What term describes periodic short-term change in the ocean surface height at a location, caused by gravitational force and inertia?

• A. Tidal Datum
• B. Tidal Wave
• C. Calcareous ooze
• D. Tide

Answer: (D)

Tides describe the periodic change in ocean surface height at a location caused by gravity and inertia. The Moon and Sun pull on the oceans, creating bulges on the side of Earth closest to them and, due to inertia, a second bulge on the far side. As Earth rotates, a coastal area moves into these bulges and out again, producing high tides when aligned with a bulge and low tides in between. This cycle repeats roughly every day and a half, giving two high and two low tides in many locations, though the exact timing and height vary with lunar phase and local geography. The correct term for this phenomenon is tide. A tidal datum is only a reference level used for measuring tides; tidal wave is not the standard term for tides (and is often misused for tsunamis); calcareous ooze is a sediment type and not related to changes in sea level.