GEOLOGY and the Rock GEOLOGY and the Rock CycleCycle

GEOLOGIC PROCESSESGEOLOGIC PROCESSES The earth is made up of a core, mantle, and The earth is made up of a core, mantle, and

crust and is constantly changing as a result crust and is constantly changing as a result of processes taking place on and below its of processes taking place on and below its surface.surface.

The earth’s interior consists of:The earth’s interior consists of: CoreCore: innermost zone with solid inner core and : innermost zone with solid inner core and

molten outer core that is extremely hot.molten outer core that is extremely hot. MantleMantle: solid rock, under which is the : solid rock, under which is the

asthenosphere that is melted pliable rock.asthenosphere that is melted pliable rock. CrustCrust: Outermost zone which underlies the : Outermost zone which underlies the

continents. (Lithosphere)continents. (Lithosphere)

Fig. 15-3, p. 337

Spreading center Ocean

trench

Plate movement

Subduction zone

Oceanic crust

Continental crust

Continental crust

Material cools as it reaches

the outer mantle

Cold dense material falls back through

mantleHot

material rising

through the

mantle

Mantle convection

cell

Two plates move towards each other. One is subducted back into the mantle on a falling convection current.

Mantle

Hot outer core Inner

core

Plate movement

Collision between two continents

Tect

onic

pl

ate

Oceanic tectonic

plate

Oceanic tectonic plate

Oceanic crust

INTERNAL GEOLOGIC INTERNAL GEOLOGIC PROCESSESPROCESSES

Huge volumes of heated and molten rock Huge volumes of heated and molten rock moving around the earth’s interior form moving around the earth’s interior form massive solid plates that move extremely massive solid plates that move extremely slowly across the earth’s surface due to slowly across the earth’s surface due to convection currents.convection currents. Tectonic platesTectonic plates: huge rigid plates that are : huge rigid plates that are

moved with convection cells or currents by moved with convection cells or currents by floating on floating on magmamagma or molten rock. or molten rock.

Fig. 15-2, p. 336

Volcanoes

Folded mountain belt

Abyssal floor

Oceanic ridge

Abyssal floor TrenchAbyssal hills

Craton

Abyssal plain

Oceanic crust (lithosphere)

Continental Continental shelfshelf

Aby

ssal

pla

in

Continental slope

Continental rise

Continental crust (lithosphere) Mantle (lithosphere)

Mantle (lithosphere)

Mantle (asthenosphere)

EarthEarth

orbit: 149,600,000 km (1.00 : 149,600,000 km (1.00 AU) from Sun ) from Sun diameter: 12,756.3 km : 12,756.3 km mass: 5.972e24 kg: 5.972e24 kg Earth’s layers (depths in km)Earth’s layers (depths in km)

0- 40 Crust 0- 40 Crust 40- 2890 Mantle 40- 2890 Mantle 2890-5150 Outer core 2890-5150 Outer core 5150-6378 Inner core 5150-6378 Inner core

EarthEarth

Earth’s mass (measured in 10^24 kg)Earth’s mass (measured in 10^24 kg) atmosphere = 0.0000051 atmosphere = 0.0000051 oceans = 0.0014 oceans = 0.0014 crust = 0.026 crust = 0.026 mantle = 4.043 mantle = 4.043 outer core = 1.835 outer core = 1.835 inner core = 0.09675 inner core = 0.09675

Earth’s InteriorEarth’s Interior

Core is made up mostly of iron/nickelCore is made up mostly of iron/nickel Temperatures in core reach 7500 KTemperatures in core reach 7500 K The crust is primarily quartz. The crust is primarily quartz. Taken as a whole, the Earth's chemical Taken as a whole, the Earth's chemical

composition (by mass) is: composition (by mass) is: 34.6% Iron 34.6% Iron 2.4% Nickel 2.4% Nickel 29.5% Oxygen29.5% Oxygen 1.9% Sulfur 1.9% Sulfur 15.2% Silicon 15.2% Silicon 0.05% Titanium0.05% Titanium 12.7% Magnesium 12.7% Magnesium

The Earth’s Major Tectonic PlatesThe Earth’s Major Tectonic Plates

Figure 15-4Figure 15-4

Major PlatesMajor Plates

North American Plate North American Plate South American PlateSouth American Plate Antarctic PlateAntarctic Plate Eurasian PlateEurasian Plate African PlateAfrican Plate Indian-Australian PlateIndian-Australian Plate Nazca PlateNazca Plate Pacific PlatePacific Plate

Plate MovementPlate Movement

The extremely slow movements of these The extremely slow movements of these plates cause them to grind into one another plates cause them to grind into one another at convergent plate boundaries, move apart at convergent plate boundaries, move apart at divergent plate boundaries and slide past at divergent plate boundaries and slide past at transform plate boundaries.at transform plate boundaries.

Figure 15-4Figure 15-4

Fig. 15-4, p. 338

Fig. 15-4a, p. 338

EURASIAN PLATEEURASIAN PLATENORTH NORTH AMERICAN AMERICAN PLATEPLATE

ANATOLIAN ANATOLIAN PLATEPLATE

JUAN DE JUAN DE FUCA PLATEFUCA PLATE

CHINA CHINA SUBPLATESUBPLATE

CARIBBEAN CARIBBEAN PLATEPLATE

PHILIPPINE PHILIPPINE PLATEPLATE

ARABIAN ARABIAN PLATEPLATEAFRICAN AFRICAN

PLATEPLATEPACIFIC PACIFIC PLATEPLATE SOUTH SOUTH

AMERICAN AMERICAN PLATEPLATENAZCA NAZCA

PLATEPLATEINDIA-INDIA-

AUSTRALIAN AUSTRALIAN PLATEPLATE

SOMALIAN SOMALIAN SUBPLATESUBPLATE

ANTARCTIC PLATEANTARCTIC PLATE

Divergent plate boundaries

Convergent plate boundaries

Transform faults

Fig. 15-4b, p. 338

Trench Volcanic island arc Craton

Transform fault

LithosphereSubduction zone

Lithosphere Lithosphere

Asthenosphere Asthenosphere Asthenosphere

Divergent plate boundaries Convergent plate boundaries Transform faults

Rising magma

Convergent Plate BoundaryConvergent Plate Boundary

Two plates pushed togetherTwo plates pushed together Oceanic + Continental = Subduction ZoneOceanic + Continental = Subduction Zone Oceanic + Oceanic = TrenchOceanic + Oceanic = Trench Continental + Continental = Mountain RangeContinental + Continental = Mountain Range

Divergent Plate BoundaryDivergent Plate Boundary

Plates moves apart from one anotherPlates moves apart from one another Oceanic plates form oceanic ridgesOceanic plates form oceanic ridges

Transform FaultsTransform Faults

Plates slide and grind past one another along Plates slide and grind past one another along a fracture in the lithospherea fracture in the lithosphere

Benefits of volcanoes, earthquakes, Benefits of volcanoes, earthquakes, and tsunamisand tsunamis

Geological: Geological: Recycle rock and earth’s crustRecycle rock and earth’s crust Form mineralsForm minerals

Ecological:Ecological: Speciation (due to isolation)Speciation (due to isolation) Maintaining atmosphere thus climateMaintaining atmosphere thus climate Enrich soils = more foodEnrich soils = more food

Geologic Time ScaleGeologic Time Scale

~4.6 billion years ago: Earth believed to have ~4.6 billion years ago: Earth believed to have formed, hot ball of rockformed, hot ball of rock

3.9 billion years ago: rainstorms3.9 billion years ago: rainstorms 3.5 billion years ago: oceans, first living 3.5 billion years ago: oceans, first living

organismsorganisms

Geologic ErasGeologic Eras Precambrian Era:Precambrian Era: 4.6 billion years ago- 545 million years ago 4.6 billion years ago- 545 million years ago

87% of Earth’s history87% of Earth’s history Prokaryotes dominated Prokaryotes dominated First eukaryotes appeared ~ 1.5 billion years agoFirst eukaryotes appeared ~ 1.5 billion years ago Simple multicellular organisms in seasSimple multicellular organisms in seas

Paleozoic Era:Paleozoic Era: 545 million years ago – 248 million years ago 545 million years ago – 248 million years ago ““Explosion of life”Explosion of life” Many types of invertebrates in shallow seasMany types of invertebrates in shallow seas Early: earliest vertebratesEarly: earliest vertebrates Middle: amphibiansMiddle: amphibians Later: reptilesLater: reptiles

Geologic ErasGeologic Eras

Mesozoic Era:Mesozoic Era: 248 million years ago – 65 million years ago 248 million years ago – 65 million years ago Triassic: mammals made first appearanceTriassic: mammals made first appearance Jurassic: “age of dinosaurs”Jurassic: “age of dinosaurs” Cretaceous: radiation of mammals and evolution of Cretaceous: radiation of mammals and evolution of

flowering plantsflowering plants Plate Tectonics: continental shiftPlate Tectonics: continental shift

Cenozoic Era:Cenozoic Era: 65 million years ago – now 65 million years ago – now Mammals flourishMammals flourish Primates evolvePrimates evolve Extinctions affect diversityExtinctions affect diversity Modern human species evolved ~200,000 years agoModern human species evolved ~200,000 years ago

EXTERNAL GEOLOGIC EXTERNAL GEOLOGIC PROCESSESPROCESSES

Surface processesSurface processes Based largely on energy from the sun and gravityBased largely on energy from the sun and gravity

Tends to wear down Earth’s surface and Tends to wear down Earth’s surface and produce a variety of landforms by the buildup produce a variety of landforms by the buildup of eroded sedimentof eroded sediment

ErosionErosion WeatheringWeathering

Wearing Down and Building Up the Wearing Down and Building Up the Earth’s SurfaceEarth’s Surface

Weathering Weathering is an is an external external process process that wears that wears the earth’s the earth’s surface surface down.down.

Figure 15-6Figure 15-6

EROSIONEROSION

Process by which material is dissolved, Process by which material is dissolved, loosened or worn away from one part of the loosened or worn away from one part of the earth’s surface and deposited in other placesearth’s surface and deposited in other places

Streams are most important agents of Streams are most important agents of erosionerosion

MINERALS, ROCKS, AND THE MINERALS, ROCKS, AND THE ROCK CYCLEROCK CYCLE

The earth’s crust consists of solid The earth’s crust consists of solid inorganic elements and compounds called inorganic elements and compounds called mineralsminerals that can sometimes be used as that can sometimes be used as resources.resources. Mineral resourceMineral resource: is a concentration of : is a concentration of

naturally occurring material in or on the naturally occurring material in or on the earth’s crust that can be extracted and earth’s crust that can be extracted and processed into useful materials at an processed into useful materials at an affordable cost.affordable cost.

Nonrenewable mineral resourcesNonrenewable mineral resources

Fossil fuels (oil, natural gas, coal)Fossil fuels (oil, natural gas, coal) Metallic minerals (Al, Cu, Fe)Metallic minerals (Al, Cu, Fe) Nonmetallic minerals (sand, gravel, Nonmetallic minerals (sand, gravel,

limestone)limestone)

Minerals and their UsesMinerals and their Uses

Metals Metals Al- building, cansAl- building, cans Steel- buildingSteel- building Cu- conductor, Cu- conductor,

electronicselectronics Mn, Co, Cr- used in alloysMn, Co, Cr- used in alloys Pt- catalytic convertersPt- catalytic converters

NonmetalsNonmetals Sand- glass, concrete, Sand- glass, concrete,

bricksbricks Gravel- roadbedsGravel- roadbeds Limestone- roadbeds, Limestone- roadbeds,

natural buffernatural buffer Phosphate salts- Phosphate salts-

fertilizersfertilizers

US consumptionUS consumption

8% of world population but use 75% of 8% of world population but use 75% of metals on earthmetals on earth Uses: cars, engines, appliances, weapons, Uses: cars, engines, appliances, weapons,

satellitessatellites

ROCKROCK

A very slow chemical cycle recycles three types of A very slow chemical cycle recycles three types of rock found in the earth’s crust:rock found in the earth’s crust: Sedimentary rock Sedimentary rock (sandstone, limestone). Formed from (sandstone, limestone). Formed from

sediment of pre-existing rocks that are weathered and sediment of pre-existing rocks that are weathered and erodederoded

Metamorphic rock Metamorphic rock (slate, marble, quartzite). Formed (slate, marble, quartzite). Formed when pre-existing rock is subjected to high temperatures when pre-existing rock is subjected to high temperatures or pressureor pressure

Igneous rock Igneous rock (granite, pumice, basalt). Formed from (granite, pumice, basalt). Formed from cooled magma at or below earth’s surfacecooled magma at or below earth’s surface

Fig. 15-8, p. 343

Erosion

Transportation

Weathering

Deposition

Igneous rock Granite, pumice, basalt

Sedimentary rock Sandstone, limestone

Heat, pressure

Cooling

Heat, pressure, stress

Magma (molten rock)

Melting

Metamorphic rock Slate, marble, gneiss, quartzite