Comment: 24:36 - 25:14 (00:38)
Source: Annenberg/CPB Resources - Earth Revealed - 7. Mountain Building
Keywords: mountain, continent, mantle, erosion, orogeny, isostasy, "plate tectonics", gravity
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Our transcription: Mountain ranges, newly forming and ancient, mark the growth of continents in response to plate movements.
Floating on Earth's plastic mantle, these gigantic topographic features disappear slowly as their low-density roots are buoyed up.
So mountains owe their existence to two factors: the heat that drives plate tectonics and the effects of gravity.
In time, mountains wear flat, adding new crust to the cratons, the oldest, most stable lands on the planet Earth.
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Geology School Keywords
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