Question

The best way of dating fossils of recent origin is by
A. Radiocarbon method
B. Uranium lead method
C. Potassium argon method
D. A combination of all the above

Answer 1

Hint: Fossils are remains of previously living organisms from any geological era. The remains are naturally preserved. Fossils are generally exoskeletons, bones, shells, imprints on rocks, etc. Age of fossils can be estimated by radioisotope dating techniques.

Complete step by step answer: Chronological dating is the process by which any object is attributed to a date in the past. Radiometric dating is the process by which objects are dated according to the presence of radioactive material in trace amounts. The radioactive materials are believed to be incorporated when the objects were formed. In this method, the concentration of the natural isotope of the radioactive material is compared to the concentration of its decay products. The rate of decay of the material is constant and previously known.
Radioactive dating was first published by Bertram Boltwood. This process, at present, is the primary source of information for determining the age of rocks, fossils and even the age of the earth.
At present the three most common methods followed for radiometric dating are as follows:
Uranium Lead method: This method utilizes two isotopes of Uranium – U235 and U238. While using this method, we can find out the age of samples by two clocks – one is based on the decay of U-235 to Lead 207 and the other one based on the decay of U-238 to Lead 206. The half life of the first clock is about 700 million years, and that of the second clock is 4.5 billion years.
Radiocarbon dating: This method uses the C-14 isotope of carbon. Its half life is around 5,730 years. C-14 is continuously formed in the atmosphere by collisions of nitrogen. life forms on the earth acquires carbon throughout its life – plants from photosynthesis and animals by consumption of plants. after death, the C-14 decays with its half-life. When the remains of the organism are examined, the concentration of C-14 in it indicates the amount of time passed since its death. Since the half life of C-14 is less than other isotopes, this method can be used to date fossils of recent origin.
Potassium Argon method: This method is based on the decay of Potassium-40 to Argon-40. Since the half-life of Potassium is 1.3 billion years, this method is used to determine the age of the earliest of fossils.
Therefore, it can be concluded the Radiocarbon dating is used to date recent fossils.
Hence, option (a) is correct.

Note: Fossils are remains of animals or plants from a previous geological time scale. Fossils are important for studies of evolution. The age of fossils can be determined by radiometric dating procedures. The most common technique used is radiocarbon dating.