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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