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Plate tectonics.notebook
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Structure of the Earth
Chapter 7
The Earth is divided into 3 Main Layers1. Crust
outermost layer 1% of the Earth’s mass thickness varies: 5100 kmtwo types:
oceanic densercontinental
Mohorovicic discontinuity separates the crust and the upper mantle.
2. Mantlelargest layer 67% of Earth’s massmade of silicon, oxygen, magnesium, ironsolid and liquid: plasticlike
Lithospheremade up of the crust and upper mantledivided into tectonic plates
Asthenosphereplasticlike layer below the lithosphere plates float soft solid rock that moves very slowly
Mesospherethe lower part of the mantle to the outer core
Gutenberg Discontinuityseparates the mantle and the core
3. Coreinnermost part of the Earth33% of the Earth’s mass
Outer coreliquidmade of iron and nickel
Lehmann Discontinuityseparates the outer and inner core
Inner Coresolid: due to the pressurevery dense iron and nickel
scientists believe that the inner core rotates faster than therest of the planet
speed = lap the Earth's surface once every 400 years
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A. Mohorovicic Discontinuity 1. Continental Crust 2. Oceanic Crust B. Gutenberg Discontinuity 3. Asthenosphere 4. Mesosphere C. Lehmann Discontinuity 5. Outer Core 6. Inner Core
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Section 2 Restless Continents
ObjectivesDescribe Wegener's hypothesis of continental drift.Explain how seefloor spreading provides a way for continents to
move.Describe how new oceanic lithosphere forms at midocean ridges.Explain how magnetic reversals provide evidence for seafloor
spreading.
Continental DriftWegener’s theory of the movement of the continents
Pangaea "All Earth"Wegener’s theory of one supercontinentSurrounded by one sea called Panthalassa = all sea
Pangaea puzzle
Broke into two partsLaurasiaGondwana
Plate Tectonicstheory of how continents move7 major plates
Evidence that supports Wegener Theory1. Fossils2. Puzzle3. SeaFloor Spreading
deepest known place on Earth = 11,033 m below sea level and 2,500 m long = Mariana Trench
4. Glacier5. Rock6. Magnetic Reversals
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Review Questions
1. What is the difference between Continental Drift and Plate Tectonics?
2. Name the Supercontinent.
3. Name the "One Ocean".
4. List 5 forms of evidence that support Continental Drift.
5. Who developed the Theory of Continental Drift?
6. What were the two pieces that the plates broke into?
7. What is the layer of the Earth that allows the plates to float on it?
8. Draw a diagram of the all the layers of the Earth.
Answers
1. Continental Drift is the belief that the plates move and Plate Tectonics is how they move.
2. Pangaea
3. Panthalassa
4. Puzzles pieces Fossils SeaFloor Spreading Magnetic Reversals Glaciers Rocks
5. Alfred Wegener
6. Northern Laurasia Southern Gondwana
7. Asthenosphere
8.
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Section 3 The Theory of Plate Tectonics
Plate TectonicsThe theory that explains how pieces of the Earth’s crust move and change shape.
What happens when plates move?causes tectonic activitiesearthquakesvolcanoesmountain buildingglacier
BoundaryWhere tectonic plates touch.
3 Types of Boundaries1. Divergent Boundary
plates move apart and magma rises to fill gapMidAtlantic Ridge
2. Convergent Boundary2 plates collide
3 Types of Convergent Boundariesa. Continental Continental
Buckle and thicken which pushes the crust upwardb. Continental Oceanic
Oceanic plate sinks into the lithosphere Subduction Zonec. Oceanic Oceanic
One plate will sink under the other
3. Transform Boundaryplates slide past one another horizontally strike slip faultcauses earthquakes
What is behind all this?Convection current
cycle of heating, rising, cooling and sinking page 204
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Tectonic PlatesPieces of the lithosphere that move ontop of the asthenosphere
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Section 4 Shaping of the Earth’s crust
Deformationprocess by which the rock changes due to stress
Types of stress1. Compression
occurs when an object is squeezedoccurs at convergent boundaries
2. Tensionoccurs when forces are stretchedoccurs at divergent boundaries
Foldingbending of rock layers
1. Anticlinesupward arching folds
2. Synclinesdownward, troughlike folds
3. Monoclinerock layers fold so both ends are horizontal
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Section 4 FaultNormal Faults
hanging wall moves downward according to the footwall caused by tension
Reverse Faults/Thrust Faulthanging wall moves upward according to the footwall
caused by compression
thrust hanging wall may actually go over the footwall
Strikeslip Faults/Lateral Faultsmove in opposition to each othershearing forces help push rocks in opposite directions
MountainsFolded mountains
form at convergent boundarieshighest mountainsides squeezed together and push upward
FaultBlock mountainsform at divergent boundariescaused by rock dropping down according to the pulling
apart of the rock
Volcanic mountainsform at convergent boundaries
near subduction zones
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UpliftRising of Earth's crust to higher elevations
SubsidenceSinking of Earth's crust to lower elevations
Rift ZoneCracks in the Earth's crust due to uplift and subsidence
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How and why plates move
Crust, Mantle, Core
GondwanaLaurasia
NormalBoundary
DivergentBoundary
Convergent Boundary
Squeezing
Uplift
Mantle
Asthenosphere
Tension
fossils, glaciers, rocks, magneticreversals, puzzles
Rift Zones
states the platesmove
Transform
Iron andNickel
Wegener
Lithosphere
Normal Fault
MoreMagnesium
tectonicplates
Panthalassa
Midoceanridges
SubductionZone
Convection Current
Anticlines
Monocline
Synclines
San AndreasFault
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