The Lithosphere and the Hydrosphere

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The Lithosphere and the Hydrosphere

• Observatory Chapter 6 pages 182-219

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Why study the lithosphere and hydrosphere?

• The earths crust, freshwaters and oceans have
  given humans the means to survive and prosper.
• Thanks to the resources provided by the
  lithosphere and hydrosphere, we have built
  cities, farmed landscapes, developed
  technologies, fuelled engines and acquired our
  food.

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The Lithosphere

• Observatory textbook pages 183-200

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1. The Lithosphere

• The lithosphere is the hard shell of the Earth,
  consisting of the crust and the topmost part of
  the upper mantle.
• It is an average of 100km thick.
• It contains the minerals, rocks and soils that
  humans have used for building materials, metals
  and agriculture.

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1.1 Minerals

• Minerals are solid inorganic substances with
  clearly defined composition and properties.
• In most minerals atoms are organized in the form
  of identically shaped crystals.
• Each mineral has its own distinct chemical
  composition.
• 4000 different minerals exist on Earth.

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Examples of Minerals

• Gold (Au)
• Copper (Cu)
• Iron (Fe)

• Quartz (SiO2)
• Copper sulfate (CuSO4)

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Gold Ore
Quartz
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Classifying Minerals

• Minerals are classified according to the
  following 4 properties
• Colour
• Transparency
• Hardness
• Streak

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1. Colour

• Idiochromatic minerals have a characteristic
  colour.
• eg azurite is blue
• Allochromatic minerals vary in colour.
• eg quartz

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2. Transparency

• Minerals are one of the following
• Transparent (let light pass through)
• Translucent (let light through but blurred)
• Opaque (no light passes through)

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3. Hardness

• Minerals are classified according to how hard
  they are.
• Mohs scale assigns a value from 1 to 10 to
  indicate a minerals hardness.
• Talc is soft and scores a 1 on Mohs scale
• Quartz scores a 7
• Diamond scores a 10

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4. Streak

• When a mineral is rubbed on a surface it leaves a
  powder streak that is a characteristic colour for
  that mineral.

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Mining of Minerals
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Mining of Minerals

• Minerals are extracted from rock ores which are
  mined from the lithosphere.
• Quebec is known for large deposits of gold,
  copper, zinc, and most recently diamonds.
• Once the ore is extracted, the mineral is
  separated from the rock by chemical and physical
  means.

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1.2 Rocks

• Rocks are heterogenous solids composed of many
  minerals.
• The physical and chemical properties of rocks are
  not strictly defined.
• There are 3 types of rocks
• Igneous
• Sedimentary
• Metamorphic

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1. Igneous Rocks

• Formed when magma (molten rock) cools and
  solidifies
• eg granite

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2. Sedimentary Rocks

• Formed by the accumulation and compaction of
  debris at the bottom of lakes and oceans.

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Limestone is a sedimentary rock used in
construction
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3. Metamorphic Rocks

• Former igneous or sedimentary rocks that have
  been transformed by heat or pressure underground.
• eg granite turns to gneiss
• eg limestone turns to marble

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1.3 Soils

• As rock erodes due to rain, frost and wind, the
  fragments of rock mix with decomposing plants and
  animals.
• Eventually, soil is produced.
• It takes 200 years to form 1cm of soil!

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Soil Horizons

• As soils thicken they form distinct layers called
  horizons.

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Importance of Soils

• Soils absorb, filter and store water.
• Create a habitat for micro-organisms that
  decompose organic matter.
• Create a habitat for a variety of insects and a
  nutrient source for plants.
• Resist changes in pH through their buffering
  capacity. Soils can neutralize acids or bases.

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Environmental Damage to Soils

• The use of heavy machinery compacts the soil
  which reduces the oxygen content and prevents
  rain from penetrating the rainwater runoff
  carries away the nutrients needed for plant
  growth.
• Accelerated crop rotation prevents soils from
  regenerating nutrients naturally as a result
  more fertilizers have to be used.
• Excessive use of pesticides contaminate the soil
  and can reduce biodiversity by killing many
  beneficial microorganisms and insects.

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1.4 Permafrost

• Soils that are permanently frozen
• 50 of Canada is covered in permafrost
• Can be up to 500m thick
• Found at high latitudes and altitudes
• Makes construction difficult
• If the permafrost melts, the ground becomes
  unstable.

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Permafrost
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1.5 Energy Resources from the Lithosphere

• Fossil Fuels
• Uranium
• Geothermal Energy

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Fossil Fuels

• Coal, oil, natural gas
• 60 of the worlds energy supply
• formed from the remains of dead plants and
  animals (p. 196)
• When organisms died they sank to the bottom of
  lakes and oceans and were covered with layers of
  sediment
• Over millions of years they slowly turned to
  fossil fuels

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Problems with Fossil Fuels

• When fossil fuels burn they release thermal
  energy (heat) which can be converted into
  mechanical or electrical energy (eg car engine,
  home heating).
• Fossil fuels will eventually run out within the
  next few decades.
• Furthermore, burning fossil fuels produces gases
  which are damaging to the environment.

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Gases released when burning fossil fuels

• CO2 and CO ? major greenhouse gases
• SO2 and NOx ? creates acid rain
• NOx ? produces smog
• Note that the fossil fuel natural gas or methane
  (CH4) is itself a greenhouse gas 21 times more
  powerful than CO2

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Uranium

• Uranium is a radioactive element found in the
  lithosphere.
• When the nuclei of uranium atoms split a huge
  amount of energy is released (nuclear fission).
• This nuclear energy can be harnessed and
  converted into electrical energy inside a nuclear
  power plant.

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Advantages of Nuclear Energy

• lt 1 kg of uranium can produce as much electrical
  energy as 70 000 kg of coal.
• Fission of the uranium atoms does not release
  greenhouse gases.

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Disadvantages of Nuclear Energy

• The energy emitted from fission is accompanied by
  radioactivity.
• Risk of an accident a constant concern.
• Waste is produced which remains radioactive for
  hundreds of years.
• There is no method to neutralize radioactivity
  so the waste is stored underwater in large pools
  or buried in old mines.

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Geothermal Energy

• Molten rock beneath the lithosphere contains a
  huge amount of heat energy.
• To harness this geothermal energy a fluid is
  circulated deep underground which heats up and
  rises to the surface with a higher temperature.
• This warm fluid can be used to heat buildings
  (eg Carleton University).
• Geothermal energy is renewable and non-polluting
  (no greenhouse gas emissions).
• A few geothermal systems for heating buildings
  are now in use but they remain expensive to
  construct.

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Lithosphere Review

• Answer questions 1 to 19 on pages 214-215
• Use your notes and refer to pages 183 to 200 in
  Observatory to guide you in your responses

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