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Comment: 13:09 - 13:53 (00:44)
Source: Annenberg/CPB Resources - Earth Revealed - 18. Metamorphic Rocks
Keywords: "James Sadd", "metamorphic rock", magma, intrusion, "contact metamorphism", "convergent plate", "plate tectonics", "regional metamorphism", temperature, pressure
Our transcription: Most metamorphic rocks form in one of two geologic settings.
The first is where cold rock is intruded by a hot magma.
This is called "contact metamorphism", and its effects are confined to a small area.
The other setting is at a convergent plate margin where the motions of the plates generates metamorphic conditions over a wide area, in places covering thousands of square kilometers.
This is known as "regional metamorphism."
One of the main differences between contact and regional metamorphism is that temperature is the predominant cause of contact metamorphism; whereas regional metamorphism involves both temperature and pressure.
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