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...
02:05
World in Motion: Earthquakes and Plate Tectonics
With the advent of plate tectonics, it's become apparent that episodes of extreme geologic upheaval--like earthquakes--are much more than simply random events.