Chapter 14: Geology and Earth Resources

1. Chapter 14:Geology and Earth Resources By Karryn Christiansen and Missy Hutchings Dr. Unfried APES 7/8

2. “Onions have layers. Ogres have layers.”EARTH HAS LAYERS! The core is composed of a dense, intensely hot mass of metal. Solid in the center, more fluid than the outer core The mantle surrounds the molten outer core and is a hot, pliable layer of rock. The crust is the outermost layer of the earth and is a cool, lightweight, brittle layer. The crust is like the ‘skin’ on warm chocolate pudding!

3. Tectonic Plates! • Upper layer of the mantle has huge convection currents that break the overlying crust into a mosaic of huge blocks called Tectonic plates! • Where oceanic plates separate, magma forces up through cracks to form mid-ocean ridges • When oceanic plates collides with continental landmass, continental plate rides up over the seafloor, so the oceanic plate is subducted, or pushed down into the mantle • Deep oceanic trenches mark these subduction zones, and volcanoes form where the magma erupts through vents and fissures in the overlying crust • RING OF FIRE- where the oceanic plates are being subducted under the continental plates and is the source of more earthquakes and volcanic activity than any other place on Earth

4. In about 30 million years, Los Angeles will pass San Francisco! Earthquakes - Caused by the grinding and jerking as plates slide past each other or as they converge or diverge The continuous movement of plates is causing Southern California to slowly move north towards Alaska Plate movement varies greatly, from 1cm per year to as much as 18 cm per year at a seafloor spreading zones Over time continents have moved long distances- Antarctica and Australia were once connected to Africa

5. Minerals • A mineral is a naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure • Chemical composition and crystal structure categorizes minerals because no two minerals are alike in both of these respects These minerals are seen under a UV black light, showing their natural beauty

6. What did the rock and the ruler say to each other? “You rock!” “You rule!”

7. Rocks • 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 mixed and held together

8. The Rock Cycle • Cycle of creation, destruction, and metamorphosis the rock cycle • Understanding the cycle explains the origin and characteristics of different types of rocks, how they’re shaped, worn away, transported, deposited and altered • THREE TYPES!

9. Type 1: Igneous Rocks • Most common in the earth’s crust • Solidified from magma • Magma extruded from vents cools quickly to form basalt, rhyolite, andesite, and fine-grained rocks • Magma cools slowly forms granite, gabbro, and coarse-grained crystalline rocks

10. Weathering • Exposure to air, water, changing temperatures, and reactive chemical agents slowly breaks them down in process called weathering • Mechanical and chemical weathering • Oxidation- combination of oxygen with an element to form an oxide or hydroxide mineral • Hydrolysis- hydrogen atoms from water molecules combine with other chemicals to form acids

11. Sedimentation • Particles of rock transported by wind, water, ice and gravity • Deposition of new materials is sedimentation • Deposited material that remains in place long enough, or is covered with enough material to compact it, may become rock again or Sedimentary Rock

12. Type 2: Sedimentary Rock • Includes shale (compacted mud), sandstone (cemented sand), tuff (volcanic ash), and conglomerates (aggregates of gravel, sand, silt, and clay) • Formed from crystals that precipitate out of, or grow from a solution • Have distinct layers that show different conditions when they were laid down

13. Type 3: Metamorphic Rocks • When preexisting rocks are modified by heat, pressure, and chemical agents- forms metamorphic rock • Chemical reactions can alter both the composition and structure of rocks as they are metamorphosed • Examples: marble (from limestone), quartzite (from sandstone), and slate (from mudstone and shale)

14. Economic Geology and Mineralogy • Economic mineralogy- study of minerals that are valuable for manufacturing and important to domestic and international commerce • Most are metal-bearing ores • Very important to human affairs • US public policy has encouraged mining on public lands as a way of boosting the economy and utilizing natural resources

15. Metals in the Economy • Availability of metals have determined technological developments, and economic and political power for individuals and nations • Often formed in mountainous areas, where heat and pressure of mountain building concentrate ores • Mineral trade is crucially important to economic and social stability

16. Nonmetal Minerals • From silicate minerals to sand, gravel, salts, limestone, and soils. • Gemstones and precious metals are durable, highly valuable, and easily portable, making them a way to store and transport wealth • Much of the illegal trade ends up in the $100 billion/year global jewelry trade, two-thirds of which sells in the U.S.

17. What Happened? • 2004- a group of Nobel Peace Laureates called on the World Bank to overhaul its policies on lending for resource extractive industries • Extractive Industries Review appointed by World Bank recommended that areas of high biodiversity should be off-limits for extractive industries

18. What’s Being Mined? • Evaporitesare mined for halite, gypsum, and potash • Sulfur deposits are mined mainly for sulfuric acid production • In the U.S.- sulfuric acid use amounts to more than 200 lbs. per person every year

19. CASE STUDY! • December 26, 2004- huge undersea earthquake near Sumatra, Indonesia • Caused by a sudden lurch in the earth’s crust • Triggered a Tsunami (“harbor wave”) • Sumatra- 250,000 residents reported dead or missing. Millions left homeless • Nature also suffered- like coral reefs or the turtle nestlings

20. Environmental Effects of Resource Extraction • Metals from mines are used in our lights, computers, watches, fertilizers, and cars • Can have very severe and social consequences • Water quality is affected because toxic substances (ie cyanide) are required to chemically separate metals from the minerals that contain them • Huge amounts of ore must be crushed and washed, leaving water filled with sulfuric acid, arsenic and heavy metals, destroying aquatic ecosystems • Nevada uses 230,000 m3 (60 million gallons) of fresh water daily

21. Mining can have very serious environmental impacts • Many techniques for extracting geologic materials • Open-pit- extract massive beds of ores and other minerals, but groundwater accumulates at the bottom and a toxic soup results • Strip- land surface stripped away to expose the coal • Underground- dangerous, tunnels collapse, natural gas in mines can explode, water seeps in and is contaminated • Placer- pure nuggets are washed from stream sediment, chokes stream ecosystems with sediment • Mountaintop removal-long, sinuous ridge-tops are removed by giant shovels to expose horizontal beds of coal • Mining companies go bankrupt due to volatile coal prices and thus leave the clean-up to the public

22. Case StudyThe Centralia Mine Fire • firemen of Centralia, Pennsylvania set a fire to trash and the ashes were washed down with a fire hose • fire found its way through a hole in the pit into the abandoned anthraciteunderground coal mines • repeated efforts to stop the fire failed • 1979, the fire broke through an underground barrier and moved under the town sending dangerous gases into homes and causing the ground itself to collapse • federal government announced in 1983 that it was too costly to distinguish so it was left to burn and still is

23. Mining Methods Mountaintop Removal Strip Underground Placer Open-pit

24. Negative Impacts of Processing Ores • Metals are extracted from ore by heating or with chemical solvents, releasing large amounts of hazardous toxic materials • Smelting (roasting ore to release metals) is a major source of air pollution • i.e.: near Ducktown, TN in the mid-1800s a 50 mi2 area was covered by a sulfur dioxide cloud released from sulfide ores, leaving a barren land • 1930s official cleaning and replanting began • heap-leach extraction- piling crushed ore in huge heaps and spraying it with a dilute alkaline-cyanide solution, dissolving gold and then taking it to a plant to remove the gold through electrolysis • toxins are left behind in open ponds near earthen dams that are prone to leaking into other waters

25. Conserving Geologic Resources • Less waste to dispose of, less land lost to mining, and less consumption of money, energy, and water resources

26. Recycling Extends Geologic Resources • Exploiting waste products like aluminum cans for aluminum saves a lot of money and • takes up 1/20 of the energy for electrolysis • 2/3 of cans in US are recycled, hitting shelves in a two month cycle • Metals commonly recycled: gold, silver, copper, lead, iron, and steel • minimills that remelt and reshape scrap/waste are smaller and cheaper to operate than integrated mills that perform every process, saving about $1000 per ton and three times as less energy costs

27. ] ] Air pollution Material Energy savings Aluminium savings 95% [2 Cardboard 24% — [7 Glass 5-30% 20% 95% Paper 73% [2 Plastics — [11 Steel — 40% [7 70% [7 60% [4 Environmental Effects of Recycling ] ] ] ]

28. New materials can be substituted for old • Tradition of change, replacing stone with bronze, then bronze with iron, then copper, lead, and steel with plastic • For cars, polymers and new alloys are replacing steel and iron, reducing a vehicle’s weight and cost • For electronics and communications technology, ultrahigh-purity glass cables to transmit pulses of light are replacing metal wires carrying electron pulses • Greater efficiency and lower cost

29. Geological Hazards • Geologic forces like earthquakes, volcanic eruptions, floods, and landslides are thought to have shaped the world through different historic eras • i.e. asteroid 65 million years ago killing the dinosaurs • Catastrophic events are dangerous but rare, diseases such as the bubonic plague in the 1350s and drought-caused famines take a more frequent, thus greater toll • Among natural disasters, floods are the most destructive in human lives while wind storms are for the greatest property damage

30. ] ] ] Rank Death toll (estimate) 1. 1931 China floods China July, November, 1931 Event 2. 1887 Yellow River flood China September, October, 1887 Location Date 3. 1556 Shaanxi earthquake January 23, 1556 1,000,000–2,500,000* [1 4. 1970 Bhola cyclone November 13, 1970 5. 300,000[citation needed] 1839 India Cyclone India November 25, 1839 6. 250,000–300,000 526 Antioch earthquake 900,000–2,000,000 [2 7. 1976 Tangshan earthquake July 28, 1976 8. 1920 Haiyuan earthquake December 16, 1920 830,000 9. 230,210 2004 Indian Ocean Tsunami December 26, 2004 Shaanxi Province [3 10. 2010 Haiti earthquake January 12, 2010 , China 500,000 East Pakistan [1 (now Bangladesh) Antioch , Turkey May 526 242,419 (the death toll has been estimated to be as high as 665,000) Tangshan [1 , Hebei, China 234,117 Haiyuan [1 , Ningxia-Gansu, China Sumatra , Indonesia 222,000 Port-au-Prince [4 , Haiti ] ] ] ]

31. Earthquakes can be very destructive • Earthquakes are sudden movements in the earth’s crust that occur along faults (planes of weakness) where one rock mass slides past another one • Can occur as a creep/seismic slip, or, friction can prevent rocks from moving and stress builds to produce a sudden quake like the 2004 Sumatran • Epicenter • Places like Mexico City and Tokyo, Japan are prone to earthquakes because they’re built on soft landfill or loose soil • The Richter scale of earthquakes increase by a factor of 10 • Earthquakes can be followed by many aftershocks of lesser scale

32. Descriptor Magnitude Annual average Great 8 or higher 1 Major 7–7.9 17 Strong 6–6.9 134 Moderate 5–5.9 1,319 Light 4–4.9 c. 13,000 Minor 3–3.9 c. 130,000 Very minor 2–2.9 c. 1,300,000 Frequency of Earthquakes Worldwide

33. Tsunamis • Caused by landslides, earthquakes, and underwater volcanoes • Largest wave was 525 m high, where in 1958 a massive rock avalanche fell into Lituya Fjord in Alaska’s Glacier Bay National Park • US has 6 tsunami warning buoys in the Pacific that are anchored to the sea floor to record the pressure on the floor to relay to ground stations

34. Volcanoes • Volcanoes and undersea magma vents make up much of earth’s crust • Famous: Mount Vesuvius buried Herculaneum and Pompeii in AD 79 • Nuees ardentes: glowing clouds, are deadly, denser than air mixtures of hot gases and ash • Can exceed 1,000 C and move 100 km/hr • Destroyed St. Pierre on Martinique (Caribbean) in 1902 • Volcanoes can erupt centuries apart but can be any second • Mudslides can follow volcanoes, where sediments join with water to spread and damage roads, bridges, and property • Eruptions release large volumes of ash and dust • In 1815 in Tambora, Indonesia • Sulfur emissions combine with rain to produce sulfuric acid, cooling earth • Mt. Pinatubo in the Philippines in 1991

36. Landslides are examples of mass wasting • mass wasting: mass movement where geological materials are moved downslope by rockslides, avalanches, or simple slumping • can be slow and subtle or fast, dangerous, and obvious • road construction, forest clearing, agricultural cultivation, and building house on steep slopes increase frequency and damage of landslides • Chapparal fire exposes soil to heavy winter rains, likening a mudslide