Approximately 300 million years ago, Pangaea, shown in the illustration below, was formed.
One hundred million years later, this supercontinent began to break up and move apart. Not until
about 30 years ago did scientists understand why this movement occurred. The theory of plate
tectonics was supported by many scientists because it answered the questions they had about the
connections between plate tectonics, earthquakes and volcanoes. How does the theory of plate
tectonics describe the movement of tectonic plates?
A. The plates float along ocean waves.
B. The plates are pulled toward cooler areas.
C. The plates are lifted by the eruption of volcanoes.
D. The plates are moved by heated material in the Earth