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Deforming the earth’s crust Ch. 4, sec. 4

Deforming the earth’s crust Ch. 4, sec. 4. Mrs. Laubscher’s class. Are You Stressed Out?. Deformation The process by which the shape of a rock changes because of stress is called deformation . Types of Deformation Forces. Compression – objects squeezed together

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Deforming the earth’s crust Ch. 4, sec. 4

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  1. Deforming the earth’s crust Ch. 4, sec. 4 Mrs. Laubscher’s class

  2. Are You Stressed Out? Deformation • The process by which the shape of a rock changes because of stress is called deformation.

  3. Types of Deformation Forces • Compression – objects squeezed together Happens at convergent boundaries • Tension – objects stretched apart Happens at divergent boundaries • Shearing - objects rubbed together Happens at transform boundaries

  4. Folding (bending, buckling & folding) • The bending of rock layers because of stress in the Earth’s crust is called folding.

  5. Types of Folds • Anticlines = upward-arching folds • Synclines =downward, troughlike folds • Monocline= rock layers are folded so that both ends of the fold are horizontal. Imagine taking a stack of paper and laying it on a table. Think of the sheets of paper as different rock layers. Now put a book under one end of the stack. You can see that both ends of the sheets are horizontal, but all of the sheets are bent in the middle. monocline

  6. Folds can be . . . Medium sized AND . . . Small wrinkles

  7. Large mountain sized

  8. Which is which?

  9. Faults • Fault – surface along which rocks break and slide past each other • Footwall • Hanging wall

  10. Types of Faults Normal fault – • hanging wall slides down • caused by tension • at divergent boundaries

  11. Types of Faults Reverse fault • Hanging wall moves UP • Caused by compression force • At convergent boundaries

  12. Types of Faults Strike Slip Fault • Rocks move horizontally • Due to shearing force • Happens at transform boundaries

  13. Types of Mountains Folded mountains • Caused by rock layers being squeezed together, rounded hills Ex. Appalachian Mountains – happened when N. A. and African plates collided. Ex. Alps, Ural Mountains in Russia, Himalayas

  14. Types of Mountains Fault Block Mountains • Caused by tension • At divergent boundaries • Sharp jagged peaks Ex. Grand Tetons, Sierra Nevada mountains

  15. Types of Mountains Volcanic Mountains • Happens at subduction zones when at convergent boundaries when the oceanic plate sinks under another oceanic or continental plate. • Made out of magma that has been pushed up. • Many become islands • Most found in the Ring of Fire in the Pacific Ocean

  16. Other related words . . . • Uplift – rising of regions of earth’s crust to higher elevation • Rebound – crust slowly springs back to where it was • Subsidence – the sinking of regions of the earth’s crust to lower elevations

  17. Other related words . . . • Rift zone – set of deep cracks that forms between 2 tectonic plates that are pulling away from each other.

  18. Other related words . . . Sillsare ahorizontallayers of igneous intrusions. They are sheets of rock that are parallel to pre-existing rocks Dikes are vertical igneous intrusions. They are sheets of rock that are perpendicular to pre-existing rocks.

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