The relative age of a rock is its age in comparison with other rocks. If you know the relative ages of two rock layers, you know which is older and which is younger, but you do not know how old the layers are in years.

What are the four eons of Earth history?

Evidence of Earths Past For example, the entire age of the earth is divided into four eons: the Hadean Eon, the Archean Eon, the Proterozoic Eon, and the Phanerozoic Eon. These four eons are further subdivided into eras (Table 7.3).

How old is granite?

Granite is the oldest igneous rock in the world, believed to have been formed as long as 300 million years ago. Granite is also whats called a “plutonic” rock, meaning that it forms deep underground. Granite is the main component that makes up the earths continental crust.