Which of the following is primarily responsible for the large-scale movement of continents over long periods of time?

• A. Shifting of tectonic plates
• B. Erosion by wind
• C. Ocean currents
• D. Volcanic eruptions

Answer: (A)

Shifting of tectonic plates is the force that moves continents over long periods. The Earth's lithosphere is broken into large and small plates that float on the partially melted mantle beneath. Heat-driven convection in the mantle slowly pushes and drags these plates, causing them to pull apart, collide, or slide past one another. Over millions of years, this plate movement reorganizes the positions of landmasses, forming and breaking apart continents and supercontinents. Erosion by wind, ocean currents, and volcanic activity change landscapes locally and climate, but they don’t drive the whole-planet repositioning of continents.