Dating rocks and fossils using radioisotopes
Fossils are collected along with rocks that occur from the same strata.
These samples are carefully cataloged and analyzed with a mass spectrometer.
Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating.
By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change.
The mass spectrometer is able to give information about the type and amount of isotopes found in the rock.
Scientists find the ratio of parent isotope to daughter isotope.
Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.
The half-life is 5730 years so it can be used to date samples between 1000 and 50,000-60,000 years old.Radiometric dating is also used to date archaeological materials, including ancient artifacts.Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.In K-40 dating the proportions of K-40 atoms to Ar-40 atoms is measured.
The half-life of K-40 is 1.26 billion years so it is useful for dating samples over 100,000- 1 million years old. The time it takes for the radioactivity to fall to half of its original level D.3.3 Deduce the approximate age of materials based on a simple decay curve for a radioisotope.
This is an opportunity to enter into the nature/nurture debate.