Earth

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Earth

• Earth formed from a solar nebula 4.6 Ga
• Life on Earth began 3.5 Ga
• Geology Science of processes related to
• Composition, structure, history and life of Earth
• Environmental Geology
• Studies entire spectrum of human interactions
  with the physical environment
• It is geology applied to
• Solve conflicts in land use
• Minimize environmental degradation
• Maximize the benefits of natural resources

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Animation

• Nebular Hypothesis
• Solar System

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Animation

• Relative Dating 2D
• Dating 3D

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Earth is Unique

• No other planet in the solar system currently has
  the right chemical and physical mix needed to
  support life
• No conclusive evidence of life existing elsewhere
  in the universe has yet been discovered as far as
  we know

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What Do Geologists Do?

• Seek to understand all processes that operate on
  and inside the Earth
• Study
• Our planets long history
• Water bodies (rivers and lakes)
• Hazardous processes such as earthquakes, volcanic
  eruptions, flood, and landslides
• Rocks/minerals

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Env. Geology Involves Study of

• Earth Materials (rocks, minerals, soils)
• formation, effects on health, as resource or
  waste
• Natural Hazards
• floods, landslides, quakes, volcanic eruptions
• minimize loss of life
• Land for Site Selection
• Land use planning, environmental Impact analysis
• Hydrologic Processes of surface/ground water
• Water resources, pollution
• Global Geologic Process
• Atmospheric, hydrologic, and lithospheric

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Exponential Growth Rate

• The population growth is defined by
• Pt Po ert
• Pt is the population at a given time t
• Po is the original population
• r is the growth rate (per time t-1 or 1/t)
• t is time (t)
• e is the base of the natural log (i.e., ln)
  function (e12.718)
• Unit of P is (i.e., number of) of people
  because
• ( of people) ( of people) e (1/t)(t)
• The rate (i.e., slope) of growth (i.e.,
  people/time) of the population increases with
  time
• In simple math the eqn. for exponential growth
  is
• Pt/Po100.3n where nnumber of doubling time

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Example Start with 0 persons. Assume that after
a year, each person has two babies. What is the
rate of growth?

• Year (t) 0 1 2 3 4
• Population (Pt) 0 2 4 8 16
• Rate of growth 0 1 2 4 8
• Starting at an arbitrary time, the population is
• 2 times (i.e., 21) as large after each doubling
  time tDo
• 4 times (i.e., 22) as large after 2 doubling
  times, 2tD
• 8 times (i.e., 23) as large after 3 tD In
  general Pt Po 2n
• Population Number of doubling times (tD)
  passed
• 1 20 Po 0 ?
  
• 2 21 Pt 1 ?
  ?
• 4 22 Pt 2 ? ?
  ? ?
• 8 23 Pt 3 ? ? ? ?
  ? ? ? ?
• 2n Pt n or in general PtPo2n100.3n
• Exponential growth occurs by an excess of births
  over death
• As the absolute number of people increases, the
  number of people added each year will increase
  also, yielding a concave upward curve

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Overpopulation

• Human Population Growth
• Rate of growth increased due to better
• agriculture, sanitation, medicine, energy sources
• Overpopulation
• Started few centuries ago
• Is a global problem
• See Figure 1.3 (next slide)
• Population Grows Exponentially

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An Example

• Excel Worksheet

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Example 1 - Simple Math

• If the ratio of U.S. population in year 2090
  (i.e., Pt) to that of 1850 (i.e., Po) is 16,
  find
• How many doubling times have passed (i.e., n)
• Duration of each doubling time
• per year increase of the population (i.e.,
  growth rate)
• Pt Po2n 100.3n
• Pt/Po 100.3n
• 16 100.3n Now take logarithm of both sides
• log16 0.3n log 10 (Note log10 1)
• log24 0.3n (Note logxn nlogx)
• 4log2 0.3 n
• n 1.2 /0.3 4
• 2090 - 1850 240
• 240/4 60 (duration of each doubling time in
  years) 
• tD 60 70/r
• growth rate 1.17 (i.e., per year increase)

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Example 2

• If the population of a country doubles its size
  each 40 years (i.e., tD 40), and if the
  population in 1980 is 10x10 6 heads (i.e., Po),
  calculate the
• population in the year 2100 (i.e., Pt)
• per year increase of the population (growth
  rate per year)
• Pt Po2n 100.3n
• Pt/Po 100.3n
• Time period 2100-1980 120 years
• n 120/40 3
• Pt Po2n Po 23 Po100.3(3)
• Pt Po100.9
• Pt 10x106 (100.9)
• log Pt log106log100.9log 10
• log Pt 160.9 7.9
• Pt 107.9 (population in the year 2100)
• tD 0.693/r ? 40 70/
• ? growth rate per year 1.75

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Growth of Worlds Population

• Worlds population was 300 M about 2 ka
• It apparently didn't increase much up to AD 1000
• It reached 800 million by the beginning of the
  Industrial Revolution in 1750
• Average growth rate0.13 in 750 yrs from
  10001750
• By 1800, population reached one billion while the
  second billion was reached by 1930 (i.e., in 130
  yrs)
• Average growth rate 0.53 p.a.
• From 1930 to 1960, population reached 3 billion
  (30 yrs)
• Average growth rate 1.36 p.a.
• By 1974, the fourth billion was reached (in 14
  yrs)
• Average growth rate 2.1 from 1960 to 1974
• From 1974 to 1990, the mark hit five billion (in
  16 yrs)
• Average growth rate slowed to 1.4

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Effect of Population on Earth Resources

• Degradation of the environment by pollution
• Pollution Unfavorable alteration of our
  surroundings, wholly or largely as a by-product
  of human action
• Serious shortages of resources (including food)
• Is brought by straining Earths ability to
  provide food, clothing, shelter, and energy
• e.g., on the average, each of us, on a yearly
  basis, uses
• 500 kg of steel, 25 kg of Al, 200 kg of salt

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Effect of Population on Earth Resources

• Development of Geologic Problems
• As homes replace fields in flat areas, farming is
  displaced to hilly regions
• Steeper slopes accelerate soil loss, polluting
  streams with sand silt
• An increased rate of injuries, property damage,
  and loss of life (due to geologic hazards)

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Humans are affecting the Earth system in many
ways

• Burning petroleum and coal, which increases the
  greenhouse effect
• Intensive farming activities, which have an
  impact on soil, ground and surface water
• Production and release of gases containing
  chlorine, which destroys ozone
• Redistribution of water through the construction
  of giant reservoirs, which changes the
  distribution of weight at Earths surface and
  alters, slightly but measurably, the rotation of
  the Earth on its axis

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Human Influences

• Our daily activities are having measurable
  effects on
• Rainfall
• Climate
• Air
• Water quality
• Erosion
• Mineral resources
• In North America, we use 20 tons of mineral
  resources per person/year

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Sustainability

• Is an environmental objective!
• Goal to ensure that future generations have equal
  access to Earth resources
• Is a long-term objective, achieved over decades
  or centuries
• Requires types of development that
• Are economically viable
• Do no harm the environment
• Are socially just

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Sustainability of Resources

• Possible for the renewable resources such as air,
  water, fish, forest, domesticated stock and
  wildlife, agricultural products
• For non-renewable resources, such as fossil fuels
  and minerals, sustainability is possible by
• Conservation/Recycling to extend their
  availability
• Finding substitution (alternative) for the
  material

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Global Environmental Problems

• Deforestation
• Soil erosion
• Water and air pollution
• Desertification
• Pollution due to mining (minerals, coal, oil)
• Overuse of groundwater and surface water
  resources (e.g., Aral Sea)

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System Concept

• A system is any portion of the universe that can
  be isolated from the rest of the universe for
  observing and measuring change
• The simplest kind to understand is an isolated
  system
• the boundary completely prevents the exchange of
  either matter or energy

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Open and Closed Systems

• The nearest thing to an isolated system in the
  real world is a closed system
• exchanges energy with its surroundings, but not
  matter
• An open system can exchange both energy and
  matter across its boundary

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Earth system

• Energy and materials (like water, carbon, and
  minerals) are transferred from one system to
  another
• To a close approximation, Earth is a closed system

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Earth system

• Earth is only approximately a closed system
  because
• Meteorites do come in from space and fall on
  Earth
• A tiny trickle of gases leaves the atmosphere and
  escapes into space
• Earth is comprised of four open systems

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Our Planets Four Spheres or Subsystems

• The atmosphere
• Nitrogen, oxygen, argon, carbon dioxide, and
  water vapor
• The hydrosphere
• Oceans, lakes, streams, underground water, snow,
  and ice
• The biosphere
• All of Earths organisms, as well as any organic
  matter not yet decomposed
• The geosphere
• The solid Earth from core to surface, composed
  principally of rock and regolith

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System Approach

• The whole Earth behaves like an organism
• It is a self-regulating network of interdependent
  physical and biological systems
• A disturbance (e.g., deforestation) in one part
  of the system (Earth) must result in adjustment
  in other parts (e.g., global warming)

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Environment influenced by three inter-related
variables

• 1.      Earth
• rocks and minerals
•    origin, variety, distribution, and pollution
  of soil
•    causes of, distribution, and prediction of
  earthquake/volcanic activity
•    cause and prevention of coastal erosion and
  slope failure
•    mineral and water resources

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Environment influenced by three inter-related
variables

• 2.      Air
• composition and circulation
• pollution by human activities
• climate

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Environment influenced by three inter-related
variables

• 3.      Water
• distribution
• movement and flooding
• range in chemical composition
• pollution by human activities
• management

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Inter-relationship of atmosphere, hydrosphere,
lithosphere

• H2O circulates freely among the
•          atmosphere (as gas, e.g., vapor)
•          ground surface (as solid, e.g., ice,
  and liquid water)
•          subsurface (liquid water)
•  
• Solid surface material are
•          carried to the ocean by runoff (as
  suspended, dissolved, and bed loads)
•          carried to the atmosphere by wind (as
  dust)

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Cyclical Movements

• The movement of materials is continuous
• There are two key aspects to cycles
• The reservoirs in which the materials reside
• The flows, or fluxes, of materials from reservoir
  to reservoir
• The speed of movement differs greatly in
  different cycles

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Three Most Important Cycles

• The hydrologic cycle
• Water in Earths hydrosphere
• The rock cycle
• Rock is formed, modified, decomposed, and
  reformed by the internal and external processes
  of Earth
• The tectonic cycle
• Movements of plates of lithosphere, and the
  internal processes of Earths deep interior that
  drive plate motions

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The hydrologic cycle

• Is powered by heat from the sun
• Encompasses the movement of water in the
  atmosphere, in the hydrosphere, on the Earths
  surface, and in the Earths crust

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Rock Cycle

• Rock is any naturally formed, nonliving, firm and
  coherent aggregate of mineral matter that
  constitutes part of a planet.
• The three rock families
• Igneous rock
• Created through the cooling and solidification of
  magma
• Sedimentary rock
• Formed from deposits of sediment
• Metamorphic rock
• Formed by the effects of pressure and heat on
  existing rocks

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Tectonic Cycle

• Tectonics is the study of the movement and
  deformation of the lithosphere
• When magma rises from deep in the mantle, it
  forms new oceanic crust at mid ocean ridges
• The lifetime of oceanic crust is shorter than the
  lifetime of continental crust
• The most ancient oceanic crust of the ocean
  basins is only about 180 million years old, and
  the average age of all oceanic crust is about 70
  million years old

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Tectonic Cycle

• When all oceanic crust sinks back into the
  mantle, it carries some water with it
• The water is driven off during volcanic eruptions
• Some constituents in the hot rock (calcium,
  magnesium) are the same as those of seawater

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Other cycles

• The other cycles include the biogeochemical
  cycles
• Carbon
• Oxygen
• Nitrogen

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