Movement of the Earth s Crust: Formation of: Mountain s Plateau's and Dome s

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1 Movement of the Earth s Crust: Formation of: Mountain s Plateau's and Dome s

2 References Information taken from several places including Prentice Hall Earth d=28978 Mr. Myer 9 th grade earth science PowerPoints Prentice Hall Science Explorer Earth Text

3 What are the forces that cause mountains and valleys to grow and form?

4 All change begins with stress

5 Stress occurs at the crust Push & Pull

6 Deformation The breaking, tilting and folding of rocks due to pressure

7 Pushing and squeezing Pulling Apart, stretches the rock Sliding (parallel) to the rock Compression Tension Shear

8 San Andreas Fault Lateral Fault ~3 min

9 Stress Fracture = Cracks

10 The break or crack along which rocks move UP Fault DOWN SIDEWAYS

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12 Normal Fault/Reverse Tension and or compression causes rocks to move up or down in relation to each other

13 Thrust Fault Compression causes older rock to now lie on top of younger rock Lateral Fault Blocks of rocks move horizontally past each other San Andreas Fault formed in 1906 during an earthquake in San Francisco

14 Folded Volcanic Mountain Formation Fault Block Domes

15 Mountains Folded vs. Faulted Folded When stress is applied to the crust it bends but does not break Compression Faulted Enormous underground pressure forces a whole rock up breaking away from another Occurs along faults Valleys Tension rugged

16 What Determines if Rock Will Fault or Fold? Temperature Pressure warmer rock is more likely to fold increased pressure makes rock more likely to fold Type of Rock brittle rock is more likely to fault and ductile rock is more likely to fold Duration of Stress sudden stresses = faults slow, gradual stresses are = fold

17 What mountains are these?

18 Formation of Appalachian Mnts. During Pangea Africa collided with the East Coast of North America -Folded Mountains

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21 Rocky Mountains Based on what you learned already, where do most mountains form?

22 Rockies -Folded Mountains Pacific Ocean North American Plate Subduction

23 Rocky Mountains Watch this 5 minute clip

24 Sierra Nevada

25 Sierra Nevada Mountains Fault-Block mnts -upwelling of magma created initial mnts -the crust then stretched in an E-W direction creating Faults and the mnt. range Fault Block Mountains

26 Domes 1. Created by compression and uplifting of magma Typically magma does not break through the surface 2. Erosion cutting through a plateau may form a dome

27 Half Dome Old ancient exposed magma chamber Faulting that created the Sierra Nevada mnts forced the magma chamber up Glacial Erosion removed half of the rock

28 How do Domes Form? A dome is an uplifted area created by rising magma. After the magma cools, surrounding rock may erode away, leaving behind the dome. Half Dome Crystallized unerupted magma Glaciations and erosion 80 % dome

29 Devils Tower

30 Black Hills of South Dakota and Wyoming are Domes Does anyone know the National Monument found in these Black Hills?

31 Plateau Formation Flat land that rises above sea level Vertical Faulting, Fold, Rivers

32 Flat-topped fold- rocks are raised but remain flat (mountains tilt)

33 Vertical Folding (Colorado Plateau)- underlying regions of the inner earth become hot and then expand pushing up on the crust above it.

34 Years of lava spreading over areas, piling into sheets Columbia Plateau covering parts of Idaho, Washington, and Oregon

35 Isostasy The concept that earths crust is floating in gravitational balance upon material of the mantle Deposition and erosion causes land to rise and fall

36 Isostasy In order for continents to be higher they must also be thicker. Fig. 21.6

37 What would cause some countries to rise and some countries to sink? Scandinavia Rising! Netherland Sinking!

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40 Will the addition of millions of tons of sediment and mud added to the Gulf of Mexico cause the Gulf to be more shallow No, b/c as the sediments are added the crust on the bottom of the sea floor sinks, making a balancing act.

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42 And the highest place on earth is?

43 Asia India Tethys Sea No More!

44 Himalaya Facts Young folded mnts. Highest Mnt. In the world ½ the world s pop. live in the countries that surround the mnt. Summit is marine limestone Lots of earthquakes and volcanoes

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48 Andes Facts Longest mountain chain above ground Mnt. Peaks are volcanoes Earthquakes common Form from oceancontinent convergence Subduction of S. American plate

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50 Death valley

51 Normal Fault Formed when a block of rock between two fault slides down Rift Valley DD918EB3.aspx ~ 3 min

52 The Great Rift Valley East Africa Runs from SW Asia to SE Africa East African Rift Valley Continuous Trench 2700 mi in length

53 Interesting Home to the largest fresh water lakes in the world Great understanding how oceans formed worlds oldest fossils Magma upwells to the surface of earths crust forming new crust

54 Formation of the E. African Rift Mantle rises, heating the earth s crust causing it to expand & fracture Subsides (sinks) further into the ground volcanic activity flood basalts floods the crust through fracture s, not volcano s Crust stretches & thins in the middle, Crust on either side now becomes a mountain

55 Future- crust becomes thin enough to fall below sea level forming an ocean

56 How is this guy able to float without sinking?

57 What would cause large crystals of this sort to build up on the beach?

58 The Dead Sea Lowest Place in the WORLD!!! Float due to density of salt (buoyant) Plate tectonics pull the crust making it thin, thus parts of it sink causing the rift (Strike/Slip Fault) 35% salt Why so much salt? Only water coming in, no way out Hot temps = lots of evaporation

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62 Mid-Ocean Ridges

63 A mid-ocean ridge Underwater mountain system Forms between two plate tectonics A rift develops on the spine of the mountain Magma fills the rift pushing the plates apart

64 Iceland Mid-Atlantic Ridge above Sea level

65 Mid-Ocen Ridge 7000 mi long (one of the longest in the world) Hidden from view-----except where it overlies a hot spot, its under the Atlantic ocean Iceland- volcanic made island

66 Mid-Ocean Ridge leads to 1. continen tal drift theory 2. Ocean Formation

67 How does the Atlantic Ocean widen? Sea Floor Spreading

68 Sea-floor spreading clip Bill nye science clip- sea floor spreading

69 What is the deepest place on Earth?

70 Formation of Mariana Trench 1. Ocean to ocean subduction

71 Challenger Deep Still a mile of water above Mt. Everest!

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