The dynamic crust
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The dynamic crust Presentation Transcript

  • 1. The Dynamic CrustThe Dynamic Crust
  • 2. The Dynamic CrustThe Dynamic Crust I.I. Evidence of Crustal Changes –Evidence of Crustal Changes – or HOW do we knowor HOW do we know that movement of rocks takes place on Earth?that movement of rocks takes place on Earth? A. Deformed Rock Structure - Sedimentary strataA. Deformed Rock Structure - Sedimentary strata normally form in anormally form in a horizontalhorizontal position. Any change. Any change from the horizontal position is evidence offrom the horizontal position is evidence of minorminor crustal changecrustal change
  • 3. 1.1. FoldedFolded StrataStrata
  • 4. 2.2. TiltedTilted StrataStrata
  • 5. 3.3. FaultedFaulted StrataStrata
  • 6. B. Fossil EvidenceB. Fossil Evidence 1. Marine fossils found at high elevations suggest uplift.
  • 7. 2. Subsidence/sinking2. Subsidence/sinking 2. Shallow water marine fossil found at great ocean depths suggest subsidence/sinking.
  • 8. II. Plate TectonicsII. Plate Tectonics
  • 9. II. Plate TectonicsII. Plate Tectonics 1. Crust 5 – 35 km thick Density 2.7 – 3.0 g/cc 2. Mantle 2,900 km thick Density 3.3 – 5.5 g/cc 3. Outer Core 2,250 km thick Density 9.9 – 12.1 g/cc 4. Inner Core 1,220 km thick Density 12.7 – 13.0 g/cc
  • 10.  The crust contains bothThe crust contains both oceanic crustoceanic crust which iswhich is covered by our oceanscovered by our oceans andand continental crustcontinental crust,, that is the land on whichthat is the land on which we live.we live.
  • 11. 2. Earth’s Surface2. Earth’s Surface 5 4. Upper Mantle 2 . 1. OceanLabel your diagram 6. Lithosphere 3. Oceanic Crust
  • 12. b. Density of:b. Density of: 1.1. Ocean (water)Ocean (water) 1.0 g/ml1.0 g/ml 2.2. Granite (continental crust)Granite (continental crust) 2.7 g/ml2.7 g/ml 3.3. Basalt (ocean crust)Basalt (ocean crust) 3.0 g/ml3.0 g/ml 4.4. Rigid upper mantleRigid upper mantle 5.5. asthenosphereasthenosphere 3.3 – 5.5 g/ml
  • 13. C.C. Lithosphere =Lithosphere = CrustCrust + Upper MantleUpper Mantle D.D. AsthenosphereAsthenosphere – the plastic-like layer– the plastic-like layer below the lithosphere in Earth’s Mantlebelow the lithosphere in Earth’s Mantle
  • 14. 3. Theory of Continental Drift3. Theory of Continental Drift a.a. Alfred WegnerAlfred Wegner –– proposed the theory ofproposed the theory of Continental Drift in theContinental Drift in the early 1900’s.early 1900’s. b.b. He proposed thatHe proposed that approximately 200 mya,approximately 200 mya, all the continents existedall the continents existed as one large land massas one large land mass which he calledwhich he called Pangaea.Pangaea.
  • 15. Dynamic CrustDynamic Crust  SCRAT’s take on Plate TectonicsSCRAT’s take on Plate Tectonics  For your viewing pleasure onlyFor your viewing pleasure only  Don’t believe everything you see in theDon’t believe everything you see in the movies....hahamovies....haha
  • 16. C. Evidence for Continental DriftC. Evidence for Continental Drift 1.1. Coastline of theCoastline of the continents – forcontinents – for example, the eastexample, the east coast ofcoast of SouthSouth AmericaAmerica fits wellfits well with the west coastwith the west coast ofof AfricaAfrica – like the– like the pieces of a giantpieces of a giant jig-jig- saw puzzle.saw puzzle.
  • 17. 2. Fossil Clues – certain fossils of2. Fossil Clues – certain fossils of ancient life formsancient life forms are found onare found on widely separated continents.widely separated continents.  MesosaurusMesosaurus was a smallwas a small freshwaterfreshwater reptile. It’sreptile. It’s fossils arefossils are found infound in AfricaAfrica andand SouthSouth AmericaAmerica
  • 18. GlossopterisGlossopteris – it was an ancient seed-fern– it was an ancient seed-fern (with very large heavy seeds). It’s fossils are(with very large heavy seeds). It’s fossils are found infound in Africa,Africa, India , Australia, Antarctica and South AmericaSouth America
  • 19. 3. Rock Clues3. Rock Clues a.a. TheThe AppalachianAppalachian Mountains of the easternMountains of the eastern US are geologicallyUS are geologically similar to the mountainssimilar to the mountains in Greenland andin Greenland and western Europe, whichwestern Europe, which include the Caledonianinclude the Caledonian Mountains of Scotland.Mountains of Scotland. b.b. Structure, age, andStructure, age, and mineral content of rocksmineral content of rocks are similar on the coastsare similar on the coasts of easternof eastern SouthSouth America and westernAmerica and western Africa.Africa.
  • 20. 4.4. Climate CluesClimate Clues a.a. Coal, which formsCoal, which forms from plants thatfrom plants that grow in warmgrow in warm swampyswampy environments, isenvironments, is found today in thefound today in the colder climates ofcolder climates of North America andNorth America and Antarctica.Antarctica.
  • 21. b. Coral limestone, containing the remains of coral,, containing the remains of coral, which once lived inwhich once lived in warm seaswarm seas, is found today in, is found today in northern latitudes such asnorthern latitudes such as North CarolinaNorth Carolina..
  • 22. c.c. Ancient rocks of theAncient rocks of the same agesame age near thenear the equator in Southequator in South America, SouthAmerica, South Africa and otherAfrica and other southernsouthern landmasses showlandmasses show evidence ofevidence of glaciationglaciation..
  • 23. Continental Drift LabContinental Drift Lab  Questions?Questions? 4. Where in the4. Where in the United States isUnited States is therethere measurablemeasurable evidence thatevidence that the continentsthe continents are movingare moving relative to onerelative to one another?another?
  • 24. C. Theory of Sea Floor SpreadingC. Theory of Sea Floor Spreading A.A. Topography of the ocean floorTopography of the ocean floor Label on your diagramLabel on your diagram SeamountSeamount Abyssal plainAbyssal plain Rift-valleyRift-valley Mid-Ocean RidgeMid-Ocean Ridge TrenchTrench Continental SlopeContinental Slope Continental ShelfContinental Shelf Mid-OceanRidge RiftValley
  • 25. B. Evidence for Sea Floor SpreadingB. Evidence for Sea Floor Spreading 1.1. Age Evidence – AsAge Evidence – As the distance fromthe distance from the ocean ridgethe ocean ridge increasesincreases, the age, the age of the rockof the rock increasesincreases.. youngest
  • 26. 2.2. Magnetic Evidence (PaleomagnetismMagnetic Evidence (Paleomagnetism) –) – magnetic clues from the iron-bearing basalt rockmagnetic clues from the iron-bearing basalt rock of the ocean floor supports the theory of seafloorof the ocean floor supports the theory of seafloor spreading.spreading.
  • 27. Add this to your notes Key Normal Reverse
  • 28. C. The Theory of Plate TectonicsC. The Theory of Plate Tectonics 1.1. The Theory of Plate Tectonics states that Earth’sThe Theory of Plate Tectonics states that Earth’s lithospherelithosphere (crust + upper mantle) is divided into(crust + upper mantle) is divided into sections calledsections called lithospheric plateslithospheric plates..
  • 29. 2.2. Plate MotionPlate Motion – The theory of Plate Tectonics states– The theory of Plate Tectonics states that these lithospheric plates are in motion and “float”that these lithospheric plates are in motion and “float” or ride on theor ride on the asthenosphereasthenosphere..
  • 30. 3.3. Direction of Plate Movement – the movement and interaction of tectonicDirection of Plate Movement – the movement and interaction of tectonic plates creates 3 types of plate boundaries: the arrows on the tectonicplates creates 3 types of plate boundaries: the arrows on the tectonic map in your notes show the relative motion.map in your notes show the relative motion.
  • 31. 4. Types of Plate Boundaries4. Types of Plate Boundaries
  • 32. A.A. Divergent Plate Boundaries –Divergent Plate Boundaries – where 2 plateswhere 2 plates are moving apartare moving apart 1. Ocean – Mid-Atlantic Ridge
  • 33. 2. Continental – Great Rift Valley, Africa
  • 34. B. Convergent Plate Boundaries –B. Convergent Plate Boundaries – Where 2 platesWhere 2 plates come together or collidecome together or collide.. 1. Oceanic-Continental – Subduction Zone Example: Nazca (oceanic) subducts under South American (continental)
  • 35. 2. Oceanic – Oceanic – Trenches and island arcs of Japan and Alleutian Islands (Alaska)
  • 36. 3. Continental – Continental – Indian/Australian Plate Colliding with Eurasian Plate forming the Himalaya Mountains
  • 37. C.C. Transform Plate BoundariesTransform Plate Boundaries –– 22 plates thatplates that “slip” past one another. Ex: San Andreas Fault“slip” past one another. Ex: San Andreas Fault
  • 38. D.D. Convection CurrentsConvection Currents == the driving force beneaththe driving force beneath plate tectonicsplate tectonics  Hot,Hot, LESSLESS densedense material from deepmaterial from deep within Earth’s mantlewithin Earth’s mantle rises. When this materialrises. When this material cools near the surface, itcools near the surface, it becomesbecomes MOREMORE densedense and sinks. The resultingand sinks. The resulting convective flow of thisconvective flow of this material in the mantlematerial in the mantle CARRIES/MOVESCARRIES/MOVES lithospheric plates acrosslithospheric plates across the surface of Earth.the surface of Earth. Label the diagram in your notes according to this diagram!
  • 39. EarthquakesEarthquakes
  • 40. III. EarthquakesIII. Earthquakes A.A. SeismologySeismology – the branch of science that– the branch of science that studies earthquakes.studies earthquakes.
  • 41. B. Causes of Earthquakes –B. Causes of Earthquakes – Sudden movement ofSudden movement of Earth’s crust at plate boundaries and faults.Earth’s crust at plate boundaries and faults. 1.1. Plate BoundariesPlate Boundaries Divergent Boundaries – usually minor, shallow quakes
  • 42. Convergent Boundary – Ocean – continent usually results in strong, deep earthquakes
  • 43. Convergent Boundary – Ocean – ocean, strong, deep quakes
  • 44. Transform Boundary – Strike-Slip Fault Moderate – shallow quakes
  • 45. San Francisco, CA 1906 Loma Prieta, CA 1989
  • 46. The 1906 San Francisco earthquake destroyed the City Hall in Santa Rosa (left). The equivalent of eight city blocks were destroyed by the earthquake.
  • 47. Northridge, CA 1994 Kobe, Japan 1995
  • 48. C. Earthquakes tell us about Earth’s surfaceC. Earthquakes tell us about Earth’s surface movementmovement KeyKey Shallow = within 75 km of Earth’s Surface Intermediate = 75 – 300 km Deep = 300 – 700 km
  • 49. D. Earthquakes cause other disastersD. Earthquakes cause other disasters TsunamiTsunami = gigantic sea waves= gigantic sea waves Characteristics:Characteristics: Speed =Speed = 400 – 500 mph400 – 500 mph Height =Height = 50 – 100 Feet50 – 100 Feet
  • 50. (3:10)(3:10)
  • 51. Features formed by tectonic activityFeatures formed by tectonic activity 1. Faults1. Faults Normal
  • 52. Reverse Fault
  • 53. Strike-slip or Transform Fault
  • 54. Grand Teton – Fault BlockGrand Teton – Fault Block
  • 55. 2. Earthquake Waves2. Earthquake Waves a. Origin and map locationa. Origin and map location Epicenter Focus Fault Depth FocusFocus = Point beneath Earth’s surface where fault movement releases seismic waves (energy) EpicenterEpicenter = the point on Earth’s surface directly above the focus.
  • 56. 1. Analysis of seismic waves has led scientists to infer the layerslayers of earth. b. Earthquake Waves and Earth’s Interiorb. Earthquake Waves and Earth’s Interior
  • 57. b. Types of seismic wavesb. Types of seismic waves  P WavesP Waves = P or Primary Waves- Also known as= P or Primary Waves- Also known as CompressionCompression waves - travel 6 mpswaves - travel 6 mps  Motion of matter due to P waves-alternate contractionMotion of matter due to P waves-alternate contraction and expansion of rocks in a direction parallel to theand expansion of rocks in a direction parallel to the direction of wave propagation.direction of wave propagation.
  • 58. b. Types of seismic wavesb. Types of seismic waves  S or Secondary Waves- Also known asS or Secondary Waves- Also known as Shear Waves andShear Waves and traveltravel atat 4 mps4 mps  Motion of matter due to S waves-displacement of adjacent rocks inMotion of matter due to S waves-displacement of adjacent rocks in a directiona direction perpendicularperpendicular to the direction of wave propagation.to the direction of wave propagation.  The velocity of P and S waves is controlled by how the materialThe velocity of P and S waves is controlled by how the material through which wave is traveling responds to shear forces. It alsothrough which wave is traveling responds to shear forces. It also depends on thedepends on the densitydensity of the material.of the material.
  • 59. b. Types of seismic wavesb. Types of seismic waves  Love wavesLove waves surfacesurface seismic wavesseismic waves are thatare that cause horizontal shifting ofcause horizontal shifting of the Earth during anthe Earth during an earthquakeearthquake
  • 60. C. Seismograph –C. Seismograph – measures andmeasures and records earthquake wavesrecords earthquake waves
  • 61. SeismologySeismology
  • 62. D. Locating the Epicenter 1. Need at least three (3) stations 2. Determine when P wave arrives 3. Determine when S wave arrives 4. Difference between S and P wave arrival ( t) EX: 4 min 20 seconds 5. Locate on travel-time curve what the ( t) corresponds to in distance 6. Draw circles around each station with radii=distance just determined 7. Intersection of three circles is the epicenter Using Seismic Waves to Study Earthquakes
  • 63. •Seismic Waves travel through the entire Earth •Travel at different rates through different densitiesdensities! •That’s why the lines “bendbend”…….when they go through the layers Earth’s structure/interior is divided into the crust, mantle, outer core and inner core. E. Earthquake Waves
  • 64. F. Measuring an Earthquake 1. Richter Scale – a scale used to express the strength or energy an earthquake
  • 65. 2. Mercalli Scale – a scale used to show the damage caused by an earthquake by assigning a number from I to XII
  • 66. Mark off 4:20
  • 67. Using the Drawing CompassUsing the Drawing Compass SUMMARYSUMMARY  Read the seismograph times of P/S waveRead the seismograph times of P/S wave  Or calculate the difference between the P-S waveOr calculate the difference between the P-S wave arrival stationsarrival stations  Use the graph on to determine the distance to theUse the graph on to determine the distance to the epicenter.epicenter.  Use the map scale to measure the distance from eachUse the map scale to measure the distance from each of the 3 locations and draw a circle around each city.of the 3 locations and draw a circle around each city.  The point of intersection of the 3 circles is theThe point of intersection of the 3 circles is the EPICENTER!EPICENTER!
  • 68. D. LocatingD. Locating the epicenter ofthe epicenter of an earthquakean earthquake Method of Triangulation VIRTUAL EARTHQUAKE Visit the WIKI and try it yourself!
  • 69. IV. VolcanoesIV. Volcanoes A. Volcanic Regions on Earth Ring of Fire = region of volcanoes that encircle the Pacific Ocean
  • 70. VolcanoesVolcanoes
  • 71. B. Causes of Volcanic ActivityB. Causes of Volcanic Activity 1.1. Plate BoundariesPlate Boundaries – island arc volcanoes– island arc volcanoes (Aleutians), subduction (Cascades, Andes)(Aleutians), subduction (Cascades, Andes)
  • 72. 2. Hot Spots –2. Hot Spots – Hawaiian IslandsHawaiian Islands a. Kaui 4 my b. Oahu 2.5 my c. Molokai 1.5 my d. Maui 1 my e. Hawaii O.8 my
  • 73. Mount St. Helens, WashingtonMount St. Helens, Washington
  • 74. Types of VolcanoesTypes of Volcanoes
  • 75. D. Volcanic FeaturesD. Volcanic Features 1. 9. 8. 7. 6. 5. 4. 3. 2. Neck
  • 76. Predicting VolcanoesPredicting Volcanoes D: #17