Which term describes the regular rise and fall of the ocean's surface caused by the Moon's gravity?

• A. Tides
• B. Erosion
• C. Weathering
• D. Deposition

Answer: (A)

Tides describe the regular rise and fall of the ocean surface caused by the Moon's gravity. The Moon’s gravity pulls on Earth's oceans, creating a bulge on the side closest to the Moon and another on the opposite side due to inertia. As the Earth rotates, coastal areas move into and out of these bulges, producing high tides when aligned with a bulge and low tides when they are not. The Sun also influences tides, but its effect is smaller than the Moon’s for this phenomenon. The other terms refer to processes that change land and sediments (erosion, weathering, deposition) and do not describe the regular up-and-down motion of the ocean surface.