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Dynamic Crust

Dynamic Crust. THEORY OF CONTINENTAL DRIFT. (ALFRED WEGENER 1915 ). I PANGEA- A LARGE LANDMASS CONTAINING ALL OF THE CONTINENTS. WHICH EVENTUALLY BROKE INTO TWO LANDMASSES. a) LAURASIA- N. AMERICA,EUROPE, ASIA. b) GONDWANALAND- AFRICA, S. AMERICA, ANTARCTICA, AUSTRALIA, INDIA. Evidence.

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Dynamic Crust

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  1. Dynamic Crust

  2. THEORY OF CONTINENTAL DRIFT (ALFRED WEGENER 1915) I PANGEA- A LARGE LANDMASS CONTAINING ALL OF THE CONTINENTS. WHICH EVENTUALLY BROKE INTO TWO LANDMASSES a) LAURASIA- N. AMERICA,EUROPE, ASIA b) GONDWANALAND- AFRICA, S. AMERICA, ANTARCTICA, AUSTRALIA, INDIA

  3. Evidence CONTINENTS SEEM TO FIT TOGETHER FOSSILS OF INDIVIDUAL SPECIES CAN BE FOUND ON MANY DIFFERENT CONTINENTS WHICH ARE NOT CLOSE TOGETHER. (EX. LYSTROSAURUS WAS LOCATED IN ANTARCTICA, S. AMERICA, AFRICA, INDIA) DEPOSITS OF CERTAIN ROCK AND MINERAL TYPES CORRELATE AMONG CONTINENTS APPALACHIAN MTS. FOUND IN NORTHEAST OF U.S. ARE SIMILAR IN AGE AND STRUCTURE AS MTS. IN GREENLAND AND SCANDINAVIA

  4. Structure of the Earth PRESSURE AND TEMPERATURE INCREASE AS YOU MOVE TOWARD THE CENTER OF THE EARTH CRUST- THE OUTER MOST LAYER OF THE EARTH a) CONTINENTAL CRUST- COMPOSED MAINLY OF GRANITE, LOW IN DENSITY b) OCEANIC CRUST- COMPOSED MAINLY OF BASALT, HIGH IN DENSITY

  5. LITHOSPHERE- CRUST AND UPPERMOST SOLID PART OF THE MANTLE  ASTHENOSPHERE- UNDERLIES THE LITHOSPHERE, COMPOSED OF PARTIALLY MOLTEN ROCK MOHO- THE BOUNDARY BETWEEN THE CRUST AND THE MANTLE MANTLE- THE LAYER OF MOLTEN ROCK EXTENDING FROM THE CRUST DOWNWARD 2850 KM OUTER CORE- BETWEEN MANTLE AND INNER CORE, COMPOSED OF IRON AND NICKEL INNER CORE- SOLID IRON AND NICKEL LOCATED AT THE CENTER OF THE EARTH

  6. Please turn to the Inferred Properties of Earth’s Interior chart on page 10 in the ESRT

  7. Plate Tectonics PLATE TECTONICS IS THE STUDY OF THE FORMATION AND MOVEMENT OF PLATES PLATES ARE COMPOSED OF LITHOSPHERE (CONTINENTAL=THICK, OCEANIC=THIN) 12 MAJOR AND SEVERAL MINOR PLATES

  8. Convection Cells

  9. ** PLATES MOVE BECAUSE OF CONVECTION CELLS IN THE ASTHENOSPHERE** CONVECTIONCELL- A CIRCULATORY MOTION IN A LIQUID OR GAS TRANSFERRING HEAT ENERGY THAT RESULTS FROM DIFFERENCES IN DENSITY WITHIN THE FLUID

  10. Types of Plate Boundaries Divergent Convergent Transform

  11. Divergent Plate Boundary *PLACE WHERE TWO PLATES ARE MOVING APART FROM EACH OTHER. Sea Floor Spreading a) MID-ATLANTIC RIDGE- SEA FLOOR SPREADING AT THE MID OCEAN RIDGES RECORDED BY THE REVERSAL OF THE MAGNETIC POLES IN MINERAL GRAINS

  12. PALEOMAGNETISM- THE STUDY OF MAGNETISM IN ANCIENT ROCKS POLAR WANDERING- AS METALLIC MINERAL GRAINS ALIGN THEMSELVES WITH THEIR MAGNETIC POLES ROCK RECORDS SHOW THAT THE GRAINS REVERSE THE DIRECTION IN WHICH THEY POINT Reversal of Magnetic Poles

  13. Convergent Plate Boundary COLLISION- WHEN TWO PLATES CARRYING CONTINENTS COLLIDE THEY PUSH UP USUALLY CAUSING MOUNTAINS. (EX. HIMALAYAS) SUBDUCTION- WHEN BOTH PLATES DO NOT CONTAIN CONTINENTS, ONE OF THE PLATES IS FORCED TO SINK UNDER THE OTHER ONE.

  14. THE PLATE WHICH SUBDUES IS COMPOSED OF A MORE DENSE MATERIAL OCEAN-CONTINENT THE OCEAN FLOOR IS MORE DENSE SO IT SUBDUES TO THE CONTINENTAL CAUSING OFFSHORE TRENCHES, MOUNTAINS OR VOLCANOES (EX. WESTERN COAST OF S. AMERICA OCEAN-OCEAN ONE PLATE WILL SUBDUE TO THE OTHER ONE USUALLY CAUSING A DEEP TRENCH (EX. MARIANA’S TRENCH)

  15. Transform Plate Boundary WHEN PLATES SLIDE PAST ONE ANOTHER USUALLY CAUSING A BUILD UP OF PRESSURE WHICH IS RELEASED IN THE FORM OF AN EARTHQUAKE SAN ANDREAS FAULT- MANY EARTHQUAKES ARE COMMON ALONG THE FAULT WHERE THE NORTH AMERICAN PLATE IS SLIDING PAST THE PACIFIC PLATE

  16. Now you are going to draw your own plate boundaries!

  17. Evidence Earthquakes and Volcanic activity

  18. More Evidence..

  19. The Ring of Fire

  20. Volcanism MAGMA – MOLTEN ROCK UNDERGROUND FELSIC – MAGMAS WITH RELATIVELY HIGH SILICA ARE THICK, LIGHT COLORED, AND SLOW MOVING MAFIC – RELATIVELY LOW SILICA CONTENT, THINNER, DARKER, AND FLOW MORE EASILY

  21. MAGMA CONTAINS DISSOLVED GASES THAT ARE GIVEN OFF AS THE MAGMA ERUPTS. THE MOST IMPORTANT OF THESE GASES ARE WATER VAPOR, CARBON DIOXIDE, AND SULFUR. MAGMAS CONTAINING LARGE AMOUNTS OF DISSOLVED GASES TEND TO PRODUCE MORE EXPLOSIVE ERUPTIONS. LAVA – MOLTEN ROCK THAT HAS REACHED THE SURFACE FELSIC LAVA – THICK AND STIFF CALLED AA LAVA. PRODUCE EXPLOSIVE ERUPTIONS. MAFIC LAVA – THIN AND FLUID CALLED PAHOEHOE LAVA. LAVA POURS OUT SMOOTHLY (LESS EXPLOSIVE)

  22. LAVA FRAGMENTS TEPHRA – SOLID FRAGMENTS OF LAVA PRODUCED FROM EXPLOSIVE ERUPTIONS. SMALL ASH LAPILLI BOMBS LARGE

  23. KINDS OF ERUPTIONS RIFT ERUPTIONS – OCCUR AT LONG, NARROW FRACTURES IN THE CRUST SUCH AS MID-OCEAN SPREADING CENTERS WHEN LAVA FLOWS OUT SMOOTHLY AND FLUIDLY IT FORMS A VOLCANIC MOUNTAIN WITH A BROAD BASE AND GENTLY SLOPING SIDES CALLED A SHIELD CONE

  24. SUBDUCTION BOUNDARY ERUPTIONS – ARE THE RESULT OF THICK MAGMA THAT FORMS AT SUBDUCTION BOUNDARIES. THESE ERUPTIONS AR MORE EXPLOSIVE DUE TO THE LARGE AMOUNT OF GASES IN THE MAGMA. FORMS A CINDER CONE WITH VERY STEEP SIDES

  25. HOT SPOTS HOT SPOTS ARE AREAS OF VOLCANIC ACTIVITY IN THE MIDDLE OF LITHOSPHERIC PLATES. SIMILAR TO RIFT ERUPTIONS. SMOOTH FLOWING LAVA AND SHIELD CONES. ** THE HOT SPOT STAYS IN THE SAME LOCATION AS THE LITHOSPHERIC PLATE ABOVE IT MOVES **

  26. EARTHQUAKES AN EARTHQUAKE IS A SHAKING OF EARTH’S CRUST CAUSED BY THE RELEASE OF ENERGY. REASONS WHY THEY OCCUR: ERUPTION OF A VOLCANO THE COLLAPSE OF A CAVERN THE IMPACT OF A METEOR SUDDEN MOVEMENT ALONG A PLATE BOUNDARY CAUSED BY THE RELEASE OF STRESS

  27. DEPTH OF EARTHQUAKES FOCUS – THE POINT ON A FAULT PLANE AT WHICH THE FIRST MOVEMENT OCCURS EPICENTER – THE POINT ON EARTH’S SURFACE DIRECTLY ABOVE THE FOCUS

  28. EARTHQUAKE WAVES THREE BASIC KINDS OF WAVES P-WAVES (PRIMARY) – BACK AND FORTH WAVE MOTION; CAN TRAVEL THROUGH ANY MATERIAL; FASTEST S-WAVES (SECONDARY) – SIDE TO SIDE WAVE MOTION; CAN TRAVEL THROUGH SOLIDS BUT NOT THROUGH LIQUIDS OR GASES L-WAVES (SURFACE) – FORM WHEN P AND S WAVES REACH THE SURFACE WHICH MOVE SLOWLY LIKE RIPPLES ON A POND; SLOWEST

  29. LOCATING AN EARTHQUAKE SEISMOGRAPH – THE INSTRUMENT THAT DETECTS AND RECORDS EARTHQUAKE WAVES SEISMOGRAM – THE SHEET WHICH DISPLAYS THE ZIG-ZAG TRACE OF EARTHQUAKE WAVES **P-WAVES ALWAYS ARRIVE BEFORE S-WAVES** P AND S WAVE ARRIVAL TIME DIFFERENCE CAN THEN BE USED TO DETERMINE THE DISTANCE FROM THE RECORDING STATION TO THE EPICENTER

  30. SHADOW ZONE THE SHADOW ZONE IS A WIDE BELT AROUND EARTH ON THE SIDE OPPOSITE THE FOCUS OF THE EARTHQUAKE. SEISMIC STATIONS RECEIVE NEITHER P NOR S WAVES. THE CAUSE OF THE SHADOW ZONE IS THE EARTH’S OUTER CORE. S-WAVES CAN NOT TRAVEL THROUGH THE LIQUID OUTER CORE. WHILE P WAVES ARE REFRACTED (BENT) IN A SMOOTH ARC BACK TO THE SURFACE.

  31. OTHER CRUSTAL CHANGES ORIGINAL HORIZONTALITY- CONCEPT THAT SEDIMENTARY ROCKS FORM IN HORIZONTAL LAYERS PARALLEL TO THE EARTH’S SURFACE. DEFORMED ROCKS- ANY ROCK LAYERS WHICH NO LONGER SHOW HORIZONTALITY UPLIFT- LAND WHICH HAS BEEN RAISED UP TO ITS PRESENT POSITION (EVIDENCE- MARINE FOSSILS IN MOUNTAINS) FOLDS- ROCK LAYERS WHICH ARE BENT OR CURVED CAUSED FROM GREAT PRESSURE ON THE ROCK

  32. OTHER CRUSTAL CHANGES FOLDS- ROCK LAYERS WHICH ARE BENT OR CURVED CAUSED FROM GREAT PRESSURE ON THE ROCK FAULTS- ROCK LAYERS OFFSET OR DISPLACED ALONG A CRACK HANGING WALL- IS ON THE TOP OF THE CRACK FOOT WALL- IS ON THE BOTTOM OF THE CRACK

  33. PLEASE TURN TO PAGE 11 IN YOUR ESRT

  34. Review of Plate Boundaries Who created the theory of “continental drift” ? Give two forms of evidence to support this theory. What is the difference between the lithosphere and the asthenosphere? Describe how a convection cell works.

  35. Review of Plate Boundaries What type of boundary is this?

  36. Review of Plate Boundaries What type of boundary is this?

  37. Review of Plate Boundaries What type of boundary is this?

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