The remains or the preserved traces of living organisms of geological past are called fossils.
- When organisms die, their dead bodies decompose and get lost.
- But some parts of the body may be in the environment that does not let it decompose.
For example, dead insect will not decompose in hot mud, it will retain the impression of the insect body parts and thus preserved as fossils.
The age of fossils can be determined by two ways:
- If we dig into the earth and start finding fossils, it can be assume that the fossils closer to the surface are more recent to those found in deeper layers.
- By detecting the ratios of different isotopes of the same element in the fossil material.
