Intro to World Geography Changes to the Earth

Chapter Key Concepts Major geologic processes Earthquakes and volcanoes Minerals, rocks, and the rock cycle Finding and extracting mineral resources Non-renewable mineral resources

Sections 1 and 2 Key Concepts What are the major geological processes that occur within the earth and its surface? What is the Plate Tectonic Theory? What types of plate boundaries occur as the plates move around the surface? What is erosion and weathering?

Earth A Dynamic Planet Has the Earth always looked the same as it looks today? Geology: the subject that is devoted to studying the dynamic processes occurring on the earth’s surface and the interior.

Earth A Dynamic Planet Sometimes the changes on earth’s surface occur quickly, other times they take a LONG time.

Earth A Dynamic Planet Our planet is constantly changing due to forces at play within the earth.

Geologic Processes: Structure of the Earth The three major zones: CRUST MANTLE CORE

Internal Geological Processes

Features of the Crust and Upper Mantle Fig. 16-2 p. 333

Plate Tectonic Theory Earth’s surface is broken into about 15 huge rigid plates that are moving very slowly across the earth surface. Lithosphere Plates UNIFYING THEORY OF GEOLOGY

Plate Tectonic Theory

Plate Tectonics Divergent boundary Convergent boundary Subduction zone Transform fault Refer to Fig. 16-3 p. 334

Earth’s Major Tectonic Plates Fig. 16-4, p. 335

Tectonic Theory Helps Explain Mountain “building” occurs mainly along plate boundaries

Tectonic Theory Helps Explain Most volcanoes are found at divergent and convergent plate boundaries

Tectonic Theory Helps Explain Most earthquakes occur near plate boundaries.

External Earth Processes Erosion: the process by which material such as rocks, sand and soil are dissolved, loosened, or worn away from one part of the earth’s surface and deposited elsewhere. Water causes most erosion on earth

External Earth Processes Mechanical weathering: large rock pieces are broken into smaller fragments. Water is main agent

Glacial erosion versus stream erosion

External Earth Processes Frost wedging: water collects in the pores and cracks of rocks and expands when frozen, then splits the rock. Causes street potholes to expand.

External Earth Processes Chemical weathering: process by which chemicals naturally break down rocks and soil. Examples: rusting, acid rain

External Earth Processes Biological weathering: the conversion of rocks or minerals into smaller particles by living organisms. Example: roots breaking into cracks of rocks.

Sections 1 and 2 Review What are the major geological processes that occur within the earth and its surface? What is the Plate Tectonic Theory? What types of plate boundaries occur as the plates move around the surface? What is erosion and weathering?

Sections 3 and 4 Key Concepts What are earthquakes? Where do they occur most frequently? What are volcanoes? Where do they occur most frequently? What are minerals and rocks? What is the rock cycle? What are nonrenewable mineral resources?

Natural Hazards: Earthquakes Earthquakes occur when part of the crust suddenly fractures along a fault to relieve stress and gives off energy as shockwaves that travel through the earth Fig. 16-6 p. 337

Natural Hazards: Earthquakes http://earthquake.usgs.gov/

Natural Hazards: Earthquakes Richter Scale: the scale used to measure the intensity of an earthquake. < 4 insignificant 4-5 minor 5-6 damaging 6-7 destructive 7-8 major > 8 great

Natural Hazards: Earthquakes Primary Impacts Ground shaking IMPACTS: Buildings, highway overpasses, dams, pipelines, bridges, etc.

Natural Hazards: Earthquakes Secondary Impacts Fires Flooding Subsidence Tsunamis

Expected Earthquake Damage Canada United States No damage expected Minimal damage Moderate damage Severe damage Fig. 16-7 p. 337

Natural Hazards: Volcanic Eruptions extinct volcanoes magma reservoir central vent conduit Solid lithosphere Upwelling Partially molten asthenosphere Fig. 16-8 p. 338

Natural Hazards: Volcanic Eruptions Volcanoes occur where magma reaches the earth’s surface through a crack in the crust…usually near divergent or convergent plate boundaries.

Natural Hazards: Volcanic Eruptions Impacts: Ejects – hot ash, hot gases, lava, chunks of rocks. Mudflows Acid Rain Earthquakes Some eruptions violent, others not so violent

Minerals and Rocks The earth’s crust consists of solid inorganic elements and compounds called minerals and masses of 1 or more mineral we call rocks Mineral: an element or inorganic compound that occurs naturally, is solid, and in fixed crystal structure. (gold, sulfur, copper)

Minerals and Rocks Igneous Rocks: formed from cooled and hardened magma or lava. Source a many non-fuel mineral resources. Examples: granite, basalt.

Minerals and Rocks Sedimentary Rocks: formed from compressed and hardened sediment such as sand and clay. When sediment is eroded and carried away by rivers and streams it often build up in layers. Examples: sandstone, limestone, shale.

Minerals and Rocks Metamorphic Rocks: produced by existing rocks are subjected to enormous heat and pressure. Usually occurs deep in the earth. Examples: marble, slate

Minerals and Rocks Rock Cycle: the interaction of physical and chemical changes that change rocks from one form to another. Happens very slowly over long periods of time.

Rock Cycle Sedimentary Rock Heat, Pressure Heat, Igneous Rock Shale, Sandstone, Limestone Deposition Transport Erosion Rock Cycle Heat, Pressure Weathering Heat, Pressure Igneous Rock Granite, Pumice, Basalt Metamorphic Rock Slate, Quartzite, Marble Magma (Molten Rock) Fig. 16-9 p. 339

Nonrenewable Mineral Resources Nonrenewable Mineral Resource: is a concentration of naturally occurring material that can be extracted and used at a reasonable cost. It takes the earth so long to produce so we consider them nonrenewable.

Nonrenewable Mineral Resources Metallic: iron, copper, aluminum are examples of some metallic nonrenewable mineral resources. Copper mine

Nonrenewable Mineral Resources Non-Metallic: sand, salt, clay, soil. Sand mine

Nonrenewable Mineral Resources Energy Sources: coal, oil, natural gas, uranium.

Nonrenewable Mineral Resources Ores: is rock containing enough or one or more metallic minerals to be mined profitably. We use more than 40 metals extracted from ores for everyday items. Gold ore

Nonrenewable Mineral Resources: Categories Identified: known location, quantity and quality. Undiscovered: potential supply assumed to exist based upon theory. Reserves: identified sources from which can be extracted at current prices. Other: undiscovered and unidentified. Fig. 16-10 p. 340

Sections 3 and 4 Review What are earthquakes? Where do they occur most frequently? What are volcanoes? Where do they occur most frequently? What are minerals and rocks? What is the rock cycle? What are nonrenewable mineral resources?

Sections 5, 6 and 7 Key Concepts How are buried mineral deposits found? How are they then removed? What are some environmental impacts of using nonrenewable mineral resources? What is a typical life cycle of a nonrenewable metal resource? Do we have enough nonrenewable mineral resources?

Finding Nonrenewable Mineral Resources Promising underground deposits of minerals are located using various techniques.

Finding Nonrenewable Mineral Resources Satellite and air imagery: ariel photos and images from space help locate outcrops. Radiation detectors: To find radioactive minerals like uranium.

Finding Nonrenewable Mineral Resources Magnetometers: measures changes in earth’s magnetic field caused by minerals like iron Seismic surveys: detonating explosives to see how sound waves travel through ground.

Finding Nonrenewable Mineral Resources

Extracting Nonrenewable Mineral Resources: Open-pit (surface mining): machines dig holes and remove ores (common for iron, copper, limestone, sand) Dredging (surface mining): chain buckets scrape the bottom underwater

Extracting Nonrenewable Mineral Resources: Area strip (surface mining): big machine move strips away to reach ore. Contour strip (surface mining): used in hilly areas to remove tops of mountains.

Extracting Nonrenewable Mineral Resources: Subsurface mining impacts much less land, but… Leaves some resource behind Is more dangerous Is more expensive

Extracting, processing and using mineral resources has environmental impacts.

Environmental Effects of Mining Mineral Resources Disruption of land surface Subsidence Erosion of solid mining waste Acid mine drainage Air pollution Storage and leakage of liquid mining waste

Environmental Effects of Mining Mineral Resources Fig. 16-14 p. 344

More Environmental Impacts of Nonrenewable Mineral Resources Surface mining Subsurface mining Overburden Room and pillar Spoil Longwall Open-pit Dredging Refer to Figs. 15-4 and 15-5, p. 341 and 342 Strip mining

Acid mine drainage.

Processing Mineral Resources Ore mineral Gangue Tailings Smelting

Supplies of Mineral Resources Economic depletion Depletion time Foreign sources Environmental concerns Economics New technologies Mining the ocean Finding substitutes Fig. 16-16 p. 346

Sections 5,6,7 Review How are buried mineral deposits found? How are they then removed? What are some environmental impacts of using nonrenewable mineral resources? What is a typical life cycle of a nonrenewable metal resource? Do we have enough nonrenewable mineral resources?