method of determining the age of rocks.
Fossils can't form in the igneous rock that usually does contain the isotopes.
For example, by using a laser, researchers can measure parent and daughter atoms in extremely small amounts of matter, making it possible to determine the age of very small samples [source: New Scientist].
Geologists do not use carbon-based radiometric dating to determine the age of rocks.
The most widely known form of radiometric dating is carbon-14 dating.
This is what archaeologists use to determine the age of human-made artifacts. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old.
In addition, the oldest known moon rocks are 4.5 billion years old.