Layer T contains a well-known index fossil that is 120 million years old. Layer R contains a different index fossil that is 100 million years old. Based on this information and the principle of superposition, how old is Layer M?

Between 100 and 120 million years old

Explanation:

The principle of superposition refers to one of the geological principles used in the determining the relative depositional history or sequence of rock stratas in geologic stratigraphic study. The superposition principle explains that rocks deposited in stratas with the oldest rock layer being at the base and the youngest at the topmost layer. Hence using this principle, we can conclude that ; Rock layer M lies in between layer T and R ; thus M is younger than T and older than R. Therefore, the age of M will be between the range of age T and R.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .