Chapter 1 earths surface
- 1. Chapter 1 Movement of the Earth’s Crust
- 3. Earth’s Changing Surfaces • Crust- is the surface, or outermost, layer of the Earth. • Two types – Continental crust • Makes up earths landmasses • About 32 kilometers thick in most places • Under mountains can be up to 72 kilometers thick
- 4. Two types continue • Oceanic crust – Found under the ocean floor – Usually about 8 kilometers thick
- 5. Stress on Crust • As the rocks of the crust undergo stress, they slowly change shape and volume. • Rocks will move up, down, or sideways – Movement causes the rocks to break, tilt, and fold
- 6. Deformation • Deformation- the breaking, tilting, and folding of rocks. • Three basic types – Compression- squeezes the rocks of the crust • This causes the rocks to move closer together • Makes the rocks denser and smaller in volume • Pushes the rock higher up and deeper down • Examples- trash compactor, squeezing clay in your hands
- 7. Basic types • Tension- pulls on the rocks of the crust, causing them to stretch out over time. – Rock under tension becomes thinner in the middle than at the ends. – Volume of the rock increases, its density decreases. – Examples- taffy being pulled, Silly Sutty being pulled between your fingers.
- 8. Basic types • Shearing- pushes rocks of the crust in two opposite directions. – Causes rocks to twist or tear apart – They bend or break apart – Examples- rubbing two pieces of limestone together
- 10. Faulting • Fault- a break or crack along which rocks move – Movements along a fault can be up, down, or sideways – Earthquakes often occur along faults – Hanging wall- the block of rock above the fault – Foot wall- the block of rock below the fault
- 11. Two types of Faults • Normal fault- if tension is acting on a fault, the hanging wall will move down relative to the footwall.
- 12. • Reverse fault- if compression is acting on a fault, the hanging wall will move up relative to the footwall. – Thrust fault- is formed when compression causes the hanging wall to slide over the foot wall. • usually mixes up the order of the layers in rock
- 13. Faulted Mountains and Valleys • Fault-block mountains- mountains formed by blocks of rocks uplifted by normal faults. • Rift valleys- valleys are formed when the block of land between two normal faults slides downward.
- 14. Folding • Fold- a bend in a rock ( like a rug sliding across the floor). • Two types of folds
- 15. Anticlines • Anticlines- the upward fold in a rock • This is how the Appalachian Mountains are formed • Is not always higher than the surrounding area • Anticlines can be under hills, valleys, or flat areas.
- 16. Syncline • Syncline- a downward fold in a rock
- 17. Difference between Fault or Fold • Four factors that determine if a rock will fold or fault. – Temperature – Pressure – Rock type – Stress
- 18. Plateaus • Plateaus- is a large area of flat land that is raised high above sea level
- 19. Domes • Domes- uplifted area created by rising magma • Is formed when fluid collects beneath the surface and pushes up on overlaying layers, forming a raised spot in the immediate area but leaving the surrounding regions flat and undisturbed.
- 20. Floating Crust • In the mantle the rock flows slowly (like molasses). Because the mantle is much denser than the crust, the solid, rocky crust floats on the mantle.
- 21. • The floating crust exerts a downward force on the mantle, and the mantle exerts an upward force on the crust. – Isostasy- the balancing of the downward force of the crust and the upward force of the mantle.
- 22. • Rising of landmasses – Examples- Norway, Sweden, and Finland have increased in elevation over a period of time. • Sinking of landmasses – Mississippi river has deposited millions of tons of mud and sand in the Gulf of Mexico and the water level has remained the same.