Question

Select the statement(s) that are accurate about plate tectonics and convection currents.


Convection currents in Earth's mantle cause Earth's plates to move.

Earth's plates move around on the upper mantle.

Molten rock cools as it nears Earth's crust and sinks back down toward the outer core.

Melted rock from the inner core moves toward Earth's crust because it is less dense.

Plate tectonics is the theory that Earth's surface is broken into large land masses that move.

Answer 1

Accurate:
- Convection currents in Earth's mantle cause Earth's plates to move. — True. Mantle convection is a major driver of plate motions (along with slab pull and ridge push).

- Earth's plates move around on the upper mantle. — True. The rigid lithospheric plates move over the weaker, partially ductile asthenosphere, which is part of the upper mantle.

Not accurate:
- Molten rock cools as it nears Earth's crust and sinks back down toward the outer core. — False/misleading. Cooler material near the surface can sink as part of mantle convection, but the mantle is mostly solid (not “molten rock”) and the sinking goes into the deeper mantle, not specifically “toward the outer core” in the literal sense.

- Melted rock from the inner core moves toward Earth's crust because it is less dense. — False. The inner core is solid metal (not “melted rock”), and mantle convection involves heated mantle material from the core–mantle boundary, not molten rock rising from the inner core.

- Plate tectonics is the theory that Earth's surface is broken into large land masses that move. — False/incomplete. Plate tectonics says the lithosphere is broken into plates (continental and oceanic) that move; it’s not limited to “large land masses” (continents).