Relative dating and absolute dating of fossils

12 Dec

In historical geology, the primary methods of absolute dating involve using the radioactive decay of elements trapped in rocks or minerals, including isotope systems from very young (radiocarbon dating with Radiometric dating is based on the known and constant rate of decay of radioactive isotopes into their radiogenic daughter isotopes.Particular isotopes are suitable for different applications due to the type of atoms present in the mineral or other material and its approximate age.Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events.

In previous lessons, we talked about the Geologic Time Scale and how scientists use it to piece together the history of the earth.

For example, techniques based on isotopes with half lives in the thousands of years, such as Carbon-14, cannot be used to date materials that have ages on the order of billions of years, as the detectable amounts of the radioactive atoms and their decayed daughter isotopes will be too small to measure within the uncertainty of the instruments.

One of the most widely used and well-known absolute dating techniques is carbon-14 (or radiocarbon) dating, which is used to date organic remains.

The Wheeler Formation has been previously dated to approximately 507 million year old, so we know the trilobite is also about 507 million years old.

But, how can we determine how old a rock formation is, if it hasn’t previously been dated?