Question

How are fossils formed? Describe, in brief, two methods of determining the age of fossils.

Answer 1

Fossils are defined as the remnants of past forms of life which get preserved in the rock sediments since past ages. Generally, with the death of any living organism, its body is decomposed by the action of decomposers but sometimes due to the conditions being unfavourable for the action of microorganisms these bodies do not decompose completely and get caught in the mud by the cover of wind and water. These sediments eventually get accumulated and hardened over a period of times and forms an impression which give rise to the formation of fossils.

Two methods of finding the age of fossils are:

a) Relative method- In this method, while digging the surface of the earth for finding fossils, the fossils which are found in upper layers of earth are more recent ones than those which exist in the deeper layers of earth.

b) Dating method- According to this method, the rate of decay of radioactive material is known and the ratio of the radioactive element and its decay products tells about how long the radioactive element was present in the rock. This is known as the half-life of that radioactive element which means the time taken for the decay of half of the sample. In carbon dating method carbon-14 is used to study the age of organic materials.