Geology ConceptsGeology Concepts

Mr. Clark

BHS

Key ConceptsKey Concepts

Major geologic processes Major geologic processes

Minerals, rocks, and the rock cycle Minerals, rocks, and the rock cycle

Earthquakes and volcanoes Earthquakes and volcanoes

Plate Tectonics Plate Tectonics

Structure of the EarthStructure of the Earth

Features of the Crust and Upper MantleFeatures of the Crust and Upper Mantle

External Earth ProcessesExternal Earth Processes

Erosion Erosion

Mechanical weatheringMechanical weathering

Frost wedgingFrost wedging

Chemical weatheringChemical weathering

Biological weatheringBiological weathering

Natural Hazards: EarthquakesNatural Hazards: Earthquakes

Features Features

Magnitude Magnitude

Aftershocks Aftershocks

Primary effects Primary effects

Secondary effects Secondary effects

Expected Earthquake DamageExpected Earthquake Damage

CanadaCanada

United StatesUnited States

No damage expectedNo damage expected

Minimal damageMinimal damage

Moderate damageModerate damage

Severe damageSevere damage

Natural Hazards: Volcanic EruptionsNatural Hazards: Volcanic Eruptions

extinctvolcanoes

extinctvolcanoes

magmareservoir

centralvent

magmaconduit

SolidlithosphereSolidlithosphere

Upwellingmagma

Partially moltenasthenosphere

Minerals and RocksMinerals and Rocks

Mineral (diamond, quartz)Mineral (diamond, quartz)

Rock TypesRock Types

Igneous (granite, basalt)Igneous (granite, basalt)

Sedimentary (limestone, sandstone)Sedimentary (limestone, sandstone)

Metamorphic (marble, slate)Metamorphic (marble, slate)

Igneous RockGranite, Pumice,

Basalt

Sedimentary RockShale, Sandstone,

Limestone

Metamorphic RockSlate, Quartzite,

Marble

Magma(Molten Rock)

WeatheringWeathering

ErosionErosion

TransportTransportDepositionDeposition

Heat,Pressure

Heat,Pressure

Heat,

Pressure

Heat,

Pressure

Rock Cycle

Oceanic crust(lithosphere)

Abyssalhills Abyssal

floorOceanic

ridgeTrench

Volcanoes

Folded mountain belt

Craton

Mantle (lithosphere)

Mantle (asthenosphere)

Ab

ys

sa

l p

lain

Continental crust(lithosphere)

Mantle(lithosphere)

Continentalrise

Continentalslope

Continentalshelf

Abyssal plain

Abyssalfloor

Tectonic plate

Collision between two continents

Oceanic tectonicplate

Spreading center Oceanic tectonic

plateOcean trench

Plate movement Plate movement

Continentalcrust

Subductionzone

Oceaniccrust

Oceaniccrust

Continentalcrust

Mantle

Innercore

Hot outercore

Two plates movetowards each other.One is subductedback into the mantleon falling convectioncurrent.

Mantleconvectioncell

Hot materialrisingthroughthe mantle

Material coolsas it reachesthe outer mantle

Cold densematerial fallsback throughmantle

EURASIAN PLATE

CHINASUBPLATE PHILIPPINE

PLATE

INDIAN-AUSTRLIAN PLATE

PACIFICPLATE

JUAN DEFUCA PLATE

COCOSPLATE

CARIBBEAN PLATE

NORTHAMERICAN

PLATE

SOUTHAMERICAN

PLATE

EURASIAN PLATE

ANATOLIAN PLATE

ARABIAN PLATE

AFRICAN PLATE

SOMALIAN SUBPLATE

CarlsbergRidge

Southwest IndianOcean Ridge

ANTARCTIC PLATE

Transformfault

East PacificRise

Transformfault

Mid-IndianOceanRidge

Southeast IndianOcean Ridge

Mid-AtlanticOceanRidge

ReykjanesRidge

Transformfault

Divergent ( ) andtransform fault ( )boundaries

Convergentplate boundaries

Plate motionat convergentplate boundaries

Plate motionat divergentplate boundaries

Click to view animation.

AnimationAnimation

Plate margins interaction.

Lithosphere

Asthenosphere

Oceanic ridge at a divergent plate boundary

Divergent BoundaryDivergent Boundary

Lithosphere

Trench Volcanic island arc

Asthenosphere

Risingmagma

Subductionzone

Trench and volcanic island arc at a convergentplate boundary

Convergent BoundaryConvergent Boundary

Fracture zone

Transformfault

Lithosphere

Asthenosphere

Transform fault connecting two divergent plate boundaries

Liquefaction ofrecent sedimentscauses buildingsto sink

Landslides mayoccur onhilly ground

Shockwaves

Epicenter

Focus

Two adjoining platesmove laterally alongthe fault line

Earth movementscause flooding inlow-lying areas

Canada

United States

No damage expected

Minimal damage

Moderate damage

Severe damage

extinctvolcanoes

magmareservoir

centralvent

magmaconduit

Solidlithosphere

Upwellingmagma

Partially moltenasthenosphere

Igneous RockGranite,pumice,basalt

Metamorphic RockSlate, marble,quartzite

Magma(molten rock)

Heat, pressure, stress

Heat, pressure

Melting

Sedimentary RockShale, sandstone,

limestone

Deposition

Transportation

Erosion

Weathering

White clam

Magma

Black smoker

Sulfidedeposit

White crab

Tube worms

Whitesmoker

Geologic Time ScaleGeologic Time Scale

Because fossils appeared in a predictable order, one can use them as relative time markers.

What’s more you can define time periods based on certain fossils that were living at that time.

This enabled geologists to construct the Geologic Time Scale and name its periods based on the fossil record.

Plate TectonicsPlate Tectonics

Divergent boundaryDivergent boundary

Convergent boundaryConvergent boundary

Subduction zoneSubduction zone

Transform faultTransform fault

Earth’s Major Tectonic PlatesEarth’s Major Tectonic Plates

Plate TectonicsPlate Tectonics

Plate Tectonics: FundamentalsPlate Tectonics: Fundamentals• Evidence - plate tectonics unites many

disparate observations

• Sea-floor spreading - the oceans widening is the mechanism that moves the continents

Plate Tectonics: FundamentalsPlate Tectonics: Fundamentals• Plate margins - convergent, divergent,

transform

• Continental crust vs. oceanic crust

• The Earth’s interior: lithosphere, mantle, core

http://imiloa.wcc.hawaii.edu/krupp/BIOL101/present/lcture18/img009.jpg

Continental DriftContinental Drift

Alfred Wegener(1880-1930)

Wegener’s versionof continental drift(1912)

Wegener was correct…but he had no mechanism.

Plate Tectonics - 1960sPlate Tectonics - 1960s

• New data:

– the age of the ocean floor

– magnetic stripes

Magnetic Stripes and Seafloor Spreading

Magnetic Stripes and Seafloor Spreading

Magnetic Stripes and Seafloor Spreading

http://jove.geol.niu.edu/faculty/fischer/105_info/105_E_notes/lecture_notes/Plate_Tectonics/PT_images/magnetic_stripes_form.gif

Seafloor SpreadingSeafloor Spreading

How doesseafloor spreadinglead to continentalbreakup?

http://www.ac.wwu.edu/~debari/406/figs/divergent.jpeg

Plate MarginsPlate Margins

http://earth.geol.ksu.edu/sgao/g100/plots/1203_03_plate.jpg

Transform faultplate boundaries

Continental vs. Oceanic CrustContinental vs. Oceanic Crust

Oceanic vs. Continental CrustOceanic vs. Continental Crust Age:

OC = <180 m.y.a.

CC = 2-3 b.y.a.

Thickness:

OC = 5-7 kilometers thick

CC = 10-70 km

Oceanic vs. Continental CrustOceanic vs. Continental Crust Composition:

OC = basaltic

CC = granitic

Density:

OC = 3.0 grams per cubic centimeter

CC = 2.7 gm/cc

The Earth’s Interior

We know the Earth is layered because of seismic wave data!

The Earth’s interiorThe Earth’s interior

• Composition:

– Crust – mafic / felsic

– Mantle - ultramafic

The Earth’s interior: 2 bases for layeringThe Earth’s interior: 2 bases for layering

• Viscosity/Velocity:– Lithosphere - rigid & non- flowable, 0-150km– Asthenosphere - soft & flowable, 150-400 km

( “upper mantle”)– Mantle

• - transition zone (400-670 km)

• - lower mantle (670-2900 km)

– Core

Mantle Convection: the mechanism for plate tectonics?

Plate tectonics explains things, for example...Plate tectonics explains things, for example...

• Mountain belts

• The Hawaiian islands