Hess proposes sea-floor spreading 1960. Photo: Harry Hess argues that the continents had once been one, and have drifted apart. With the discovery of plate tectonics and the mapping of the earth ...

Hess proposes sea-floor spreading 1960. Photo: Harry Hess argues that the continents had once been one, and have drifted apart. With the discovery of plate tectonics and the mapping of the earth into ...

Of central concern are the plumes of sediment that mining would create, both at the seafloor and at depths around 1,000 meters, which have “some of the clearest ocean waters,” said Jeffrey ...