THE EARTH’S LIFE SUPPORT SYSTEMS

• The biosphere consists of several physical layers that contain:– Air– Water– Soil– Minerals – Life

Figure 3-6Figure 3-6

Biosphere

• Atmosphere– Membrane of air around the planet.

• Stratosphere– Lower portion contains ozone to filter out most

of the sun’s harmful UV radiation.

• Hydrosphere– All the earth’s water: liquid, ice, water vapor

• Lithosphere– The earth’s crust and upper mantle.

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.continents.

EarthEarth

• orbit: 149,600,000 km (1.00 AU) from Sun

• diameter: 12,756.3 km

• mass: 5.972e24 kgmass: 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

GEOLOGIC PROCESSESGEOLOGIC PROCESSES

• Major features of the earth’s crust and upper Major features of the earth’s crust and upper mantle.mantle.

Figure 15-2Figure 15-2

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)

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 rack Huge volumes of heated and molten rack 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.slowly across the earth’s surface.– 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.

The Earth’s Major Tectonic The Earth’s Major Tectonic PlatesPlates

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 plates The extremely slow movements of these plates cause them to grind into one another at 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.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

Animation: Plate MarginsAnimation: Plate Margins

PLAYANIMATION

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 Continental + Continental = Mountain RangeRange

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

Recylcing Earth’s CrustRecylcing Earth’s Crust

• Natural disasters like earthquakes and Natural disasters like earthquakes and volcanoes occur at plate boundariesvolcanoes occur at plate boundaries

• From geologic perspective, however, there are From geologic perspective, however, there are advantages to plate movementadvantages to plate movement– Forms mineral deposits and promotes and Forms mineral deposits and promotes and

sustains lifesustains life– Led to the evolution of life on EarthLed to the evolution of life on Earth– Formed Earth’s primitive atmosphere and Formed Earth’s primitive atmosphere and

therefore climatetherefore climate– Rich soilsRich soils

Geologic Time ScaleGeologic Time Scale

• ~4.6 billion years ago: Earth believed to ~4.6 billion years ago: Earth believed to have formed, hot ball of rockhave formed, 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 Based largely on energy from the sun and

gravitygravity

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

• ErosionErosion• WeatheringWeathering

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

• Weathering Weathering is an is an external external process that process that wears the wears the earth’s 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 loosened or worn away from one part of the earth’s surface and deposited in the earth’s surface and deposited in other placesother 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 inorganic elements and compounds called minerals that can sometimes be called minerals that can sometimes be used as resources.used as 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.

ROCKROCK

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

from sediment of pre-existing rocks that are from sediment of pre-existing rocks that are weathered and erodedweathered and eroded

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

– Igneous rock (granite, pumice, basalt). Formed from Igneous rock (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

SOIL: A RENEWABLE RESOURCE

• Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth and also helps purify water.– Soil formation begins when bedrock is broken

down by physical, chemical and biological processes called weathering.

• Mature soils, or soils that have developed over a long time are arranged in a series of horizontal layers called soil horizons.

COMPONENTS OF SOIL

Soil Formation:

•Product of weathering

•Function of parent material, climate, topography, organisms, and time

Fig. 3-23, p. 68

Fern

Mature soil

Honey fungus

Root system

Oak tree

Bacteria

Lords and ladies

Fungus

Actinomycetes

Nematode

Pseudoscorpion

Mite

RegolithYoung soil

Immature soil

Bedrock

Rockfragments

Moss and lichen

Organic debrisbuilds upGrasses and

small shrubs

Mole

Dog violet

Woodsorrel

EarthwormMillipede

O horizonLeaf litter

A horizon

Topsoil

B horizonSubsoil

C horizon

Parent material

Springtail

Red Earth Mite

Animation: Soil Profile

PLAYANIMATION

Layers in Mature Soils

• Infiltration: the downward movement of water through soil.

• Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower layers.

• The soil type determines the degree of infiltration and leaching.

Soil Profiles of the Principal

Terrestrial Soil Types

Figure 3-24Figure 3-24

Fig. 3-24a, p. 69

Mosaic of closely packed pebbles, boulders

Weak humus-mineral mixture

Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts

Alkaline, dark, and rich in humus

Clay, calcium compounds

Desert Soil(hot, dry climate)

Grassland Soilsemiarid climate)

Fig. 3-24b, p. 69

Tropical Rain Forest Soil(humid, tropical climate)

Acidic light-colored humus

Iron and aluminum compounds mixed with clay

Fig. 3-24b, p. 69

Deciduous Forest Soil(humid, mild climate)

Forest litter leaf moldHumus-mineral mixtureLight, grayish-brown, silt loamDark brown firm clay

Fig. 3-24b, p. 69

Coniferous Forest Soil(humid, cold climate)

Light-colored and acidic

Acid litter and humus

Humus and iron and aluminum compounds

Soil Properties

• Soils vary in the size of the particles they contain, the amount of space between these particles, and how rapidly water flows through them.

Figure 3-25Figure 3-25

Atmosphere• Thin layer of gases that surrounds the Earth• Composed of:

– Nitrogen– Oxygen– Water vapor– Argon– Carbon dioxide– Neon– Helium– Other

Atmosphere has changed

• Early Earth’s atmosphere consisted only of methane, water vapor, ammonia and hydrogen

• Photosynthesis greatly changed our atmosphere!

Five Layers

Troposphere• Earth’s surface to ~ 6 miles

above the surface

• Contains ~ 90% of atmospheric gases

• Where weather occurs

Stratosphere• 6 miles to about 30 miles

above Earth’s surface

• Air is less dense

• Less turbulent air flow

• Contains the ozone layer

Mesosphere, Thermosphere,

Exosphere• Gases become thinner and

thinner

• Colder and colder

• Exosphere merges with outer space