What drives major geologic events?

• A. Solar radiation causing weathering.
• B. Movement of tectonic plates beneath Earth's surface.
• C. Magnetic field reversals every 100,000 years.
• D. Atmospheric pressure changes.

Answer: (B)

Major geologic events are driven by the slow, persistent movement of Earth's lithospheric plates. The heat from deep inside the planet sets up convection in the mantle, and the plates ride on these convective currents. Where plates interact—colliding, pulling apart, or sliding past each other—the result is earthquakes, volcanic activity, and mountain building. Subduction drags one plate into the mantle and can fuel volcanoes; spreading at mid-ocean ridges creates new crust; and collisions build features like mountain ranges. This plate tectonics process is what reshapes continents and oceans over millions of years.

Solar radiation primarily causes surface weathering and erosion rather than moving the solid crust on a large scale. Magnetic field reversals involve changes in the Earth's core magnetism and do not drive the mechanical shifts of plate boundaries. Atmospheric pressure changes affect weather on short timescales but don’t create the deep, long-term tectonic motions that produce major geologic events.