Step-by-step explanation:
The principle of superposition states that "in an undisturbed sequence of strata, the oldest is usually at the bottom and the youngest on top of it".
Judging by this, we know that sedimentary rocks are arranged on top of one another. We can use this to determine relative age because we know for sure the oldest layers are at the base of the sequence and the youngest are on top.
ii. Stratigraphy deals with the relative way in which strata are deposited in sedimentary basins.
It is useful in determining age of rocks because, rocks in different localities can be correlated using stratigraphic principles.