What is plate tectonics?

What is plate tectonics?

• A. A model where Earth is a single undivided shell.
• B. The theory that continents drift due to ocean currents.
• C. The theory that Earth's lithosphere is divided into moving plates that float on the asthenosphere.
• D. The theory that earthquakes are caused by the Sun's gravity.

Answer: (C)

Plate tectonics is the idea that Earth’s outer shell is broken into moving slabs called tectonic plates that float on the partially melted layer beneath, the asthenosphere. These plates shift slowly because of convection currents in the mantle, and where they meet they can pull apart, collide, or slide past each other. This movement at plate boundaries explains why earthquakes happen, where volcanoes form, and how continents and oceans drift over time. The notion of a single undivided shell doesn’t account for these moving pieces, and saying continents drift because of ocean currents isn’t accurate—the driving force is the motion of the tectonic plates themselves. Earthquakes aren’t caused by the Sun’s gravity; they arise from stresses released as plates interact.

Plate tectonics is the idea that Earth’s outer shell is broken into moving slabs called tectonic plates that float on the partially melted layer beneath, the asthenosphere. These plates shift slowly because of convection currents in the mantle, and where they meet they can pull apart, collide, or slide past each other. This movement at plate boundaries explains why earthquakes happen, where volcanoes form, and how continents and oceans drift over time. The notion of a single undivided shell doesn’t account for these moving pieces, and saying continents drift because of ocean currents isn’t accurate—the driving force is the motion of the tectonic plates themselves. Earthquakes aren’t caused by the Sun’s gravity; they arise from stresses released as plates interact.