In stratigraphy, what does the term 'strata' refer to?

• A. Layers of sediment
• B. Fossils embedded in rock
• C. Layers of sediment that reveal geological history
• D. Earth's core

Answer: (C)

Strata are layers of sedimentary deposition that accumulate over time, forming a sequence. In stratigraphy, these layers provide a chronological record of Earth's past, with younger material typically over older material. This layered record is what allows scientists to read geological history—the environmental conditions, climate changes, and events that occurred as the layers formed. Fossils may be found within strata and help interpret the history, but the term itself refers to the layered units that collectively reveal that history. The other options point to components or unrelated ideas, while the essence of strata is the stacked layers that document geological history.