Final answer:
The cause of plate tectonics, identified since the 1960s, is the movement of the Earth's lithosphere due to convection currents in the asthenosphere, leading to earthquakes, volcanic activity, and mountain formation.
Step-by-step explanation:
Since the 1960s, the cause of plate tectonics has been identified to be the movement of the Earth's lithosphere. This is due to convection currents in the underlying hotter, more fluid asthenosphere. The semi-liquid material in the asthenosphere rises, cools, and sinks, creating the forces that shift the Earth's plates. When these plates move apart, collide, or slide past each other, we observe this as earthquakes, volcanic activity, and mountain formation, all of which are part of plate tectonics.
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