Question

How are the age of fossils calculated? Do you recollect the method of radioactive dating and the principles behind the procedure?

Answer 1

Age of fossils can be calculated by the following methods-
● Relative positions of the fossils in the sedimentary rocks- The bottom layers of the rocks are usually oldest and thus by finding a fossil there the approximate age can be determined.
● Radioactive carbon dating
● Radioactive carbon C-14 is formed when the cosmic rays of the sun act on nitrogen in the atmosphere.
● Apart from C-12 , C-14 is taken in by living forms through the food chain
● Once the organism dies it does not take any more carbon from the atmosphere.
● The radioactive carbon then decays at a known rate.
● The half life ( time required to reduce it to half its initial level) of C-14 is 5730 years.
● Measure the concentration of radioactive carbon in the fossil.
● Compare the concentration of C-14 with the radioactive activity of C-14 in living matter.
● If the radioactive content is 50% than the content in the living matter then the approx life of the fossil will be 5730 years(half life)