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Deformation of the Crust

Deformation of the Crust. Introduction. The earth’s surface is dynamic. The Himalayas, Rockies, Andes, and Grand Canyon are all visible reminders that the shape of the earth’s surface is always changing. These changes are all a result of the deformation of the earth’s crust. Deformation.

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Deformation of the Crust

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  1. Deformation of the Crust

  2. Introduction The earth’s surface is dynamic. The Himalayas, Rockies, Andes, and Grand Canyon are all visible reminders that the shape of the earth’s surface is always changing. These changes are all a result of the deformation of the earth’s crust.

  3. Deformation • The bending, tilting, and breaking of the earth’s crust. Plate tectonics is the major, but not only, cause of crustal deformation. • Two types of deformation: • Plastic – the bending/warping of crust. • Happens under high temperatures, pressures, and time. • Occurs deep under surface. • Brittle – the breaking of crust.

  4. Stress vs. Strain • Stress – force that causes pressure on rocks that make up the earth’s crust. • Stress increases with depth. • Stress causes deformation. • Strain – deforming strata (layers of rocks) by folding them or faulting (breaking) them

  5. Youngest Strata Oldest Strata Strata • All sedimentary rocks are originally deposited in flat (horizontal) layers called strata or beds. • Stress adds pressure to the strata • Strain deforms the strata

  6. Types of Stress • Compression – rocks are squeezed together. • Strata thickens • Pushes rocks either higher up or down in crust • Tension – pulls rocks apart • Makes rock layers thinner • Shearing – pushes rocks in opposite horizontal directions

  7. Stress + Plastic Deformation (strain) = Folding • Permanently deforming rocks because of plastic deformation causes the crust to fold. • Fold – wavelike structures in rock layers. • Most folds are a result of compression al strain

  8. Anticline – up folds in strata

  9. Syncline - down fold in strata

  10. Monocline – large step like fold

  11. Recumbant Fold – folds on top of itself

  12. Basin – radial down fold

  13. Dome – radial up fold

  14. Is this a dome or a basin? The oldest rocks are on the inside. The youngest rocks are on the outside

  15. Is there a dome or a basin under Michigan? THE ROCKS ON THE OUTSIDE ARE THE OLDEST, THE ROCKS ON THE INSIDE ARE THE NEWEST.

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