PLATE TECTONICS

1
PLATE TECTONICS

• Chapters 7, 8, 9
• Test 2 material
• End

2
LEGEND

• AZTEC INDIANS OF MEXICO SACRIFICED HUMANS TO KEEP
  AWAY EARTHQUAKES AND TO KEEP SUN ALIVE BY CUTTING
  OUT THE HEARTS OF THEIR VICTIMS AND THROWING THEM
  INTO VOLCANO

3
LEGEND

• IN WESTERN AFRICA THOUGHT THE JUNGLE WAS THE HAIR
  OF A GIANT. ALL LIVING THINGS THAT CREPT OR
  CRAWLED IN THE JUNGLE WERE LIKE LICE IN THE
  GIANTS HAIR. EARTHQUAKES WERE EXPLAINED AS THE
  GIANT SHAKING HIS HEAD TO GET RID OF THE LICE

4
LEGEND

• IN POLYNESIA TWO GODDESSES WERE FIGHTING THEIR
  WAY ACROSS THE PACIFIC. WHEREVER AN EARTHQUAKE
  OR VOLCANO OCCURRED, THIS WAS A BATTLE SITE. WHEN
  A GODDESS WAS SPURNED BY A LOVER SHE THREW A
  TANTRUM AND LAVA FLOWED

5
LEGEND

• VULCAN WAS THE ROMAN GOD WHO HAD A FORGE AT THE
  CENTER OF THE EARTH TO MAKE WEAPONS FOR THE GODS.
  WHENEVER HIS FORGE WAS WORKING LAVA SPEWED FORTH
  AT THE SURFACE.

6
LEGEND

• IN ICELAND VIKING LEGEND TALKS OF ODIN FRIGGA
  AND THEIR BELOVED SON BALDER. THE GOD OF
  MISCHIEF, LOKI, CONSPIRED TO HAVE BALDER KILLED.

7
FAMOUS VOLCANOES IN HISTORY

• MOUNT VESUVIUS
• MOUNT PELEE - WITH GLOWING CLOUD (NUEE ARDENTE)
• PARICUTIN
• KRAKATOA

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VESUVIUS
9
MT PELEE
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PARICUTIN
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Volcanoes Birth of Paricutin
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FAMOUS EARTHQUAKES

• GREAT ALASKA QUAKE OF 1964
• GREAT CHINA QUAKE
• NEW MADRID QUAKES OF 1811-1812
• MISSISSIPPI RIVER STOOD UP ON END
• CHURCH BELLS RANG IN BOSTON
• http//www.youtube.com/watch?v4Y-62Ti5_6s
• Pakistan quake of 2006

13
DR. IBEN BROWNING

• 1990 PREDICTED A 50 CHANCE OF EARTHQUAKE OF 6.5
  - 7.5 IN NEW MADRID BETWEEN DEC. 1-5, 1990
• CLAIMED A GREAT TIDAL STRAIN WOULD ALSO STRAIN
  THE SUBSURFACE
• RECEIVED NOTORIETY FOR PREDICTING SF QUAKE OF 1989

14
ARGUMENTS AGAINST DR. BROWNINGS THEORY

• NO FIRM SCIENTIFIC SUPPORT FOR HIS THEORY
• WAS A BIOLOGIST SPECIALIZING IN CLIMATOLOGY AND
  WAS NOT A GEOLOGIST OR SEISMOLOGIST
• ERRONOUS CLAIM TO FAME FOR PREDICTING SAN
  FRANCISCO EARTHQUAKE OF 1989

15

• TRANSCRIPTS REVEALED BROWNING PREDICTED AN
  EARTHQUAKE OF 6.0 WOULD OCCUR SOMETIME ON OR
  AROUND OCT 16TH (ACTUAL QUAKE WAS 17TH) SOMEWHERE
  IN WORLD.
• THESE QUAKES HAPPEN EVERY 3 DAYS SO NOT MUCH OF A
  FORECAST

16

• THE ONLY GEOLOGIST IN THE NATION SUPPORTING HIM
  HAD SHAKEY REPUTATION. HAD FLOWN OVER THE STATE
  OF NORTH CAROLINA USING A PSYCHIC TRYING TO
  LOCATE AREAS WHERE AN EARTHQUAKE WOULD STRIKE

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ALFRED WEGENER

• THEORY OF CONTINENTAL DRIFT PLATE TECTONICS
• PANGAEA
• LAURASIA
• GONDWANA
• GLOSSOPTERIS

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WHAT WAS EFFECT OF CONTINENTAL MOVEMENT?

• NEW CLIMATES ALONG COASTS
• NEW MOUNTAIN RANGES
• NEW DESERTS
• DRIFTING OF THE POLES
• PLANT AND ANIMAL LIFE SIMILARITIES IN AREAS ONCE
  UNITED

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SEA FLOOR SPREADING

• WEGENERS HYPOTHESIS WAS NOT READILY ACCEPTED
  BECAUSE IT FAILED TO PROVIDE MECHANISM FOR
  MOVEMENT
• ARTHUR HOLMES, GEOLOGIST THOUGHT THE SEA FLOORS
  WERE DRAGGING ALONG THE CONTINENTS WHICH RESTED
  ON TOP OF THEM

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Seafloor spreading
25

• THOUGHT CONVECTION PROCESS BEGAN BELOW EARTHS
  SURFACE WHICH PUSHED MATERIAL UPWARD TO FORM
  RIDGE SYSTEMS ON OCEAN FLOOR. MATERIAL WIDENS
  THE OCEANS BY 1 OR 2 INCHES PER YEAR

26
WHAT DID HOLMES FIND ON OCEANIC RIDGES?

• EQUAL DISTANCE
• EQUAL AGE
• EQUAL THICKNESS
• EQUAL MAGNETIC DIRECTION
• WHAT DOES THIS SUGGEST?

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PLATE BOUNDARIES

• DIVERGENT
• CONVERGENT
• TRANSFORM

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DIVERGENT PLATE BOUNDARIES

• FOUND NEAR SPREADING CENTERS AT THE MID-OCEANIC
  RIDGE SYSTEMS
• RIFT VALLEYS
• GREAT RIFT VALLEY OF AFRICA

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divergent
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Rift valley
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East africa rift
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CONVERGENT PLATE BOUNDARIES

• OCEAN CONTINENT
• OCEAN OCEAN
• CONTINENT CONTINENT

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convergent
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Continent to continent
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Ocean to ocean
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TRANSFORM PLATE BOUNDARIES

• SAN ANDREAS FAULT
• MOVING TO NORTH/NORTHWEST AT A RATE OF 35
  MILLIMETERS PER YEAR

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transform
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EARTHQUAKE

• VIBRATION OF THE EARTH PRODUCED BY THE RAPID
  RELEASE OF ENERGY ALONG FAULTS
• THIS ENERGY RADIATES OUTWARD FROM THE SOURCE OF
  THE QUAKE KNOWN AS THE FOCUS

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focus
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Elastic rebound
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EPICENTER

• THE AREA ON THE EARTHS SURFACE IMMEDIATELY ABOVE
  THE FOCUS
• IT IS NOT THE SOURCE OF THE QUAKE

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FAULTS

• PRODUCED BY THE NEVER ENDING MOVEMENT OF THE
  EARTHS CRUST
• FIND FAULTS AND EARTHQUAKES NEAR PLATE BOUNDARIES

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OTHER QUAKES

• FORESHOCKS - QUAKES THAT PRECEDE THE MAIN
  EARTHQUAKE
• AFTERSHOCKS - QUAKES THAT FOLLOW THE MAIN
  EARTHQUAKE

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EARTHQUAKE RECORDINGS

• SEISMOLOGY
• SEISMOGRAPH
• SEISMOGRAM
• RICHTER SCALE - LOGARITHMIC SCALE USED TO MEASURE
  THE ENERGY AND THE WAVE AMPLITUDE OF THE
  EARTHQUAKE

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seismograph
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seismogram
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.

• ONE MILLION EARTHQUAKES OCCUR EVERY YEAR
• 6.0 OCCURS EVERY THREE DAYS
• ABOVE 8.0 ONCE EVERY 5/10 YEARS
• BELOW 2.5 ARE NOT FELT BUT CAN BE MEASURED

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RICHTER SCALE INCREMENTS

• AN INCREASE OF 1.0 A 10 TIMES INCREASE IN WAVE
  AMPLITUDE AND A 31.5 TIMES INCREASE IN ENERGY
• AN INCREASE OF 2.0 A 100 TIMES INCREASE IN
  AMPLITUDE AND A 992.25 INCREASE IN ENERGY (31.5 X
  31.5)

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EARTHQUAKE WAVES

• SURFACE WAVES - TRAVEL ALONG EARTHS OUTER LAYER
• BODY WAVES - TRAVEL THROUGH EARTHS INTERIOR
• PRIMARY WAVES P WAVES - COMPRESS EXPAND ROCKS
  IN THE DIRECTION WAVE TRAVELS
• SECONDARY WAVES S WAVES - SHAKE THE PARTICLES
  AT RIGHT ANGLES TO DIRECTION OF TRAVEL

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pwave
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swave
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FINDING EARTHQUAKE EPICENTERS

• P WAVES ARRIVE AHEAD OF S WAVES. THE GREATER THE
  DISTANCE AWAY FROM EPICENTER THE LONGER THE TIME
  SPAN FROM P WAVE TO S WAVE. USE TRAVEL TIME
  GRAPHS FROM 3 OR MORE DIFFERENT STATIONS
  TRIANGULATION THE INTERSECTING POINT IS THE
  EPICENTER

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Finding epi
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Epi circles
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MERCALLI INTENSITY SCALE

• ASSESSES DAMAGE FROM A QUAKE AT A SPECIFIC
  LOCATION
• I - NOT FELT
• II - FELT ONLY ON UPPER FLOORS
• VI - HEAVY FURNITURE MOVED
• X - MOST FRAME STRUCTURES DESTROYED
• XII - DAMAGE TOTAL

57
PRECURSORS

• PHENOMENA THAT PRECEDE THUS PROVIDE A WARNING
  OF A FORTHCOMING EARTHQUAKE
• UPLIFT, SUBSIDENCE, AND STRAIN IN THE ROCKS NEAR
  ACTIVE FAULTS
• PECULIAR BEHAVIOR

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EARTHS INTERIOR STRUCTURE

• CORE - SOLID INNER MADE UP OF IRON AND LIQUID
  OUTER CORE
• MANTLE - LOWER IS A MIXTURE OF IRON, MAGNESIUM,
  AND SILICATES. UPPER MANTLE IS RIGID. UPPERMOST
  MANTLE IS WHERE THE LITHOSPHERE BEGINS
• CRUST - SOLID EARTH SURFACE

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Earth structure
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MOHOROVICIC DISCONTINUITY MOHO

• THE BOUNDARY SEPARATING THE CRUST FROM THE MANTLE
  , DISCERNIBLE BY AN INCREASE IN SEISMIC VELOCITY

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LITHOSPHERE

• THE OUTERMOST RIGID UNIT CRUST UPPERMOST
  MANTLE OF THE EARTH AVERAGING ABOUT 100
  KILOMETERS 62 MILES IN THICKNESS. THICKER OVER
  THE CONTINENTS THINNER OVER THE OCEAN BASINS

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ASTHENOSPHERE

• BENEATH THE LITHOSPHERE TO A DEPTH OF ABOUT 660
  KILOMETERS 410 MILES. TOP PART HAS MELTED
  ALLOWING LITHOSPHERE TO EFFECTIVELY DETACH FROM
  THE ASTHENOSPHERE BELOW
• IMPORTANT FOR PLATE TECTONICS THEORY

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asthenosphere
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CRUSTAL DEFORMATION

• FOLDING - THE COMPRESSION OF ROCK
• SYNCLINES ARE DOWNFOLDS OF ROCK
• ANTICLINES ARE UPFOLDS OF ROCK

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folding
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FAULTING

• FRACTURES IN ROCK INVOLVING DISPLACEMENT OF ROCK
  ON ONE SIDE WITH RESPECT TO THE OTHER
• A JOINT IS A FRACTURE WITHOUT DISPLACEMENT

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NORMAL FAULT

• STRESSES PULL CRUSTAL ROCK APART CREATING MORE
  HORIZONTAL SPACE

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Normal fault
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REVERSE FAULT

• ONE BLOCK RIDING OVER THE OTHER COMPRESSING IT
  INTO SMALLER HORIZONTAL SPACE

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Reverse fault
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STRIKE SLIP FAULT

• HORIZONTAL MOVEMENT SUCH AS IN A TRANSFORM FAULT

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Strike slip
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CRUSTAL DEFORMATION FEATURES

• GRABEN - SUNKEN BLOCKS BETWEEN USUALLY PARALLEL
  NORMAL FAULTS AS IN A RIFT VALLEY
• HORST - A BLOCK RAISED BETWEEN REVERSE FAULTS

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Graben and horst
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HORST
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GRABEN
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VOLCANOES

• LAVA
• MAGMA
• PYROCLASTICS
• LAPILLI - WALNUT-SIZED
• CINDERS - PEA-SIZED
• BLOCK

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LAPILLI
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FACTORS DETERMINING TYPE OF ERUPTION

• MAGMAS COMPOSITION
• TEMPERATURE
• AMOUNT OF DISSOLVED GASES
• THESE FACTORS AFFECT THE MAGMAS VISCOSITY OR
  THICKNESS. MORE VISCOUS LAVA EQUALS MORE VIOLENT
  ERUPTION

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WHERE DO WE FIND VOLCANOES?

• SUBDUCTION BOUNDARIES
• SEA FLOOR SPREADING CENTERS
• HOT SPOTS
• LOIHI

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loihi
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TYPES OF VOLCANIC ERUPTIONS

• EFFUSIVE ERRUPTIONS ARE GENTLE USUALLY CONSISTING
  OF LAVA. THEY PRODUCE SHIELD VOLCANOES WHICH ARE
  VERY BROAD GENTLY SLOPING CRATERS SUCH AS WE HAVE
  IN HAWAII

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Shield volcano
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.

• EXPLOSIVE ERUPTIONS CAN PRODUCE TWO TYPES OF
  VOLCANIC CONES. IF THE MATERIAL IS SOLELY
  PYROCLASTICS, A CINDER CONE IS PRODUCED. THIS IS
  A SMALL STEEPLY SLOPED CRATER

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Cinder cone
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• IF THE ERUPTION ALTERNATES BETWEEN PRODUCING LAVA
  AND PYROCLASTICS, A COMPOSITE CONE OR STRATO
  VOLCANO IS PRODUCED. IN THESE THERE ARE
  ALTERNATING LAYERS OF LAVA AND PYROCLASTIC

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Composite cone
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LAVA TYPES

• PAHOEHOE - HOTTEST (2000 DEGREES F) AND HAS
  SMOOTH AND ROPEY TEXTURE
• AA - COOLER (1800 DEGREES F) AND IS JAGGED AND
  BLOCKY
• CLINKERS - 1600 DEGREES F, GETS ITS NAME FROM ITS
  SOUND

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pahoehoe
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aa
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VOLCANIC FEATURES

• CALDERA (KETTLE) - BASIN SHAPED DEPRESSION -
  VALLE GRANDE IN NEW MEXICO OR CRATER LAKE, OREGON
• PACIFIC RING OF FIRE
• NUEE ARDENTE MT PELEE

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Valle grande
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.
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• PLUG DOMES
• VOLCANIC NECKS - SHIPROCK, NM
• DIKE RIDGE
• SILL
• LACCOLITH - A MASSIVE IGNEOUS BODY INTRUDED
  BETWEEN PRE-EXISTING STRATA
• BATHOLITH EROSION EXPOSED MASS
• LAHAR - MUDFLOWS

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IGNEOUS LANDFORMS
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Plug dome
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Ship rock
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SILL
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batholith
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TEST 2 REVIEW

• How will you do?

101
Fossils can be all but which of the following?

• A. Indirect Evidence
• B. Actual Remains
• C. Sedimentation
• D. Imprint
• Correct Response
• C. Sedimentation

102
2. Which statement is true about the Earths
crust?

• A. Continental rocks are heavier than ocean rocks
• B. Granite is a type of ocean rock
• C. Basalt is heavier than Granite
• D. Continental rocks are called sima
• Correct response
• C. basalt is heavier than granite

103
3. Smaller-sized crystals are found in what type
of rock?

• A. Intrusive
• B. Extrusive
• C. Silicates
• D. None of these
• Correct response
• B. extrusive

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4. Before it was a gneiss rock what was it?

• A. marble
• B. sandstone
• C. mica
• D. granite
• Correct response?
• D. granite

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5. The San Andreas fault is what type of boundary?

• A. divergent
• B. convergent
• C. transform
• D. Spreading center
• Correct response?
• C. transform

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6. Pahoehoe is?

• A. a jagged and blocky type of lava
• B. cooler than aa
• C. smooth and ropey textured lava
• D. the name of the new Hawaiian Island
• Correct response
• C. smooth and ropey textured lava

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7. Valle Grande Crater Lake are examples of

• A. calderas
• B. plug domes
• C. dike ridges
• D. laccoliths
• Correct response?
• A. calderas

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8. Iben Browning was famous for?

• A. his work in plate tectonics
• B. his work as a seismologist
• C. his faulty New Madrid prediction
• D. A B are true
• Correct response?
• C. his faulty NM prediction

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POSITIVE ASPECTS OF VOLCANIC ACTIVITY

• PRODUCES EXCELLENT AGRICULTURAL SOILS
• HELPS TO FORM METALLIC ORES
• PRODUCES GEOTHERMAL ENERGY
• ADDS GASES TO OUR ATMOSPHERE
• ADDS CONDENSATION SURFACES