Comment: 12:56 - 13:54 (00:58)
Source: Annenberg/CPB Resources - Earth Revealed - 5. The Birth of a Theory
Keywords: "Harry H. Hess", "sea floor spreading", "mid-oceanic ridge", Earth, crust, trench, subduction, "Alfred Wegener", data, geopoetry, paleomagnetism
Our transcription: If mid-ocean ridges were continuously creating new sea floor, it would seem that the Earth must be growing, swelling along the ocean ridges like a ball slowly being inflated.
But scientists saw no convincing evidence for an expanding Earth.
How, then could the excess oceanic crust be explained?
Hess suggested that the ocean floor simply sinks back into the planet at deep marine trenches.
He claimed that this process, now called subduction, destroys the surface formed by sea floor spreading.
Just as Wegener's hypothesis was weakened by lack of data, so, too, was the model of sea floor spreading.
Hess cautiously referred to his own theory as "Geopoetry," but supporting evidence would come from the emerging field of paleomagnetism.
Geology School Keywords