Final answer:
The deeper you excavate, the older the deposits is a principle in relative dating and stratigraphy, specifically using the law of superposition, principle of original horizontality, and principle of lateral continuity.
Step-by-step explanation:
The idea that the deeper you excavate, the older the deposits (in undisturbed contexts) makes use of several principles in relative dating and stratigraphy. One principle is the law of superposition, which states that in horizontal sedimentary rocks, the oldest layer is at the bottom and the youngest is at the top. Another principle is the principle of original horizontality, which says that sedimentary layers are originally deposited horizontally. Additionally, the principle of lateral continuity states that interruptions in sedimentary layers, such as rivers or canyons, occurred after the formation of the rock. These principles help archaeologists and geologists determine the relative ages of deposits based on their locations and depths of excavation.