Which discipline focuses on the order of rock layers and their relative ages?

• A. Absorption
• B. Aphotic Zone
• C. Stratigraphy
• D. Adhesion

Answer: (C)

Stratigraphy is the study of how sedimentary rock layers are arranged and how their sequence reveals their relative ages. By reading the layers from bottom to top, we apply the idea that newer material typically sits above older material (the law of superposition). Other clues include that layers were laid down horizontally, so tilting or deformation reveals later events; anything that cuts across layers (like faults or igneous intrusions) is younger than the rocks it disrupts; and fragments included in a rock are older than the rock itself. This discipline is central to interpreting past environments in marine settings, such as sediment cores or layered shore deposits, helping us infer changes in sea level, sediment supply, or tectonics over time. The other terms describe unrelated ideas—absorption, a low-light ocean zone, and adhesion.