02:37
Isostasy
Geophysicist and geologist Tanya Atwater discusses isostasy, which allows objects at the surface of Earth to float in equilibrium, and talks about how it helps define Earth's topography.
02:53
Making the Pieces Fit: Birth of a Theory: Plate Tectonics
Canadian geophysicist John Tuzo Wilson argued that Earth's outer layer consists of about a dozen separate plates, which float on the partially melted asthenosphere below them. His ideas paved the way for the integration of seafloor spreading and con...
05:54
World in Motion: Heat, Convection and Plate Tectonics
Most scientists believe heat and convection probably play a major role in plate tectonics. And, yet, many questions remain.