1. The Principle of Superposition: This principle states that in undisturbed rock sequences, the oldest layers are found at the bottom and the youngest layers are found at the top. This principle is based on the simple idea that sediments are deposited in a chronological order, with the earliest layers forming first and subsequent layers accumulating on top of them.
2. The Principle of Original Horizontality: This principle states that sedimentary rocks are originally deposited in horizontal layers. While rocks may become tilted or folded due to tectonic activity, their original orientation was horizontal. This principle helps to understand the processes that have deformed the Earth's crust over time.
These two principles form the foundation of stratigraphy, the branch of geology that deals with the study of layered rocks and their chronological relationships.
