1 Geology and Earth Resources

2 A Layered Sphere Core - Interior composed of dense, intensely hot metal  Mostly Fe and Ni  Inner and Outer Core Mantle - Hot, pliable layer surrounding the core. Less dense  O 2, Si, Mg  Mesosphere (lower mantle)  Asthenosphere - warm, ductile, weak, mantle beneath lithosphere Crust - Cool, lightweight, brittle outermost layer. Floats on mantle. (lithosphere) - Oceanic crust - Continental crust

3 Earth’s Cross Section

4 Lithosphere Divided into plates (about 13 major plates and several smaller ones).

5 Plate Tectonics Pangea

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9 Plate Boundaries Defined by earthquake data. Depths of earthquakes indicate types of boundaries.

10 Plate Boundaries Divergent Boundaries  Seafloor spreading - Deep sea vents - Volcanic islands (Iceland)  2 Places slide apart from each other Convergent Boundaries  2 plates slide toward each other - One oceanic plate sinks below the other creating a deep trench  Earthquakes - More Dense oceanic plate moves underneath continental plate  Oceanic trench produced on ocean side  Mountain range on continental side  Volcanoes form “Ring of Fire” Two continental plates colliding  Mountain ranges form

11 Plate Boundaries Cont. Transform Boundaries  Places where plates slide past each other - Earthquakes  San Andreas Fault

12 Earthquakes Sudden release of energy in crust creating seismic waves with radiate in all directions from the source (focus) Energy dissipates with distance Caused by:  Rupture of geologic faults  Volcanic activity  Major human activity - Mine blasts, nuclear

13 Earthquakes Types of waves released:  P waves-side to side motion  S waves-up and down motion through earth’s crust Seismographs-records ground motion  P waves arrive faster than S waves  Richter scale-scale of magnitude

14 Objective and Warmup: Objectives:  Explain how measures of magnitude and intensity are applied to earthquakes. Warmup:

15 Locating the Epicenter of an Earthquake P, S and surface waves all start out at same time. The further you are away from the quake, the longer the time span between arrival of P and S wave. The distance of the seismometer to the earthquake can be determined by the time between the arrival of P wave and arrival of S waves. Can tell the distance, but not the direction. Therefore, multiple sites must be used to find epicenter.

16 Earthquakes Earthquakes do not cause injury or death  Soviet Armenia: magnitude 6.9, 25,000 people died  Mexico City: magnitude 8.1, 9500 people  Loma Prieta, CA: magnitude 7.1, 40 people died  Kobe, Japan: magnitude 7, ~6000 people died  2010 – Haiti: magnitude 7.0, over 100,000 people died 30,000 earthquakes occur worldwide annually that are strong enough to be felt Typically only 75 of them are considered to be significant

17 Recent World Earthquakes (past 7 days)

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22 VOLCANOES

23 Volcanoes Located at plate boundaries  Composite, shield, cinder cones Result in surface pyroclastic and extrusive igneous rocks

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26 Eruptions from Volcanoes May produce lava rock or ash, molten lava, and/or toxic gases. Gases: H 2 O, CO 2, SO 2, HCl Pressure within magma chamber forces molten magma up through a conduit and out a vent. Benefits?

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28 Eruption of Mount Saint Helens, May 18, 1980 Most destructive in US history Located in southwest Washington in the Cascade Range, a mountain range dominated by periodically active volcanic peaks

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34 Geological Cycle Geological processes - continually modify the Earth’s surface, destroy old rocks (create soil), create new rocks and add to the complexity of ground conditions.  Earth movements are vital to the cycle.

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

36 Rock Cycle

37 Igneous Rocks Most common type of rock in earth’s crust.  Solidified from magma from interior - Quick cooling-fine grained rocks  Basalt - Slow cooling-coarse-grained rocks  Granite

38 Sedimentary Rock Deposited materials remaining in one place long enough, or covered with enough material to compact it-will become rock - Shale, sandstone

39 Metamorphic Rock Igneous or sedimentary rock that has been subjected to tremendous heat and pressure - Marble (from limestone) - Quartzite (from sandstone) - Slate (from mudstone and shale)

40 Types of Weathering Mechanical - Physical break-up of rocks into smaller particles without a change in chemical composition. Chemical – Removing or altering parts of rock that leads to weakening and disintegration

41 Formation of Soils From weathering, biological (plants and fungi), chemical (oxidation), and physical (wind, water) Soils develop in response to  Climate (temperature and moisture)  Living organisms (nutrient cycling)  Parent Material  Topography (drainage, slope, elevation, wind exposure)  Time

42 Soil Renewable or Nonrenewable? Soil is created at a rate of 10 tons per hectare (2.5 acres) per year under the best conditions Under poor conditions, it can take thousands of years to form that much soil Soil is created by natural processes, but we are depleting it at a faster rate than it can be created

43 Major Characteristics of Soil Soil Chemistry Soil Composition  Particle Size  Soil Texture Organisms Soil Horizons

44 Soil Chemistry pH  Best between pH Too acidic-add limestone - Too basic-add organic material  Proper pH directly affects the availability of plant food nutrients Nitrogen  Stimulates above ground growth  Replenished by bacteria (legumes) or fertilizers

45 Soil Chemistry Phosphorous  Helps to provide a strong root system  Replenished by fertilizer

46 Soil Composition Particles  Sand ( mm), silt ( mm) and clay (less than 0.02 mm) Particle size affects soil characteristics  Spaces between sand particles give sandy soil good drainage and allow aeration.  Tight packing of small particles in silt or clay = less permeable to air and water. Minerals  humus (sticky brown residue from partially decomposed plants and animals) - humus creates “structure” -holds materials together

47 Soil Organisms Activity of organisms living in the soil help create structure and fertility  Breaking down the organic material  Fungi and bacteria are in the top few cms.  Worms and insects add and cycle nutrients in the soil

48 Soil Profiles Soil profile-stratified horizontal layers - O Horizon (Organic layer)  Leaf litter, partially decomposed organisms. - A Horizon (Topsoil)  Mineral particles mixed with organic material. - E Horizon (Leached)  Depleted of soluble nutrients. - B Horizon (Subsoil)  Often dense texture from accumulating nutrients. - C Horizon (Parent Material)  Weathered rock fragments with little organic material.

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