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USGS CMG InfoBank: Pressure

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Comment: 05:00 - 05:51 (00:51)
Source: Annenberg/CPB Resources - Earth Revealed - 18. Metamorphic Rocks
Keywords: "Earth's surface", "directed stress", pressure, shear, fold

Our transcription: At the surface we are accustomed to the pressure of the air surrounding us.
We don't notice the air because the pressure is equal all over our bodies.
Deep underground, however, pressure is not equally applied.
Rock can be squeezed strongly with pressure greatest in the direction of the squeezing.
Sometimes opposing pressure can be applied on different parts of a rock causing it to bend or shear apart like a sliding deck of cards.
Whether from shearing or simple squeezing, the rock is experiencing what geologists refer to as "directed pressure" or "directed stress."
The structure of many metamorphic rocks is a result of directed pressure.

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