1 Principles of Environmental Science Inquiry and Applications Third Edition Cunningham Chapter 11 Lecture Outlines* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Environmental Geology and Earth Resources Chapter 11

3 Outline: Tectonic Processes Minerals and Rocks Economic Geology and Mineralogy  Strategic Resources Environmental Effects of Resource Extraction  Mining - Restoration Conserving Geologic Resources Geologic Hazards

4 A DYNAMIC PLANET A Layered Sphere  Core - Interior composed of dense, intensely hot metal. Generates magnetic field enveloping the earth.  Mantle - Hot, pliable layer surrounding the core. Less dense than core.  Crust - Cool, lightweight, brittle outermost layer. Floats on top of mantle.

5 A Layered Sphere

6 Tectonic Processes

7 Upper layer of mantle contains convection currents that break overlaying crust into a mosaic of tectonic plates.  Slide slowly across earth’s surface. - Ocean basins form where continents crack and pull apart. - Magma forced up through cracks in oceanic crust form mid-oceanic ridges.

8 Tectonic Processes

9 Tectonic Processes Cont’d Earthquakes are caused by grinding and jerking as plates slide past each other.  Mountain ranges pushed up at the margins of colliding plates. - When an oceanic plate collides with a continental landmass, the continental plate will ride up over the seafloor and the oceanic plate will subduct down into the mantle.  Deep ocean trenches mark subduction zones.

10 Pangea Geologists suggest that several times in earth’s history most, or all, of the continents gathered to form a single super-continent, Pangea, surrounded by a single global ocean.

11 MINERALS AND ROCKS A mineral is a naturally occurring, inorganic, solid element or compound with a definite chemical composition and regular internal crystal structure. A rock is a solid, cohesive, aggregate of one or more minerals.  Each rock has a characteristic mixture of minerals, grain sizes, and ways in which the grains are held together.

12 Rock Types Rock Cycle - Cycle of creation, destruction, and metamorphosis.  Three major rock classifications: - Igneous - Sedimentary - Metamorphic

13 Igneous Rocks Most common type of rock in earth’s crust.  Solidified from magma extruded onto the surface from volcanic vents. - Quick cooling of magma produces fine- grained rocks.  Basalt - Slow cooling of magma produces coarse-grained rocks.  Granite

14 GRANITE

15 Sedimentary Rock Deposited materials that remain in place long enough, or are covered with enough material for compaction, may again become rock.  Formed from crystals that precipitate out of, or grow from, a solution. - Shale - Sandstone - Tuff

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17 Metamorphic Rock Pre-existing rocks modified by heat, pressure, and chemical agents.  Chemical reactions can alter both the composition and structure of rocks as they are metamorphosed. - Marble (from limestone) - Quartzite (from sandstone) - Slate (from mudstone and shale)

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19 Weathering Mechanical - Physical breakup of rocks into smaller particles without a change in chemical composition. Chemical - Selective removal or alteration of specific components that leads to weakening and disintegration of rock.  Oxidation Sedimentation - Deposition of loosened material.

20 ECONOMIC GEOLOGY AND MINERALOGY Metals  Metals consumed in greatest quantity by world industry (metric tons annually): - Iron (740 million) - Aluminum(40 million) - Manganese(22.4 million) - Copper and Chromium(8 million ea) - Nickel(0.7 million)

21 Non-Metal Mineral Resources Sand and Gravel  Brick and concrete construction, paving, sandblasting and glass production. Limestone  Concrete and building stone Evaporites  Gypsum and Potash Sulfur  Sulfuric Acid

22 Strategic Metals and Minerals Durable, highly valuable, and easily portable, gemstones and precious metals have been a way to store and transport wealth.  These valuable materials have bankrolled despots, criminal gangs, and terrorism in many countries.  Much of the illegal trade ends up in the $100 billion per year global jewelry trade, two-thirds of which sells in the U.S.

23 Strategic Metals and Minerals

24 ENVIRONMENTAL EFFECTS OF RESOURCE EXTRACTION Mining  Placer Mining - Hydraulically washing out metals deposited in streambed gravel. - Destroys streambeds and fills water with suspended solids.  Strip-Mining or Open-Pit Mining - Large scars on land surface. - Tailings  Toxic runoff

25 Mining Underground Mining  Very Dangerous - Gas - Inhaling Particulate Matter - Tunnel Collapse

26 Restoration Surface Mining Control and Reclamation Act (1977) requires better restoration of strip- mined lands, especially if land classed as prime farmland.  Difficult and expensive. - Often more than $10, per hectare.  50% of U.S. coal is strip-mined.

27 Processing Metals are extracted from ores by heating or treatment with chemical solvents.  Smelting - Roasting ore to release metals. - Major source of air pollution.  Heap-Leach Extraction - Crushed ore piled in large heaps and sprayed with a dilute alkaline cyanide solution which percolates through the pile to dissolve the gold. - Effluent left behind in ponds.

28 CONSERVING GEOLOGIC RESOURCES Recycling  Aluminum must be extracted from bauxite by electrolysis. - Recycling waste aluminum consumes one-twentieth the energy of extraction from raw ore.  Nearly two-thirds of all aluminum beverage cans in U.S. are recycled.  Other metals commonly recycled: - Platinum, gold, copper, lead, iron, steel.

29 Substituting New Materials For Old Reduce metal consumption by using new materials or new technologies.  Plastic pipes in place of metal pipes.  Fiber-optics in place of metal wires.  Metal alloys in place of traditional steel.

30 GEOLOGIC HAZARDS Earthquakes - Sudden movements of the earth’s crust that occur along faults where one rock mass slides past another.  Gradual movement - creep. - When friction prevents creep, stress builds up until eventually released with a sudden jerk.  Frequently occur along subduction zones.  Tsunami - Seismic sea swells.

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37 Country where deaths occurred Deaths InjuredMissingDisplaced ConfirmedEstimated 1 Indonesia130,736167,736—37,063500,000+ Sri Lanka Sri Lanka 2 35,322 21,411516,150 India12,40518,045—5,640647,599 Thailand5,395 5, ,2128,4572,8177,000 Somalia78289——5,000 Myanmar (Burma) ,200 Maldives82108—2615,000+ Malaysia6868– — Tanzania1013——— Seychelles3357—200 Bangladesh22——— South Africa2424 2——— Yemen22——— Kenya112—— Madagascar————1,000+ Total ~184,168~230,210~125,00 0 ~45,75 2 ~1.69 million edit

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39 Volcanoes Volcanoes and undersea magma vents are the sources of most of the earth’s crust.  Many of world’s fertile soils are weathered volcanic material. - Human / Environmental Dangers  Volcanic Ash  Mudslides  Sulfur Emissions

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43 Volcanic ash from Pinatubo Volcano in the Philippines partly buries this village. The great 1991 eruption of Pinatubo was the second largest in the world during the 20th Century.

44 Floods Excess water that overflows stream banks and covers adjacent land.  Biggest economic loss is usually contamination, not direct property losses. - Carpet, furniture, drywall, etc.  Many human activities increase both severity and frequency of floods. - Soil compaction

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46 Floods Cont’d Floodplains often help mitigate flooding.  Usually flat, fertile, and easily farmed. - Flood control structures have separated floodplains from rivers. Flood Control  Governmental air of flooding victims seems to have encouraged building on floodplains.

47 Erosion Landslides  A general term for rapid down-slope movement of soil or rock. - Many human activities such as forest clearing and building homes on steep, unstable slopes increase both frequency and damage done by landslides.

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49 Erosion Cont’d Barrier Islands  Stand between mainland and open sea.  Contain many of world’s sandy beaches. - Many people place a high value on the view and beach access, and thus these are highly prized areas to build structures.  Assume modern technology will provide protection.