The study of rocks strata is known as stratigraphy. It is useful and helps the scientist and the researcher to study the earth's crust and its past.
Scientist could age the rock using two methods. They are :
Relative ages
Absolute ages
Early scientist could determine the exact age of the rock of the earth's crust. They use to find the relative ages of the layers of the rocks and then determine how one rock layer is older or younger than the other. But with advancement and development of carbon dating, scientist could tell the exact age of the rocks found on the earth's crust.
The Scientists uses the relative as well as the absolute dating technique to date the rock layers. They organize the rock layers based on their age and scale from the oldest to the youngest on a geologic time scale. So an exact date of the rocks can be determine by using the two methods of relative age and the absolute age.
DNA (or deoxyribonucleic acid) is the molecule that carries the genetic information in all cellular forms of life and some viruses. It belongs to a class of molecules called the nucleic acids, which are polynucleotides - that is, long chains of nucleotides.
