Overview of Environmental Geology
Steve Dutch Lab Sciences 402 Phone: 465-2246
e-mail: dutchs@uwgb.edu
HOME PAGE: http://www.uwgb.edu/dutchs
University of Wisconsin-Green Bay
Exponential Growth
- Doubling time = 72 years / % annual growth rate
- 4% = 18 years
- 3% = 24 years
- 2% = 36 years
- 1% = 72 years
- Implications for Earth
- You can't get an infinite amount of anything (like people) into a
finite space
- You can't get an infinite amount of anything (like resources) out of a finite space
- Nothing can grow forever
- At 2% per year, global population will be:
- 12 billion in 2041
- 24 billion in 2077
- 48 billion in 2113
- One person per square meter (land and sea) in 2594
- Equal to the mass of the earth in 3596
- What will limit growth?
- Natural methods (famine, disease and war)
- Imposed by society (China's one-child policy)
- Personal preference
- No amount of environmental awareness will matter unless population
growth stops
- Population Equals Regulation.
- We will have the low level of regulation we had in the 19th century
when we have the population density we had in the 19th century.
- There is no refuge in sparsely populated areas. Taxation and
regulation are dictated by urban population centers. Population pressure
causes in-migration to sparsely populated areas.
- Even with low population, we will not return to complete lack of
regulation. In many ways 300 million of us are managing the environment
better than 50 million of us did in the 19th century.
- Impacts on Earth
- Diversion of primary capacity to feed humans (now at least 25%)
- Destruction and fragmentation of habitat
- Direct consumption of animals and plants for food and fuel
- Increased degradation of land by erosion
- Increased hazard to humans as populations in dangerous terrain
increase
- Prognosis
- Humans will probably always operate in crisis management mode (not
dealing with a problem always offers immediate returns)
- Sooner or later we will miscalculate our ability to avert disaster
- Could the U.S. become a Third World Country?
- China on track to become world's largest industrial society
- India rapidly becoming largest producer of technical specialists in
the world
- Insufficient reward system to supply U.S. demand for scientists and
engineers
- Economic and legal disincentives for innovation in U.S.
- In many Third World countries, the top positions are unproductive
bureaucratic posts
North America: the Disney Continent
- No other continent is as benign for human habitation as temperate North
America
- Few dangerous predators
- Few highly poisonous organisms
- Few serious native diseases
- It's not like that in the rest of the world
- Europe is largely an artificial environment
- Fairy tales have a basis in historical reality. Europe was not
always so benign
- Until recently, predators were a significant hazard in much of the
world.
- Most water is non-potable
- Much surface water contains dangerous human parasites
- Highly venomous organisms
- Lethal diseases common
Minerals
- Toxins
- Carcinogens
- Radiological hazards
- Uranium
- Thorium
- Radium
- Radon
- Polonium
- Hazards arise from:
- Bulk Chemistry
- Trace impurities
- Physical State
Igneous Rocks and Volcanoes
- Direct volcanic hazards
- Lava Flows
- Rare as direct hazard
- Can cause fatal fires
- Ash falls
- Building Collapse
- Pollution of potable water
- Wear on livestock teeth
- Crop loss - probably main cause of loss of life in pre-modern
times
- High technology and ash do not mix!
- Pyroclastic flows
- Mudflows
- Landslides and cone collapse
- Floods
- Failure of dammed lakes
- Filling of stream channels
- Displacement of water
- Gases
- Climatic effects
- Stratospheric ash
- Sulfur aerosols
- Super-Volcanoes
- Magma chamber collapse
- Toba, Indonesia
- Long Valley, California
- Yellowstone
- Flood basalts
- Laki, Iceland, 1783
- Columbia Plateau, Washington
- Siberian traps
Surface Water
- Lack of potable water is the single greatest hazard to human health
- Women in arid developing regions spend up to 1/3 of their time
gathering water
- Diarrhea from contaminated water is the single greatest cause of
infant mortality.
- Aid workers have to fight to convince mothers that diarrhea is not a
normal childhood disease
- Problems with surface water
- Disease organisms
- Contamination by pollutants and sewage
- Overuse of Surface Water
- Western saying: "Whiskey's for drinking, water's for fighting over."
- Owens Valley, California
- Aral Sea
Ground Water
- Mechanics of ground water
- Recharge zone
- Aquifers
- Aquitards
- Springs, wetlands and lakes
- Artesian systems
- Wells
- Human impacts on ground water
- Cone of depression
- Migration of salt water and contaminants
- Contamination of aquifers
- Land subsidence
- Impact on surface water
Soils
- No soil, no food. It's that simple.
- Soils are complex entities, resulting from the interaction of:
- Time
- Climate
- Vegetation
- Drainage
- Types of Soils
- Little subsoil because of young age or slow weathering
- Entisols: barely beginning to form
- Inceptisols: a few centuries old
- Aridisols: limited development due to aridity
- Mature soils of temperate regions
- Spodosols: conifer forest soils
- Alfisols: deciduous forest soils
- Mollisols: silt and loess soils, prairie soils
- Mature soils of warm regions
- Ultisols: very old subtropical soils
- Oxisols (laterites): very old tropical soils
- Nutrient poor because most soluble materials leached away
- Soils dominated by special materials
- Andisols: volcanic ash soils
- Histosols: peat soils
- Gelisols: soils on permafrost
- Vertisols: soils churned by expansion and shrinkage of clays
- Soil Erosion
- Poor plowing practices
- Overgrazing
- Deforestation
- Other Soil Degradation
- Climatically inappropriate farming
- Urbanization
- Soil preservation approaches
- Contour plowing
- Strip cropping
- No-till agriculture
- Reforestation
Mass Wasting
Movement of material downhill by gravity
- Fast or slow?
- Wet or dry?
- Cohesive or fragmented?
| |
Slow Movements |
Rapid Movements |
| Cohesive |
Fragmented |
Cohesive |
Fragmented |
| Wet |
Creep |
Slump |
Mudflow |
| Dry |
Avalanche, Rockfall |
Water contributes enormously to mass wasting
Glaciers
and the Cryosphere
- Glaciers per se are little hazard
- Can deform structures on or in ice (U.S. South Pole station)
- Can advance and require relocation of structures and settlements
(Little Ice Age)
- Glacial floods (Jokulhlaups)
- Failure of ice-dammed lakes
- Hidden and subglacial lake floods (French Alps, 1898)
- Subglacial volcanism (Iceland)
- Frozen ground
- Melting of permafrost
- Solifluction
- Cryoseisms
- Glaciers and Sea Level
- Natural change since Pleistocene
- Global warming
- Mountain glaciers are disappearing worldwide
- Ablation of ice caps can result in meters of sea level rise
- Possible instability of West Antarctic ice cap
- Total meltdown of ice caps unlikely
Deserts and Wind Erosion
- Desertification
- Expansion of deserts at the margins due to overgrazing and
deforestation
- "The Bedouin is not the son of the desert, but its father."
- North Africa was forested in pre-Roman times
- Sub-Saharan Africa
- Wind Erosion
- Loess soils feed the world
- Present-day wind erosion strips topsoil
- Burial of vegetation or exposure of roots
- Respiratory hazards
- Cost of clearing wind-blown sediment from roads
Coastal Processes
- Storm Surges
- Galveston, 1900
- Bangladesh, 1971
- New Orleans, 2005
- Subsidence
- Louisiana
- Pozzuoli, Italy
- Erosion
- Effects on property values
- Attempts to control
- Eustasy: changes in global sea level
Earthquakes and Earth's Interior
- What Causes Earthquakes?
- Most Quakes Occur along Faults (Fractures in Earth's
Crust)
- Volcanic earthquakes due to magma movement and caldera collapse
- Elastic Rebound Theory
- Epicenter and Focus
- Types of Faults
- Joints - No Movement
- Strike-Slip
- Dip-Slip
- Major Hazards of Earthquakes
- Building Collapse ("Earthquakes don't kill people, buildings kill
people")
- Landslides
- Fire
- Tsunamis (Not Tidal Waves!)
- Safest & Most Dangerous Buildings
- Small, Wood-frame House - Safest
- Steel-Frame
- Reinforced Concrete
- Unreinforced Masonry
- Adobe - Most Dangerous
- Tsunamis
- Caused Probably by Submarine Landslides
- Travel about 400 M.p.h.
- Pass Unnoticed at Sea Cause Damage on Shore
- Warning Network Around Pacific Can Forecast Arrival
- 2004 Indonesian tsunami may lead to global system
- Whether or Not Damage Occurs Depends on
- Direction of Travel
- Harbor Shape
- Bottom
- Tide & Weather
- Seismology
- Seismic Waves
- P-Waves
- S-Waves
- Surface Waves
- Magnitude and Intensity
- Intensity: How Strong Earthquake Feels to Observer
- Depends On:
- Distance to Quake
- Geology
- Type of Building
- Observer!
- Varies from Place to Place
- Mercalli Scale- 1 to 12
- Magnitude - Determined from Seismic Records
- Richter Scale:
- Related to Energy Release
- Exponential
- Seismic - Moment Magnitude
- Modifies Richter Scale, doesn't replace it
- Adds about 1 Mag. To 8+ Quakes
- Strategies of Earthquake Prediction
- Lengthen Historical Data Base
- Historical Records
- Paleoseismology
- Short-term Prediction
- Long-term Prediction
- Modeling
- Dilatancy - Diffusion: cracks open and fluids weaken
the rock, hastening its failure.
- Stick - Slip: studies of how and why materials
slip.
- Asperities: sticking points on faults, typically bends.
- Crack Propagation: studies of how cracks form,
expand, and join.
- Are Earthquakes Getting More Frequent?
- No
- Casualties increasing
- Population growth
- Pressure to move into unsafe areas
- Deforestation and overgrazing increase chances for landslides
Resources
- Reserves and Resources
- Mineral Resources
- Metallic versus non-metallic
- Extraction methods
- Underground
- Open Pit
- Placer
- Environmental Impacts
- Hazard to miners
- Dust
- Noise
- Waste piles
- Acid runoff and leaching
- Boom and bust cycles
- Non-Petroleum energy resources
- Coal
- Mining methods
- Underground
- Longwall
- Strip
- Open-Pit
- Environmental Impacts
- Hazard to miners
- Waste piles
- Acid runoff and leaching
- Sulfur emissions
- Heavy metals in fly ash
- Uranium
- Mining methods
- No different from any other metal
- Underground
- Open-Pit
- Environmental Impacts
- Radiation hazards in mining
- Storage of nuclear waste
- Radium leaching from tailings
- Geothermal
- Low thermodynamic efficiency
- Non-productive gases
- Mineralized brines
- Corrosion and mineralization of plant
- Depletion of hot aquifer
- Petroleum and Natural Gas
- Geopolitical and Geological realities
- Most oil is in a small number of very large pools
- These are called "Giant" and "Supergiant" because they are
big
- We are running out of places to hide them
- Discovery rate of large fields has been falling for half a
century
- We are using oil three times faster than we are discovering
it
- Half of all oil is in the Middle East
- Can be related to plate tectonic setting
- Nothing else like the Middle East exists
- Most of the world (abyssal plains, Precambrian shields)
unlikely to have much oil
- Hubbert Curves
- M. King Hubbert used discovery statistics to project future
oil production in 1956
- The U.S. has followed his prediction almost exactly
- Global oil production is close to peak
- We will not run out of oil for at least a couple of
centuries
- Demand will exceed supply
- Users will bid price up
- China is emerging as world leader in manufacturing
- Very dirty technology, but hopefully will improve
- Moving to secure future energy sources
- Will compete with West for energy
- You can bet they are planning for the day when they have to
fight for energy
- Petroleum production
- Despite the term "oil pool," oil actually migrates upward until
trapped from above
- Oil contained in pose spaces of rocks and moves slowly
- Natural pressure essential for efficient recovery of oil
- Initially, pressure may be sufficient to force oil to
surface
- Oil only moves through the rocks just so fast
- Excessive drilling and extraction will bleed off pressure
and reduce the total recovery
- Levels of production
- Primary: oil flows naturally under pressure
- Secondary: water pumped into wells to mobilize oil
- Tertiary: steam or solvents used to mobilize oil
- Non-conventional energy sources
- Methane hydrates
- Tar sands
- Oil shales
- Pore spaces too small and oil bound to rock too tightly to drill
- Crush rock and heat to extract oil
- Expensive and energy-intensive
- Serious environmental problems
- Oil mining
- Shallow oil reservoirs with viscous or slow-moving oil
- Drill shafts below oil and pump oil out of shafts
- Used in a few oil fields
- Hot dry rock geothermal
- Requires extremely deep drilling to reach hot rocks
- Production will be limited by heat flow
- Enjoyed a vogue in 1970's but probably a remote prospect
- Deep Earth gas hypothesis
- Hypothesis: carbon deep in earth may be in the form of methane
- Trial drilling in Sweden failed to support theory
- Significant minority of Russian petroleum geologists think
petroleum is sometimes of inorganic origin
Extraterrestrial Hazards
- Can we predict impacts?
- Incomplete inventory of objects
- Initial observations don't permit completely accurate predictions
- Comets vent gases and change orbits
- The meaning of probability of impact
- The Torino Scale of Impact Hazard
- Named for the city in Italy, not a person
- Assesses both probability of event and potential effects of impact,
so not completely consistent.
- Low or no hazard
- 0 - No danger, or object too small to penetrate atmosphere
- 1 - Normal. No likelihood of impact
- Merits attention by astronomers
- 2 - Close pass but no cause for concern
- 3 - 1% chance of impact causing local damage
- 4 - 1% chance of impact causing regional damage
- Threatening
- 5 - Close pass by object capable of causing regional damage
- 6 - Close pass by object capable of causing global effects
- 7 - Very close pass by object capable of causing global effects
- Certain Impact
- 8 - Impact capable of causing local damage or tsunami
- 9 - Impact capable of causing regional damage or tsunami
- 10 - Impact with global effects
- Likely impact scenarios
- Atmospheric impact and air burst (Tunguska, 1908)
- Surface impact causing local damage
- Surface impact with 100 km damage radius
- Surface impact with 1000 km damage radius
- Surface impact with global effects
- What happens during impact
- Atmospheric entry
- Microscopic objects gradually decelerate
- Millimeter-sized objects vaporize, seen as meteors
- Meter-sized objects may fragment and survive passage
- House-sized objects hit with force
- Contact-compression phase
- Transient crater phase
- Rebound and collapse phase
- Environmental Impacts
- Radiant heat and flash burns
- Blast wave
- Seismic waves
- Tsunami
- Ejecta
- Stratospheric dust
- Liberated volatiles (carbon dioxide, sulfur, methane)
- Impact volcanism - a myth
Military Impacts on the Environment
- Clausewitz: "War is policy carried on by other means."
- All war is inherently political
- The last general who was utterly unconstrained was Napoleon
- Incidental (collateral) damage
- Vehicle usage
- Cratering
- Vandalism (the Sphinx's nose)
- Modifications to facilitate own operations
- Generally small-scale and local due to time and materiel constraints
- Canal cutting (U.S. Civil War)
- Road building (Burma Road, Alcan Highway)
- Defoliation (Vietnam)
- Modifications to impede enemy
- Most common large-scale efforts. It's always easier to impede than
facilitate
- Fortifications and trenches
- Diversion of waterways
- Grant's Ditch at Vicksburg: bypass Vicksburg and destroy its
strategic significance
- Mongol diversions in support of siege
- Chinese diversions of Huang He
- Dam bombing (Ruhr Valley, Germany, World War II)
- Destruction of food supplies
- Scorched earth (Shenandoah Valley and Sherman's March, U.S.
Civil War)
- Destruction of buffalo to break Plains Indian culture
- Strategic Modifications
- Includes probably the largest scale engineering
- Shreve and opening of Red River
- Panama Canal
- Interstate Highway System
- Environmental Terrorism
- Kuwait, 1991
- Modern threat since concern for environment only recently emerged as
political force
- Doomsday weapons
- Nuclear Winter
- Soot and dust from large number of nuclear explosions would blanket the
stratosphere
- Lack of mixing in the stratosphere would inhibit dispersal
- Heating of aerosols at altitude and cooling of surface by obstruction of
sunlight would create persistent inversion, further inhibiting dispersal
- Blocking of sunlight would cool earth significantly
- Oil smoke from Gulf War was dramatic at ground level but did not reach
stratosphere or attain regional coverage.
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Created 3 Feb 2006, Last Update
15 January 2020