Relative Age Determination in Geology

Granite and Sandstone Relationship

The relationship between the granite and sandstone layers that were uncovered during the geological survey provides valuable insight into the relative ages of these rock formations. In this case, the granite was observed to underlie the sandstone, indicating a sequence of events in their formation.

Principle of Inclusions

From the discovery of pieces of sandstone contained within the granite, we can apply the principle of inclusions to determine which rock formation is younger. The principle of inclusions states that any rock containing fragments or inclusions of another rock must be younger than the fragments it contains. In this scenario, the granite must be younger than the sandstone since it encloses pieces of the pre-existing sandstone within its structure.

Principle of Cross-Cutting Relationships

Another geological principle that supports the conclusion of the granite being younger than the sandstone is the principle of cross-cutting relationships. This principle asserts that if one geological feature cuts through another, the cutting feature is considered younger. In this case, the granite layer is intruding into the sandstone layer, carrying along fragments of the sandstone within it. Therefore, based on the principle of cross-cutting relationships, the granite is the younger formation.

By applying these two fundamental principles of relative age determination in geology, it becomes evident that the granite discovered beneath the sandstone layer is younger in age. The presence of inclusions and the relationships between the rock formations provide valuable clues for understanding the sequence of events in the formation of these geological features.