Question

Deeper layers of rock must be older than layers closer to the surface, this is the law of what?

Answer 1

superposition

Superposition refers to the position of rock layers and their relative ages   Figure below  . Relative age means age in comparison with other rocks, either younger or older. The relative ages of rocks are important for understanding Earths history. New rock layers are always deposited on top of existing rock layers. Therefore, deeper layers must be older than layers closer to the surface. This is the law of superposition.