Which principle determines the relative ages of different rock layers based on the presence of cutting features?

The principle that determines the relative ages of different rock layers based on the presence of cutting features is the Principle of Crosscutting Relationships. This principle states that if a geologic feature cuts through another feature, the feature that is cut is older than the feature that is doing the cutting. For instance, if an igneous intrusion cuts through sedimentary rock layers, it indicates that the sedimentary layers were in place first, and then the intrusion occurred afterward. This helps geologists establish a sequence of events in the geological history of an area, providing clarity on the ages of the rock layers relative to one another.

While the other principles have their own significance—like the Principle of Superposition, which focuses on the arrangement of rock layers and helps determine relative age based on their position, or the Law of Original Horizontality, which states that layers of sediment are originally deposited horizontally—none directly address the implications of features that cut through others as clearly as the Principle of Crosscutting Relationships does. The Unconformity principle relates to gaps in the geological record but does not specifically encompass the cutting relationships that define the ages based on observed features. Thus, the Principle of Crosscutting Relationships is essential for understanding how geological features interact over time