Final answer:
The law being referred to in this question is the law of superposition, which states that fossils in sedimentary rock strata succeed each other vertically in a specific, reliable order.
Step-by-step explanation:
The law being referred to in this question is the law of superposition, which is a principle used in paleontology and stratigraphy.
The law of superposition states that in horizontal layers of sedimentary rock, the oldest rock layer is found at the bottom, and the youngest layer is at the top. This means that fossils in sedimentary rock strata succeed each other vertically in a specific, reliable order.