Mes Hutton and William Smith are credited for advancing the concept of geological time. Hutton concluded, after studying rocks of the Earth, that each layer represented a specific interval of geologic time. These rock layers are now referred to as . Smith discovered that certain rock layers contained fossils unlike fossils found in other layers. These fossils are used as a key to help identify and date particular layers of rock throughout the world.

unconformities, successive

Explanation:

William Smith and Mes Hutton are one of the few geologist who studied the evolution or date the age of earth by studying rocks and its formation. William Smith drew first few geological maps of the earth surface.

Hutton work was accessible by writing of Playfair. He said unconformities is the evidence of the succession of the world. The unconformities are found between the two layers of rocks at different angles. It represents a gap in time in the geological records. They represents the specific interval of the geological time.

Fossil succession principle states that life forms evolves in a specific time and the mechanism behind it is evolution. These are used to identify and date rocks.