Answer:
Law of Superposition
Step-by-step explanation:
According to the law of superposition, the sediments are usually deposited on top of one another, giving rise to the formation of sedimentary layers. In an undisturbed sedimentary sequence, the layers that are formed at the apical portion are the youngest and the layers that are found at the base are the oldest.
Thus, the concept of laying down of sediments on top of one another is the law of Superposition.