How do mantle convection currents relate to plate motion?

How do mantle convection currents relate to plate motion?

• A. They create drag and push/pull plates, causing their movement.
• B. They have no effect on plate motion.
• C. They cause plates to dissolve.
• D. They only affect surface weather.

Answer: (A)

Mantle convection currents drive plate motion by creating drag at the base of the tectonic plates. Heat from Earth’s interior causes mantle rock to rise in upwellings and sink in downwellings. This circulating motion pushes and pulls on the rigid lithosphere floating above, causing the plates to move slowly. At upwelling zones, the rising mantle helps push plates apart and form new crust at mid-ocean ridges, while sinking slabs at subduction zones pull the rest of the plate along. So the convection in the mantle is the engine that moves the plates. The other ideas don’t fit because convection currents lie beneath the plates and directly influence their motion, not surface weather, and they don’t dissolve crust. They also do not have no effect—their whole purpose is to drive plate movement through drag and slab pull.

Mantle convection currents drive plate motion by creating drag at the base of the tectonic plates. Heat from Earth’s interior causes mantle rock to rise in upwellings and sink in downwellings. This circulating motion pushes and pulls on the rigid lithosphere floating above, causing the plates to move slowly. At upwelling zones, the rising mantle helps push plates apart and form new crust at mid-ocean ridges, while sinking slabs at subduction zones pull the rest of the plate along. So the convection in the mantle is the engine that moves the plates.

The other ideas don’t fit because convection currents lie beneath the plates and directly influence their motion, not surface weather, and they don’t dissolve crust. They also do not have no effect—their whole purpose is to drive plate movement through drag and slab pull.