The Lithosphere and the Hydrosphere Observatory Chapter 6: pages 182-219 ST EST AST ES

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. ST EST AST ES

The Lithosphere Observatory textbook pages 183-200 ST EST AST ES

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 EST AST ES

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 EST AST

Examples of Minerals Gold (Au) Copper (Cu) Iron (Fe) Quartz (SiO2) Copper sulfate (CuSO4) ST EST AST Gold Ore Quartz

Classifying Minerals Minerals are classified according to the following 4 properties: Colour Transparency Hardness Streak ST EST AST

1. Colour Idiochromatic minerals have a characteristic colour. eg: azurite is blue Allochromatic minerals vary in colour. eg: quartz ST EST AST

2. Transparency Minerals are one of the following: Transparent (let light pass through) Translucent (let light through but blurred) Opaque (no light passes through) ST EST AST

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 ST EST AST

4. Streak When a mineral is rubbed on a surface it leaves a powder streak that is a characteristic colour for that mineral. ST EST AST

Mining of Minerals ST EST AST

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 EST AST

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 ST EST AST

1. Igneous Rocks Formed when magma (molten rock) cools and solidifies eg: granite ST EST AST

2. Sedimentary Rocks Formed by the accumulation and compaction of debris at the bottom of lakes and oceans. ST EST AST Limestone is a sedimentary rock used in construction

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 ST EST AST

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 EST ES

Soil Horizons As soils thicken they form distinct layers called horizons. ST EST ES

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 EST ES

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. ST EST ES

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. ST EST

Permafrost ST EST

1.5 Energy Resources from the Lithosphere Fossil Fuels Uranium Geothermal Energy ST EST AST

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 ST EST AST

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. ST EST AST

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 ST EST AST

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 EST AST

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. ST EST AST

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. ST EST AST

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. ST EST AST

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 ST EST AST ES