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 earth’s 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.ST
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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.ST
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Examples of Minerals• Gold (Au)• Copper (Cu)• Iron (Fe)
• Quartz (SiO2)• Copper sulfate
(CuSO4)
Gold Ore Quartz
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Classifying Minerals
Minerals are classified according to the following 4 properties:
1. Colour2. Transparency3. Hardness4. 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 mineral’s 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.ST
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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:
1. Igneous2. Sedimentary3. 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.
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!ST
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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.ST
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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 world’s 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.ST
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Advantages of Nuclear Energy
• < 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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