1. The Principle of Superposition: This principle states that in undisturbed rock sequences, the oldest layers will be found at the bottom, and the youngest layers will be found at the top. This is based on the idea that layers of sediment are deposited horizontally, and newer layers are deposited on top of older ones.
2. The Principle of Original Horizontality: This principle states that sedimentary layers are originally deposited horizontally. Any tilting or folding of these layers occurred after their deposition. This helps geologists understand the forces that have acted on the Earth's crust over time.
These principles laid the groundwork for modern stratigraphy, the study of layered rocks.
