Question

(a) What are fossils ?
(b) A child finds a fossil of a leaf . List and describe two ways to decide how long ago the leaf was part of a living tree.

Answer 1

Fossils are any preserved evidence of life from a past geological age in a rock or stone or soil.

Two ways to decide how long ago the leaf was part of a living tree are:

• Radiocarbon dating using C-14
• Geological method by comparing with other stones or rocks of same time.

Answer 2

Fossils are:

Explanation:

• (a) Remains of dead plants and animals that lived in the ancient past.

1. These get preserved by natural processes.
2. Examples: Impressions on sand or rocks, bones, teeth, horns, claws, shells.

• (b) Age of the fossils can be determined by:

1. Absolute or Radiocarbon Dating : Here the ratio of two isotopes of carbon, that is, C14 and C12 is determined. Carbon is contained in the fossil as it is a living material.
2. Relative Dating : The fossil is compared to another object whose  age is known.