Which combination of factors creates ocean layering?

• A. Temperature alone
• B. Salinity alone
• C. Both temperature and salinity
• D. Neither temperature nor salinity affects layering

Answer: (C)

Ocean layering is about how density changes with depth. Water density is controlled by both temperature and salinity: cooler water is denser, and saltier water is denser. If only temperature changes with depth, you still get a density difference and a layered structure, but when both temperature and salinity vary with depth, their combined effect often creates a stronger and clearer set of layers. This is why areas of the ocean show distinct layers like a cooler, saltier deeper water sitting beneath a warmer, less salty surface layer. In short, density stratification—the driver of layering—depends on both factors, so both temperature and salinity together create the layering.