Question

Write the definition of fossils and explain the process of dating fossils.

Answer 1

Hint: The process of dating of fossils is mainly carried out by carbon dating. Carbon dating is used for identifying how old a fossil is. It helps in getting information about our ancestors.

Complete answer:
- Fossils are preserved remains or traces of once-living organisms from a past age. Fossils of animals and plants give us an idea of the previous life that existed on earth. Dating fossils is done for identifying how old a fossil is, and from this data, we can deduce which geological age the organism belonged to.
- Carbon dating is a radiometric dating method that is used for determining the age of a fossil using the presence and properties of radiocarbon (${ C }^{ 14 }$), which is a radioactive isotope of carbon. Carbon (${ C }^{ 12 }$) is a key element of all cells of our body and all the biomolecules derived from our food. ${ C }^{ 14 }$ is constantly created in the earth’s atmosphere due to the interaction of cosmic rays with the nitrogen present in the atmosphere. While ${ C }^{ 12 }$ is abundantly available, the ratio of ${ C }^{ 12 }$ to ${ C }^{ 14 }$ always remains constant, be it in the environment or in the molecules, cells, and tissues of the living organisms.
- This constant ratio is maintained until the organism dies when ${ C }^{ 14 }$ stops being replenished. Then, the overall amount of ${ C }^{ 14 }$ in the organism begins to decay exponentially.
- 5770 years is the half-life period of ${ C }^{ 14 }$.
- By knowing the amount of ${ C }^{ 14 }$ in fossil remains, you can determine how long ago the organism died by examining the departure of the observed ${ C }^{ 12 }$ to ${ C }^{ 14 }$ ratio from the expected and known ratio for a living organism.
- The half-life of an isotope is defined as the amount of time it takes to become half the initial amount of the radioactive isotope present.
- This technique can be used to date fossils only up to 50,000 years old. For fossils older than the time period, other special dating methods are used.

Note:
- Carbon dating is also known as radiocarbon dating or carbon-14 dating.
- There are various other forms of dating such as electron spin resonance dating. These types of dating come under Absolute Dating, which consists of various radiometric and non-radiometric dating methods.