Final answer:
Nicolas Steno found that the order of rock and fossil layers corresponds to different geologic time periods.
Step-by-step explanation:
The scientist who found that the order of rock and fossil layers corresponds to different geologic time periods is Nicolas Steno. He proposed the law of superposition, which states that the oldest rock layer is at the bottom and the youngest is at the top.
This law allows geologists to determine the relative ages of rocks and fossils by looking at their positions within the rock layers.