In geology, stratigraphy is used primarily to determine what?

• A. The color of rocks
• B. The age and arrangement of rock layers
• C. The mineral content of rocks
• D. The rate of erosion

Answer: (B)

Stratigraphy is about the order in which rock layers were deposited and their relative ages. By studying how layers are stacked and how they match up across different locations, you can determine which layers are older and how the sequence of deposition plays out over time. This focus on age and arrangement of rock layers is exactly what stratigraphy aims to uncover, allowing reconstruction of the geological history of an area. Colors and mineral content tell about rock composition, while the rate of erosion deals with landscape processes—neither directly addresses the sequence and timing of deposited layers.