Transcript PLATE TECTONICS

PLATE TECTONICS
Chapters 7, 8, & 9
Test 2 material
End
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
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 GIANT’S HAIR.
EARTHQUAKES WERE EXPLAINED
AS THE GIANT SHAKING HIS HEAD
TO GET RID OF THE LICE
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
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.
LEGEND
 IN ICELAND VIKING LEGEND TALKS
OF ODIN & FRIGGA AND THEIR
BELOVED SON BALDER. THE GOD
OF MISCHIEF, LOKI, CONSPIRED TO
HAVE BALDER KILLED.
FAMOUS VOLCANOES IN
HISTORY
 MOUNT VESUVIUS
 MOUNT PELEE - WITH GLOWING
CLOUD (NUEE ARDENTE)
 PARICUTIN
 KRAKATOA
VESUVIUS
MT PELEE
PARICUTIN
Volcanoes – Birth of Paricutin
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?v=4Y-
62Ti5_6s
 Pakistan quake of 2006
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
ARGUMENTS AGAINST DR.
BROWNING’S 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
 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
 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
ALFRED WEGENER
 THEORY OF




CONTINENTAL
DRIFT & PLATE
TECTONICS
PANGAEA
LAURASIA
GONDWANA
GLOSSOPTERIS
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
SEA FLOOR SPREADING
 WEGENER’S 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
Seafloor spreading
 THOUGHT CONVECTION PROCESS
BEGAN BELOW EARTH’S SURFACE
WHICH PUSHED MATERIAL
UPWARD TO FORM RIDGE
SYSTEMS ON OCEAN FLOOR.
MATERIAL WIDENS THE OCEANS BY
1 OR 2 INCHES PER YEAR
WHAT DID HOLMES FIND
ON OCEANIC RIDGES?
 EQUAL DISTANCE
 EQUAL AGE
 EQUAL THICKNESS
 EQUAL MAGNETIC DIRECTION
 WHAT DOES THIS SUGGEST?
PLATE BOUNDARIES
 DIVERGENT
 CONVERGENT
 TRANSFORM
DIVERGENT PLATE
BOUNDARIES
 FOUND NEAR SPREADING
CENTERS & AT THE MID-OCEANIC
RIDGE SYSTEMS
 RIFT VALLEYS
 GREAT RIFT VALLEY OF AFRICA
divergent
Rift valley
East africa rift
CONVERGENT PLATE
BOUNDARIES
 OCEAN & CONTINENT
 OCEAN & OCEAN
 CONTINENT & CONTINENT
convergent
Continent to continent
Ocean to ocean
TRANSFORM PLATE
BOUNDARIES
 SAN ANDREAS FAULT
 MOVING TO NORTH/NORTHWEST AT
A RATE OF 35 MILLIMETERS PER
YEAR
transform
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
focus
Elastic rebound
EPICENTER
 THE AREA ON THE EARTH’S
SURFACE IMMEDIATELY ABOVE
THE FOCUS
 IT IS NOT THE SOURCE OF THE
QUAKE
FAULTS
 PRODUCED BY THE NEVER ENDING
MOVEMENT OF THE EARTH’S
CRUST
 FIND FAULTS AND EARTHQUAKES
NEAR PLATE BOUNDARIES
OTHER QUAKES
 FORESHOCKS - QUAKES THAT
PRECEDE THE MAIN EARTHQUAKE
 AFTERSHOCKS - QUAKES THAT
FOLLOW THE MAIN EARTHQUAKE
EARTHQUAKE
RECORDINGS
 SEISMOLOGY
 SEISMOGRAPH
 SEISMOGRAM
 RICHTER SCALE - LOGARITHMIC
SCALE USED TO MEASURE THE
ENERGY AND THE WAVE
AMPLITUDE OF THE EARTHQUAKE
seismograph
seismogram
.
 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
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)
EARTHQUAKE WAVES
 SURFACE WAVES - TRAVEL ALONG
EARTH’S OUTER LAYER
 BODY WAVES - TRAVEL THROUGH
EARTH’S 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
pwave
swave
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
Finding epi
Epi circles
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
PRECURSORS
 PHENOMENA THAT PRECEDE &
THUS PROVIDE A WARNING OF A
FORTHCOMING EARTHQUAKE
 UPLIFT,
SUBSIDENCE, AND STRAIN IN
THE ROCKS NEAR ACTIVE FAULTS
 PECULIAR BEHAVIOR
EARTH’S 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
Earth structure
MOHOROVICIC
DISCONTINUITY [MOHO]
 THE BOUNDARY SEPARATING THE
CRUST FROM THE MANTLE ,
DISCERNIBLE BY AN INCREASE IN
SEISMIC VELOCITY
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
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
asthenosphere
CRUSTAL DEFORMATION
 FOLDING - THE COMPRESSION OF
ROCK
 SYNCLINES ARE DOWNFOLDS OF
ROCK
 ANTICLINES ARE UPFOLDS OF
ROCK
folding
FAULTING
 FRACTURES IN ROCK INVOLVING
DISPLACEMENT OF ROCK ON ONE
SIDE WITH RESPECT TO THE
OTHER
 A JOINT IS A FRACTURE WITHOUT
DISPLACEMENT
NORMAL FAULT
 STRESSES PULL CRUSTAL ROCK
APART CREATING MORE
HORIZONTAL SPACE
Normal fault
REVERSE FAULT
 ONE BLOCK RIDING OVER THE
OTHER COMPRESSING IT INTO
SMALLER HORIZONTAL SPACE
Reverse fault
STRIKE SLIP FAULT
 HORIZONTAL MOVEMENT SUCH AS
IN A TRANSFORM FAULT
Strike slip
CRUSTAL DEFORMATION
FEATURES
 GRABEN - SUNKEN BLOCKS
BETWEEN USUALLY PARALLEL
NORMAL FAULTS AS IN A RIFT
VALLEY
 HORST - A BLOCK RAISED
BETWEEN REVERSE FAULTS
Graben and horst
HORST
GRABEN
VOLCANOES
 LAVA
 MAGMA
 PYROCLASTICS
 LAPILLI - WALNUTSIZED
 CINDERS - PEASIZED
 BLOCK
LAPILLI
FACTORS DETERMINING
TYPE OF ERUPTION
 MAGMA’S COMPOSITION
 TEMPERATURE
 AMOUNT OF DISSOLVED GASES
 THESE FACTORS AFFECT THE
MAGMA’S VISCOSITY OR
THICKNESS. MORE VISCOUS LAVA
EQUALS MORE VIOLENT ERUPTION
WHERE DO WE FIND
VOLCANOES?
 SUBDUCTION BOUNDARIES
 SEA FLOOR SPREADING CENTERS
 HOT SPOTS
 LOIHI
loihi
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
Shield volcano
.
 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
Cinder cone
 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
Composite cone
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
pahoehoe
aa
VOLCANIC FEATURES
 CALDERA (KETTLE) - BASIN SHAPED
DEPRESSION - VALLE GRANDE IN
NEW MEXICO OR CRATER LAKE,
OREGON
 PACIFIC RING OF FIRE
 NUEE ARDENTE – MT PELEE
Valle grande
.
 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
IGNEOUS LANDFORMS
Plug dome
Ship rock
SILL
batholith
TEST 2 REVIEW
 How will you do?
Fossils can be all but which of
the following?
 A. Indirect Evidence
 B. Actual Remains
 C. Sedimentation
 D. Imprint
 Correct Response
 C. Sedimentation
2. Which statement is true about
the Earth’s 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
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
4. Before it was a gneiss rock
what was it?
 A. marble
 B. sandstone
 C. mica
 D. granite
 Correct response?
 D. granite
5. The San Andreas fault is what
type of boundary?
 A. divergent
 B. convergent
 C. transform
 D. Spreading center
 Correct response?
 C. transform
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
7. Valle Grande & Crater Lake
are examples of:
 A. calderas
 B. plug domes
 C. dike ridges
 D. laccoliths
 Correct response?
 A. calderas
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
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