What instrument is used to obtain long, continuous sediment cores from the seabed?

• A. Pelagic Sediment
• B. Sand
• C. Nodule
• D. Piston Corer

Answer: (D)

Obtaining long, continuous sediment records from the seabed requires a tool designed to drive into the sediment without breaking the continuity of the layers. A piston corer achieves this by using a piston inside the core barrel that moves with the core as it is pushed down. This mechanism reduces friction and suction, helping the core slide out smoothly and stay intact, so a long, undisturbed sequence of sediment is captured. This is essential for reconstructing past conditions from the sediment layers. The other terms describe seabed materials rather than tools for sampling—pelagic sediment, sand, and nodules are types of material you might find in or on the seafloor, not instruments. While other coring methods exist, piston corers are specifically designed to maximize core length and continuity, making them ideal for long sediment sequences.