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Forces In The Earths Crust

Forces In The Earths Crust. Crust: the thin outermost layer of the earth. Continental crust is relatively thick and mostly very old. Oceanic crust is relatively thin and is always geologically very young. Forces In The Earths Crust. Forces In The Earths Crust.

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Forces In The Earths Crust

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  1. Forces In The Earths Crust Crust: the thin outermost layer of the earth. Continental crust is relatively thick and mostly very old. Oceanic crust is relatively thin and is always geologically very young.

  2. Forces In The Earths Crust

  3. Forces In The Earths Crust The continents we live on are parts of moving plates. Most of the action takes place where plates meet. Plates may collide, pull apart, or scrape past each other.

  4. Forces In The Earths Crust The plates are technically called lithospheric plates.

  5. Forces In The Earths Crust • Lithospheric Plates: • Move very slowly 10-20 cm per year • Stress and strain produced by moving plates builds up in the Earth's rocky crust, resulting in tremendous forces.

  6. Forces In The Earths Crust Types of Forces: Tension force- a force that tends to pull material apart Compression force- a force that tends to push material together Shear force- a force that tends to make two masses of material slide past each other

  7. Forces In The Earths Crust • Forces can cause the rocks in the the earths crust to: • Fold • Fracture (break) • Slip along the fracture surfaces

  8. Forces In The Earths Crust Fault: a fracture surface along which rock slips

  9. Forces In The Earths Crust • Basic Types of Faults • Normal faults • Reverse faults • Strike-slip fault

  10. Forces In The Earths Crust • Normal Fault • Formed by tension forces • Rock above the fault plane slides down, relative to the rock below the fault plane

  11. Forces In The Earths Crust • Reverse Fault • Formed by compression forces • Rock above the fault plane slides upward, relative to the rock below the fault plane

  12. Forces In The Earths Crust • Strike-Slip Fault • Formed by horizontal shear forces • Rock on either side of the fault plane slides past each other horizontally

  13. Forces In The Earths Crust • Hanging Wall & Foot Wall • Foot Wall: in this picture, the block farthest to the right (shaped like a foot) • Hanging Wall: the block on the other side, resting or hanging on the footwall

  14. Forces In The Earths Crust • Fault Scarp: • The fault has ruptured the Earth surface • Fault-generated cliff is called a fault scarp

  15. Forces In The Earths Crust • Credits • United States Geological Survey • http://geology.wr.usgs.gov/docs/parks/deform/gfaults.html • Earth Comm- 5 Unit Edition • Activity #5 Structural Geology and Your Community

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