Final answer:
The principle stating that undistributed underlying geologic deposits are older than overlying deposits is known as the law of superposition, which is used in relative dating to determine the sequence of geological layers.
Step-by-step explanation:
The principle that undistributed underlying geologic deposits are older than overlying geologic deposits is called the law of superposition. This principle, one of several used for relative dating in geology, was developed by Nicolas Steno in the 17th century and it is fundamental to understanding the sequential order of Earth's geological layers. According to the law of superposition, in a sequence of undisturbed sedimentary rocks, the oldest layers will be on the bottom with successively younger rocks on top, which allows geologists to determine the relative ages of the rocks and the objects contained within them.