Scientific MethodScientific Method

Observations

Data Collection

Interpretation

Hypothesis

Explanation

(or conclusion)

Scientific MethodScientific Method

Observations

Data Collection

Interpretation

Hypothesis

Explanation

(or conclusion)

Theory

Earth SpheresEarth Spheresandand

Plate TectonicsPlate Tectonics

Earth SpheresEarth Spheres

GeosphereHydrosphereAtmosphereBiosphere

01.03.a

Thickest Thickest layer: layer: mantlemantle

Upper layer is Upper layer is crustcrust; ; two types:two types: continentalcontinental oceanicoceanic

Lowest layer: iron-nickel Lowest layer: iron-nickel core (molten outer core; core (molten outer core; solid inner core)solid inner core)

• Outermost layer• solid, rigid rock (and sediment, soil)

continental: 20 – 40 km thicklight-colored, low density granite

oceanic: 4 – 7 km thickdark, dense basalt

Earth’s Crust

01.03.b1

Some Layers Are Stronger than OthersSome Layers Are Stronger than Others

Oceanic crustOceanic crust

Continental crustContinental crust

Uppermost mantleUppermost mantle

Lithosphere Lithosphere (stronger)(stronger)

Asthenosphere (weaker)Asthenosphere (weaker)

Asthenosphere: hot and weak; mostly solidAsthenosphere: hot and weak; mostly solid

• Lithosphere:Crust + upper portion of mantlerigid, strong rockbroken into pieces plates

• Asthenosphere(upper) mid-mantle: solid, weak

behaves like plastic 1-2% molten

Result: plates “float” (move) on the asthenosphere.

Lithosphere & Asthenosphere

01.03.c1

Why Are Some Regions High In Elevation?Why Are Some Regions High In Elevation?

Regions with Regions with thick crust thick crust higher than thin higher than thin crustcrust

Regions with continental Regions with continental crust higher than oceanic crust higher than oceanic crustcrust

Some mountains built Some mountains built on top of cruston top of crust

01.03.m1Dense materials are lower

Thick blocks higher than thin blocks

Relationship between crustal thicknessand elevation: isostasy

Why Are Some Regions HigherIn Elevation than Others?

03.07.b1

Lithospheric PlatesLithospheric Plates

01.03.a

Thickest Thickest layer: layer: mantlemantle

Lowest layer: iron-nickel Lowest layer: iron-nickel corecore (molten outer core; (molten outer core; solid inner core)solid inner core)

Evidence for what is beneath the crust… Evidence for what is beneath the crust…

Planet’s densityPlanet’s density Interior is more dense than basalt and graniteInterior is more dense than basalt and granite

VolcanoesVolcanoes Not completely solid, pieces of “mantle”Not completely solid, pieces of “mantle”

DiamondsDiamonds High pressure High pressure

Seismic InformationSeismic Information layers with different physical and chemical layers with different physical and chemical

propertiesproperties

W. W. NortonW. W. Norton

Crust

Mantle

Moho

6400 km

Asthenosphere

Lithosphere

Earth’s Mantle

• Immediately beneath crust• 2900 km thick• 80% Earth’s volume• Dark, dense peridotite (denser than crustal rocks)• Three major portions

upper portion: solid, strong, rigid rock (part of lithosphere)asthenosphere: solid, weak (behaves like plastic)

1-2% moltendeeper portion: solid, strong, rigid rock

Earth’s Mantle

6000 degrees CMetal (Fe, Ni) •Outer Core:

liquid 2250 km thick

• Inner Core:solid1220 km thick

Earth’s Core Crust

Mantle

Core

Moho

Earth SpheresEarth Spheres

GeosphereHydrosphereAtmosphereBiosphere

01.07.a1

Glaciers

Clouds and precipitationClouds and precipitation

Flowing water

OceanOceancurrentscurrents

LakesLakesGroundwaterGroundwater

Oceans97.5%

1.8%

0.63%

0.01%

0.001%

HydrosphereHydrosphere

Earth SpheresEarth Spheres

GeosphereHydrosphereAtmosphereBiosphere

Mixture of gasesMixture of gases 79% nitrogen79% nitrogen 21% oxygen21% oxygen argon argon carbon dioxide carbon dioxide othersothers

AtmosphereAtmosphere

01.07.b1

PrecipitationPrecipitation

Water vaporWater vapor

WindWind

EvaporationEvaporation

Atmosphere Atmosphere blocks some light blocks some light and UVand UV

EnergyEnergy converted to converted to infrared infrared

Land and sea Land and sea absorb heatabsorb heat

Driving Mechanisms of Spheres?Driving Mechanisms of Spheres?

Solar RadiationSolar Radiation BiosphereBiosphere AtmosphereAtmosphere HydrosphereHydrosphere

Heat of Formation + Radioactive DecayHeat of Formation + Radioactive Decay GeosphereGeosphere

Plate TectonicsPlate Tectonicsthe processes and landforms the processes and landforms

resulting from the movement of resulting from the movement of lithospheric plateslithospheric plates

03.07.a1

What Moves the Plates?What Moves the Plates?

Ridge pushRidge push

Slab pullSlab pull Other forces, such as Other forces, such as convection in mantleconvection in mantle

Driving Mechanism of GeosphereDriving Mechanism of Geosphere

Mantle Convection

03.03.b1-3

Three Types of Relative Plate MotionsThree Types of Relative Plate MotionsMove apart: Move apart: divergent boundarydivergent boundary

Move toward each other: Move toward each other: conconvergent boundaryvergent boundary

Move horizontally Move horizontally past one another: past one another: transform boundarytransform boundary

03.03.c1

Observe the locations of different types of plate boundariesObserve the locations of different types of plate boundaries

03.04.a1-2

Oceanic Divergent BoundariesOceanic Divergent Boundaries

Oceanic plates Oceanic plates move apart at move apart at mid-ocean ridges mid-ocean ridges (seafloor (seafloor spreading)spreading)

Forms new Forms new oceanic crustoceanic crust

Mid-Atlantic Mid-Atlantic RidgeRidge

03.04.a

Magma rises Magma rises through fracturesthrough fractures

Narrow trough, or Narrow trough, or riftrift

Asthenosphere Asthenosphere rises and meltsrises and melts

Magma erupts Magma erupts or solidifies at or solidifies at depth; forms depth; forms new oceanic new oceanic crustcrust

Ridge high (hot rocks and Ridge high (hot rocks and thin lithosphere)thin lithosphere)

Features and Processes of Mid-Ocean RidgesFeatures and Processes of Mid-Ocean Ridges

03.04.b1-4

Observe what happens when continents rift apartObserve what happens when continents rift apart

Stretching and faulting form rift Stretching and faulting form rift

Initial uplift from rising mantleInitial uplift from rising mantle

Melting forms magmaMelting forms magma

Can lead to seafloor spreading Can lead to seafloor spreading and new ocean basinand new ocean basin

Ocean widens with spreadingOcean widens with spreading

03.05.a1

Ocean-Ocean Convergent BoundaryOcean-Ocean Convergent Boundary

One plate moves One plate moves down = down = subductionsubduction

Two oceanic plates Two oceanic plates move toward one move toward one anotheranother

Trench and island arcTrench and island arc

03.05.b1

Ocean-Continent Convergent BoundaryOcean-Continent Convergent Boundary

Oceanic plate subducted Oceanic plate subducted beneath continentbeneath continent

Oceanic and continental Oceanic and continental plate convergeplate converge

Overlying mantle Overlying mantle meltedmelted

Volcanoes and squeezing Volcanoes and squeezing form mountain beltform mountain belt

TrenchTrench

03.05.c1

Observe the distribution of volcanoes around the Pacific Ring Observe the distribution of volcanoes around the Pacific Ring of Fire of Fire

What doWhat doyou thinkyou thinkcould could explain explain the the overall overall pattern?pattern?

Pacific Ring of FirePacific Ring of Fire

03.05.c2

Subduction beneath Subduction beneath oceanic plates = oceanic plates = island arcsisland arcs

Oceanic plates subducted Oceanic plates subducted on both sideson both sides

Subduction beneath continental Subduction beneath continental plates = mountain belts with plates = mountain belts with volcanoesvolcanoes

03.05.d1-3

Continent-Continent Continent-Continent ConvergenceConvergence

Subduction Subduction brings continents brings continents closercloser

Subduction Subduction of oceanic of oceanic part of platepart of plate

Continents Continents collidecollide

Two continents collideTwo continents collide

03.05.d3

Pieces sliced offPieces sliced off

Continental collision = wide zone of deformationContinental collision = wide zone of deformation

Continental plate Continental plate buoyant, so buoyant, so subduction endssubduction ends

Few volcanoesFew volcanoes

Thick crust = high elevationThick crust = high elevation

03.07.d1

Transform BoundaryTransform BoundaryObserve how these two plates are moving past each otherObserve how these two plates are moving past each other

Transform Transform boundaries link boundaries link other types of plate other types of plate boundaries, like two boundaries, like two spreading centersspreading centers

Plates move Plates move horizontally past horizontally past one anotherone another

03.06.a1

Transform BoundaryTransform BoundaryObserve how these two “plates” are moving Observe how these two “plates” are moving past each otherpast each other

Link other Link other types of plate types of plate boundariesboundaries

Plates move Plates move horizontally past horizontally past one anotherone another

03.06.a2

Observe the pattern of the Mid-Atlantic RidgeObserve the pattern of the Mid-Atlantic Ridge

TransformsTransforms

Spreading Spreading segmentssegments

03.06.b1

Observe plate boundaries near the west coast of Observe plate boundaries near the west coast of North America (green lines are transform boundaries)North America (green lines are transform boundaries)

03.07.b1

Rates of Relative Plate MovementRates of Relative Plate Movement

Which plate boundaries have the fastest rates?Which plate boundaries have the fastest rates?

Some move faster than othersSome move faster than othersPlates move cm/yearPlates move cm/year

Formation of Linear Island ChainsFormation of Linear Island Chains

Plate moves over a hot spotPlate moves over a hot spot

Lines of islands Lines of islands and seamountsand seamounts

Volcano Volcano forms forms over hot over hot spotspot

Volcanism shuts off Volcanism shuts off as area moves awayas area moves away

Plate subsides Plate subsides as cools, so as cools, so islands become islands become seamountsseamounts

03.08.c

03.08.c

Examples of Linear ChainsExamples of Linear Chains

Pacific OceanPacific Ocean Atlantic OceanAtlantic Ocean

HawaiiHawaii

AfricaAfrica