geology: processes, hazards, and soils chapter 10 g. tyler miller’s living in the environment 13...
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Geology: Processes, Hazards, and Soils
Geology: Processes, Hazards, and Soils
Chapter 10
G. Tyler Miller’sLiving in the Environment
13th Edition
Chapter 10
G. Tyler Miller’sLiving in the Environment
13th Edition
Geologic StructureGeologic Structure
Earth’s internal structur
e
Earth’s internal structur
e
Fig. 10-2 p. 204Fig. 10-2 p. 204
Structure of EarthStructure of Earth
Structure of EarthStructure of Earth• Inner Core/Outer Core – Inner Core/Outer Core –
magma/molten rock with intensely magma/molten rock with intensely hot metals, mostly Fehot metals, mostly Fe
• Mantle – pliable, hot enough to bend Mantle – pliable, hot enough to bend like taffy, less dense than core as it like taffy, less dense than core as it contains lighter elements (Ocontains lighter elements (O22, Si, Mg), Si, Mg)
• Crust – floats atop mantle, consisting Crust – floats atop mantle, consisting of oceanic and continental crustof oceanic and continental crust
Hard Boiled EggHard Boiled Egg
Eight Most Common Chemical Elements (%)Eight Most Common
Chemical Elements (%)WHOLE EARTHWHOLE EARTH CRUSTCRUST
IronIron 33.333.3 OxygenOxygen 45.245.2
OxygenOxygen 29.829.8 SiliconSilicon 27.227.2
SiliconSilicon 15.615.6 AluminumAluminum 8.28.2
MagnesiumMagnesium 13.913.9 IronIron 5.85.8
NickelNickel 2.02.0 CalciumCalcium 5.15.1
CalciumCalcium 1.81.8 MagnesiumMagnesium 2.82.8
AluminumAluminum 1.51.5 SodiumSodium 2.32.3
SodiumSodium 0.20.2 PotassiumPotassium 1.71.7
Features of the CrustFeatures of the Crust
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
Lithosphere = oceanic + continental crust
Asthenosphere = mantle
Internal Earth ProcessesInternal Earth Processes
• Geological changes originating from the Geological changes originating from the earthearth’’s interiors interior– Residual heat from the earthResidual heat from the earth’’s cores core– Radioactive decay in the earthRadioactive decay in the earth’’s crusts crust
• Convection cellsConvection cells• Mantle plumesMantle plumes
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
Plate Tectonics p. 208Plate Tectonics p. 208• Theory explaining the movement of
tectonic plates and the processes that occur at their boundaries.– more commonly referred to as
“continental drift” theory– Plates slide across surface of Earth and
can break or collide– Plate Boundary = area where two
plates meet
EURASIAN PLATEEURASIAN PLATE
CHINACHINASUBPLATESUBPLATE PHILIPPINEPHILIPPINE
PLATEPLATE
INDIAN-AUSTRLIAN PLATEINDIAN-AUSTRLIAN PLATE
PACIFICPLATE
JUAN DEJUAN DEFUCA PLATEFUCA PLATE
COCOSPLATE
CARIBBEANCARIBBEAN PLATEPLATE
NORTHNORTHAMERICANAMERICAN
PLATEPLATE
SOUTHSOUTHAMERICANAMERICAN
PLATEPLATE
EURASIANEURASIAN PLATEPLATE
ANATOLIANANATOLIAN PLATEPLATE
ARABIANARABIAN PLATEPLATE
AFRICANAFRICAN PLATEPLATE
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
Tectonic Plate BoundariesTectonic Plate Boundaries
Divergent boundary
Divergent boundary
Convergent boundary•Subduction zone
Convergent boundary•Subduction zone
Transform fault
Transform fault
LithosphereLithosphere
AsthenosphereAsthenosphere
Plates move apart, forms as mantle magma forms oceanic crust, occurs along ocean basins
EX: Mid Atlantic Ridge, East Pacific Rise
Divergent BoundaryDivergent Boundary
LithosphereLithosphere
Trench Volcanic island arc
AsthenosphereAsthenosphere
RisingRisingmagmamagma
SubductionSubductionzonezone
Convergent BoundaryConvergent Boundary
Plates collide, resulting in subduction OR mtn building, occurs at plate boundaries
EX: Indian Plate, Western South America
Transformfault
LithosphereLithosphere
AsthenosphereAsthenosphere
Transform Faults
Plates slide past each other in opposite but parallel directions, occurs along Fault Lines
EX: San Andreas Fault
Volcanoes Earthquakes
Ring of Fire
Natural Hazards: EarthquakesNatural Hazards: Earthquakes• FeaturesFeatures
– Shock wavesShock waves– Focus and epicenterFocus and epicenter
• MagnitudeMagnitude– Richter ScaleRichter Scale– 1 (insignificant) to 1 (insignificant) to 9 (great) 10X9 (great) 10X
• AftershocksAftershocks• Primary EffectsPrimary Effects
– shakingshaking
• Secondary EffectsSecondary Effects– Rockslides, fires, and floodingRockslides, fires, and flooding– tsunamistsunamis
Expected Earthquake DamageExpected Earthquake Damage
Fig. 10-10 p. 211Fig. 10-10 p. 211
CanadaCanada
United StatesUnited States
No damage expectedNo damage expected
Minimal damageMinimal damage
Moderate damageModerate damage
Severe damageSevere damage
Natural Hazards: Volcanic LocationsNatural Hazards: Volcanic Locations• Volcanic Eruptions occurs at three
geographic locations p. 207
1. Subduction Zones = Pacific Basin Ring of Fire
2. Spreading Centers (Ocean Ridges) = Iceland
3. Hot Spots = rising plume of magma that flowed from crack in crust, Hawaiian Islands
Natural Hazards: Volcanic EruptionsNatural Hazards: Volcanic Eruptions
• Ejecta (rock and ash)
• Molten lava
• Gases
extinctvolcanoes
extinctvolcanoes
magmareservoir
centralvent
magmaconduit
SolidlithosphereSolidlithosphere
Upwellingmagma
Partially moltenasthenosphere
ROCK CYCLE REVIEWROCK CYCLE REVIEW
Rock CycleRock Cycle• Cycle of creation, destruction, and
metamorphosis.– Three major rock classifications:
•IgneousIgneous•SedimentarySedimentary•MetamorphicMetamorphic
Minerals and RocksMinerals and Rocks
• MineralsMinerals– Naturally occurringNaturally occurring– Crystalline structureCrystalline structure– InorganicInorganic– SolidSolid
• Rocks – solid, cohesive, aggregate of one Rocks – solid, cohesive, aggregate of one or more crystalline mineralsor more crystalline minerals– Igneous (granite, lava)Igneous (granite, lava)– 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
ErosionErosionTransportTransport
DepositionDeposition
Internal ProcessesInternal Processes
External ProcessesExternal ProcessesHeat,Heat,
PressurePressure
Heat,Heat,
PressurePressure
LithificationLithification
External Earth ProcessesExternal Earth Processes
• Weathering – breakdown of solid rockWeathering – breakdown of solid rock– Mechanical (physical) weatheringMechanical (physical) weathering
• Frost wedging, freeze thaw cycleFrost wedging, freeze thaw cycle– Chemical weatheringChemical weathering
• Oxidation (losing or gaining of electrons)Oxidation (losing or gaining of electrons)• Hydrolysis (splitting of water)Hydrolysis (splitting of water)
• Erosion – process by which earth Erosion – process by which earth particles are moved from one place particles are moved from one place and deposited in anotherand deposited in another– WindWind– WaterWater– IceIce– GravityGravity
Dunes Lagoon
SpitsStream
Glacier
Lake
Tidalflat
Barrierislands
Shallow marineenvironment
Volcanicisland
Coral reef
Abyssal plain
Deep-sea fan
Continental shelf
Continental slope
Continental rise
DeltaDunes
Beach
Shallow marineenvironment
Landforms resulting from Landforms resulting from external processesprocesses
SoilSoil• Complex mixture of …
– eroded rock– mineral nutrients– decaying organic matter– water– air– micro-organisms
• Renewable resource– Weathering of rocks– Sedimentation– Decomposition of organic matter
What is soil?What is soil?• Mixture of :
– Minerals – weathered rock, essential nutrients– Water – trapped in pore spaces, responsible for leaching
or illuviation– Gases – located in pore spaces– Humus – dead “stuff”, decaying organic materials
thanks to fungi and decomposers, Leaf Litter
Humus NOT HUMMUS Humus NOT HUMMUS
Soil CompositionSoil Composition
Soils: FormationSoils: Formation• Soils form as parent rock material is weathered
(broken down) into smaller pieces via chemical or mechanical weathering– Chemical : lichens excreting acids that break apart rock– Physical: physical forces, freeze/thaw cycles, critters,
biological activity
Soils: Formation p. 212, 215Soils: Formation p. 212, 215
Soil horizons Soil horizons Distinctive layers Distinctive layers
O horizonLeaf litter, organic
A horizonTopsoil
C horizonWeathered Parent
MaterialMature soil
Young soil
RegolithRegolith
BedrockBedrock
Immature soilImmature soil
Humus
B horizonSubsoil, clay/cations leached from above
accumulate here
Weak humus-mineral mixture
Mosaicof closelypackedpebbles,boulders
Dry, brown toreddish-brown, with variable accumulationsof clay, calciumcarbonate, andsoluble salts
Desert Soil(hot, dry climate)
Grassland Soil(semiarid climate)
Alkaline,dark,and richin humus
Clay,calciumcompounds
Acidiclight-coloredhumus
Iron andaluminumcompoundsmixed withclay
Forest litterleaf mold
Humus-mineralmixture
Light, grayish-brown, silt loam
Dark brownFirm clay
Acid litterand humus
Humus andiron andaluminumcompounds
Light-coloredand acidic
Tropical Rain Forest Soil(humid, tropical climate)
Deciduous Forest Soil(humid, mild climate)
Coniferous Forest Soil(humid, cold climate)
Soil Organisms
Provide ecosystem services:-Maintain soil fertility-Cycle organic matter (nutrients)-Break down toxins (bioremediation)-Clean water as it percolates down
Soil PropertiesSoil Properties
Infiltration
Infiltration Leaching
Leaching
Porosity Porosity
Water Water
High permeability Low permeability
Permeability
Porosity vs. PermeabilityPorosity vs. Permeability
Porosity : amount of pore space, # of pores
Porosity : amount of pore space, # of pores
Permeability : ability to transmit fluids
Permeability : ability to transmit fluids
Water Water
High permeability Low permeability
CLAYS:High porosityImpermeable
SANDS:Low porosityPermeable
Soil PropertiesSoil Properties
1. Texture : the way the soil feels
Depends on amount of each
sized particles termed soil fraction
Sand-largest-feel gritty Silt-medium-feel soft, silky,
floury Clay-small-feel sticky, hard to
squeeze, greatest surface area
1. Texture : the way the soil feels
Depends on amount of each
sized particles termed soil fraction
Sand-largest-feel gritty Silt-medium-feel soft, silky,
floury Clay-small-feel sticky, hard to
squeeze, greatest surface area
Soil PropertiesSoil Properties
1. Texture 1. Texture
Structure: % clay, % sand, % silt Structure: % clay, % sand, % silt
100%clay
Increasingpercentage silt
Increasingpercentage clay
0
20
40
60
80
80
60
40
20
0
100%sand80 60 40 20
100%silt
Increasing percentage sand
100%clay
Increasingpercentage silt
Increasingpercentage clay
0
20
40
60
80
80
60
40
20
0
100%sand 80 60 40 20 100%silt
Increasing percentage sand
sandyclay
clay
siltyclay
silty clayloam
clayloam
loam siltyloam
silt
sandy clayloam
sandyloam
loamy sandsand
Gravel 2-64 mm
Sand 0.05-2 mm
Silt 0.002-0.05 mm
Clay less than 0.002 mm
Soil Texture Triangle
Properties of Soils with Different TexturesProperties of Soils with Different Textures
TextureNutrient InfiltrationWater-HoldingAeration TilthCapacity Capacity
Clay Good Poor Good Poor Poor
Silt Medium Medium Medium Medium Medium
Sand Poor Good Poor Good Good
Loam Medium Medium Medium Medium Medium
Refer to Fig. 10-15 p. 215Refer to Fig. 10-15 p. 215
Why care about soil texture?predicts fertility and use
Why care about soil texture?predicts fertility and use
Chemical Properties of SoilChemical Properties of Soil
• pH• Fertility
– 20 minerals needed for plant growth– Major Nutrients (N-P-K)
• Nitrogen• Phosphorus• Potassium
– Minor Nutrients• Soil Tests
Soil ErosionSoil Erosion
The movement of soil components from one The movement of soil components from one place to another by wind and water.place to another by wind and water.
• Sheet erosionSheet erosion – water moves down a slope or – water moves down a slope or across a field in a wide flowacross a field in a wide flow
• Rill erosionRill erosion – surface water forms fast-flowing – surface water forms fast-flowing rivulets that cut channels in the soilrivulets that cut channels in the soil
• Gully erosionGully erosion – rivulets join together and cut – rivulets join together and cut channels wider and deeper until they become channels wider and deeper until they become ditches and gullies.ditches and gullies.
Areas of serious concern
Areas of some concern
Stable or nonvegetative areas
Global Soil ErosionGlobal Soil Erosion• loss of soil organic matterloss of soil organic matter
• reduced ability to store reduced ability to store waterwater
• increased use of fertilizerincreased use of fertilizer
• floodingflooding
• sedimentationsedimentation
DesertificationDesertification
CausesCauses• OvergrazingOvergrazing• DeforestationDeforestation• Surface miningSurface mining• ErosionErosion• SalinizationSalinization• Soil compactionSoil compaction
ConsequencesConsequences• Worsening droughtWorsening drought• FamineFamine• Economic lossesEconomic losses• Lower living Lower living
standardsstandards• Environmental Environmental
refugeesrefugees
Conversion of rangeland, rain-fed cropland, or irrigated cropland to desert-like land, with a drop in agricultural productivity of 10% or more.
Soil DegradationSoil Degradation
Salinization -the accumulation of salt
Salinization -the accumulation of salt
Waterlogging –saturation of soil with irrigation water or excess precipitation so the water table rises close to the surface.
Waterlogging –saturation of soil with irrigation water or excess precipitation so the water table rises close to the surface.
EvaporationTranspiration
Evaporation
Waterlogging
Less permeableclay layer
Solutions: Soil ConservationSolutions: Soil ConservationConventional-tillageConventional-tillage
Conservation tillage Conservation tillage
Cropping methods Cropping methods
WindbreaksWindbreaks
Conventional tillageConventional tillage
• Crop cultivation Crop cultivation method in which method in which a planting surface a planting surface is made by is made by plowingplowing land, land, breaking upbreaking up the the exposed soil, and exposed soil, and then then smoothingsmoothing the surface.the surface.
Conservation tillageConservation tillage
• Crop cultivation in Crop cultivation in which soil is which soil is disturbed littledisturbed little ((mini-mum tillage mini-mum tillage farmingfarming) or ) or not at not at allall ( (no-till farmingno-till farming) ) to reduce soil to reduce soil erosion, lower erosion, lower labor costs, and labor costs, and save energy.save energy.
TerracingTerracing
Contour planting and strip croppingContour planting and strip cropping
Alley croppingAlley cropping
WindbreaksWindbreaks
Soil RestorationSoil Restoration
Crop RotationCrop Rotation– planting a field with different planting a field with different
crops from year to year to reduce crops from year to year to reduce soil nutrient depletion.soil nutrient depletion.
Soil RestorationSoil Restoration
Organic FertilizersOrganic Fertilizers• Animal manure
– Improves soil structure– Adds organic nitrogen– Stimulates beneficial soil bacteria and fungi
• Green manure– Fresh and growing green vegetation
• Compost– Microorganisms break down organic matter
in the presence of oxygen
Soil RestorationSoil RestorationCommercial Inorganic FertilizersCommercial Inorganic Fertilizers
Nitrogen, Phosphorus and PotassiumNitrogen, Phosphorus and Potassium– N, P, KN, P, K
• AdvantagesAdvantages– Easily transported, stored, and appliedEasily transported, stored, and applied
• DisadvantagesDisadvantages– Not adding humusNot adding humus– Reducing organic matter contentReducing organic matter content– Lowering oxygen contentLowering oxygen content– Supply only 2 or 3 of the more than 20 Supply only 2 or 3 of the more than 20
nutrients needednutrients needed– Require large amountsRequire large amounts– Release nitrous oxidesRelease nitrous oxides