Answer:
Three principles that today are known as the "Steno Principles"
Step-by-step explanation:
Nicholas Steno proposed three principles that today are known as the "Steno Principles".
The first: Overlay. there are layers of sediments so that the lower one was deposited first, and the upper one the last.
The second: Original horizontality. No matter what the current orientation of a stratum is, it was originally created by a horizontal water tank. That then could have moved.
The third: Lateral continuity. Water deposits sediments in a continuous layer that ends only at the edge of its basin. Therefore, layers of rocks corresponding to both sides of a valley were originally a single layer.