Principle of Original Horizontality

The Principle of Original Horizontality states that sedimentary layers of rock are originally deposited more or less horizontally or parallel to the Earth's surface. This means when we see rocks tilted or folded, it indicates they have been moved after their formation. This concept helps geologists determine the relative ages of rock layers and understand geological events, as any tilting or folding happened after the layers were initially laid down. Essentially, it provides a baseline assumption about how sedimentary layers form and helps scientists interpret Earth's geological history accurately.