1. Earth’s Geological Cycle

2. What Are the Earth’s Major Geological Processes?
Main Processes:
Plate Tectonics
Rock Cycle
Soil Formation

3. The Earth’s Structure Earth’s Interior Core (Nickel & Iron) Mantle
Inner Core (solid)
Outer Core (liquid)
Mantle
Inner mantle (magma in motion)
Asthenosphere – outer part of mantle, flexible rock
Outer mantle (solid)
Crust
Continental crust
Oceanic crust: 71% of crust, DENSE
LITHOSPHERE

4. Major Features of the Earth’s Crust and Upper Mantle

5. The Earth Beneath Your Feet Is Moving
Why do the tectonic plates move?
Convection cells, or currents
Liquid rock is heated near the core and rises, cooler rock falls = convection currents INSIDE the earth

6. Types of Boundaries Three types of boundaries between plates
Divergent plates
Magma
Oceanic ridge
Convergent plates
Subduction zone
Trench
Volcano
Transform fault; e.g., San Andreas fault

7. Collision between two continents
Spreading center
Ocean trench
Oceanic tectonic plate
Oceanic tectonic plate
Plate movement
Collision between two continents
Plate movement
Tectonic plate
Subduction zone
Oceanic crust
Oceanic crust
Continental crust
Continental crust
Cold dense material falls back through mantle
Material cools as it reaches the outer mantle
Mantle convection cell
Hot material rising through the mantle
Figure 14.3
The earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move very slowly across the asthenosphere in response to forces in the mantle. See an animation based on this figure at CengageNOW™.
Two plates move towards each other. One is subducted back into the mantle on a falling convection current.
Mantle
Hot outer core
Inner core
Fig. 14-3, p. 346

8. The Earth’s Major Tectonic Plates

9. The San Andreas Fault as It Crosses Part of the Carrizo Plain in California, U.S.

10. The Geological Cycle: Some Parts of the Surface Build Up & Some Wear Down
Internal geologic processes
Generally build up the earth’s surface
External geologic processes
Generally wear down the earth’s surface
Driven directly or indirectly by sun and gravity
Weathering
Physical, Chemical, and Biological
Erosion
Wind
Flowing water
Human activities
Glaciers

11. Volcanoes Release Molten Rock from the Earth’s Interior
1980: Eruption of Mount St. Helens
Worst volcanic disaster in US History
1991: Eruption of Mount Pinatubo
Largest eruption of 20th century
Cooled the earth’s temperatures for 15 months
5 largest volcanic eruptions in recent history
Benefits of volcanic activity

13. Mount Pinatubo

15. Creation of a Volcano

16. Measuring Earthquakes
There are more than one million earthquakes a year!!
Most are too small to be felt
Richter scale
Insignificant: <4.0
Minor: 4.0–4.9
Damaging: 5.0–5.9
Destructive: 6.0–6.9
Major: 7.0–7.9
Great: >8.0
Largest ever recorded: 9.5 in Chile on May 22, 1960

17. Areas of Greatest Earthquake Risk in the United States

18. Areas of Greatest Earthquake Risk in the World

19. Major Features and Effects of an Earthquake

20. Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis
Tsunami, tidal wave
Caused by movement of the ocean floor
Can travel as fast as a jet plane across open ocean
Detection of tsunamis
DART (
Pressure recorders on the ocean floor measure changes in pressure (increased waves)
December 2004: Indian Ocean tsunami
Magnitude of 9.15
Role of coral reefs and mangrove forests in reducing death toll

21. Formation of a Tsunami and Map of Affected Area of Dec 2004 Tsunami

22. Shore near Gleebruk in Indonesia before and after the Tsunami on June 23, 2004

23. Gravity and Earthquakes Can Cause Landslides
Mass wasting
Slow movement
Fast movement
Rockslides
Avalanches
Mudslides
Increased due to human activities
Forest Clearing
Road building
Crop Growing
Building houses on steep slopes

25. Active Figure: Geological forces

26. Active Figure: Plate margins

27. The Cycling of Earth’s Rocks
The three major types of rocks found in the earth’s crust—sedimentary, igneous, and metamorphic—are recycled very slowly by the process of erosion, melting, and metamorphism.

28. The crust is composed of rocks & minerals
Minerals- elements or inorganic compounds that occur naturally in the earth’s crust as a solid with a regular internal crystalline structure
Ex: gold, diamond, silver, salt, quartzite
Rocks – a solid combination of one or more minerals found in the earth’s crust
Example: Granite = mica + feldspar + quartz

29. Classifying Rocks
There are three broad classes of rocks, based on formation
Sedimentary (deposited)
Igneous (volcanic)
Metamorphic (heat & pressure) 29

30. There Are Three Major Types of Rocks (1)
Sedimentary
Sandstone
Shale
Dolomite
Limestone
Lignite
Bituminous coal 30

31. There Are Three Major Types of Rocks (2)
Igneous
(form the bulk of the earth’s crust)
Granite
Lava rock

32. There Are Three Major Types of Rocks (3)
Metamorphic
Anthracite
Slate
Marble 32

33. The Earth’s Rocks Are Recycled Very Slowly
Rock cycle
Slowest of the earth’s cyclic processes

34. Heat, pressure, stress Magma (molten rock)
Erosion
Transportation
Weathering
Deposition
Igneous rock
Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Figure 14.13
Natural capital: the rock cycle is the slowest of the earth’s cyclic processes. Rocks are recycled over millions of years by three processes: erosion, melting, and metamorphism, which produce sedimentary, igneous, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes, or can be recycled within its own class (Concept 14-2). Question: What are three ways in which the rock cycle benefits your lifestyle?
Melting
Metamorphic rock
Slate, marble, gneiss, quartzite
Fig , p. 354

36. SOIL PPT STARTS HERE

37. Soil Formation The Importance of Soil
All life depends on the thin top layer of soil covering the earth’s surface.
Topsoil provides:
Support
Water
Air
Nutrients

38. Weathering: Biological, Chemical, and Physical Processes

39. Weathering: Breakdown of Rock near the Surface
Mechanical
Geological Activity – abrasion
Glacial Activity
Expansion of ice
Effects of Temperature

40. Erosion – by wind

41. Erosion – by water

42. Glacier Receding

43. Wedging - Frost

44. Weathering: Breakdown of Rock near the Surface
Chemical Alteration
Carbon dioxide, sulfur dioxide and various nitrogen compounds from the air form acids when dissolved in water. These acids may react with the rock and increase breakdown.

45. Chemical Weathering

46. Chemical Weathering

47. Weathering Breakdown of Rock near the Surface
Organic Processes
Wedging – Plant Roots

48. Wedging - Roots

49. What Determines Soil Type
Climate
Vegetation
Drainage
Time
Parent Material
Residual - Transported
Least Important Factor for Mature Soils

50. Soil Composition

51. What determines soil type?
Young Soils/Immature Soils
Strongest Influence Is Parent Material
Mature Soils
Strongest Influences: Climate, Vegetation, Drainage

52. Soil Formation and Generalized Soil Profile52

53. Soil Horizons and Profiles
Soil Profile
Suite of Layers at a Given Locality
Soil Horizons
Layers in Soil
Not Deposited, they are Zones of Chemical Action
Layers (horizons) of mature soils
O horizon: leaf litter
A horizon: topsoil
B horizon: subsoil
C horizon: parent material, often bedrock

54. Principal Soil Horizons
O - Organic (Humus) Often Absent
A – Leaching
K, Mg, Na, Clay Removed
B – Accumulation
Absent in Young Soils
Distinct in Old Soils
Al, Fe, Clay (Moist)
Si, Ca (Arid)
C - Parent Material

55. Soils of the U.S.

56. Typical Soil Profile (Spodosol)

57. Ultisols – Georgia Clay

58. Active Figure: Soil profile

59. Soil Characteristics Physical Texture Porosity Permeability Humus
Chemical pH
*You need to know how to fix pH problems
Nitrogen
Phosphorous
Potassium

60. Permeability – the degree to which the pores in the rock or soil are connected together so that water can move freely
Porosity - the percentage of interconnected space in rock and soil that can contain water

61. Main Soil Textures Soil Type Texture Permeability Porosity Sand Gritty
High
Low
Silt
Smooth & Slippery
Med
Clay
Sticky

62. Soil Formation vs. Soil Erosion
Takes hundreds of years to form 1 cm (0.4 inches) of soil
Soil erosion
Blown away in weeks or months from plowing and clearing forests – any time we leave the topsoil unprotected 62

63. Topsoil Erosion Is a Serious Problem in Parts of the World
Two major harmful effects of soil erosion
Loss of soil fertility through depletion of plant nutrients in topsoil
Water pollution in nearby surface waters where eroded soil ends up as sediment
Kills fish, shellfish
Clogs irrigation ditches, reservoirs, lakes, and boat channels
Eroded soil may also be polluted with pesticides and fertilizers

64. Dust Bowl of the 1930’s

65. China’s Dust Storms

66. Soil Textural Triangle Practice Exercises
% Sand % Silt % Clay Texture Name
sandy loam
_______________

67. Reduce Soil Erosion Soil conservation, some methods
Terracing
Contour planting
Strip cropping with cover crop
Alley cropping, agroforestry
Windbreaks or shelterbeds
Conservation-tillage farming
No-till
Minimum tillage
Identify erosion hotspots 67

68. Figure 12.24
Soil conservation methods include (a) terracing, (b) contour planting and strip cropping, (c) alley cropping, and (d) windbreaks (Concept 12-6A).
Fig a, p. 302

69. Figure 12.24
Soil conservation methods include (a) terracing, (b) contour planting and strip cropping, (c) alley cropping, and (d) windbreaks (Concept 12-6A).
Fig b, p. 302

70. Figure 12.24
Soil conservation methods include (a) terracing, (b) contour planting and strip cropping, (c) alley cropping, and (d) windbreaks (Concept 12-6A).
Fig c, p. 302

71. Figure 12.24
Soil conservation methods include (a) terracing, (b) contour planting and strip cropping, (c) alley cropping, and (d) windbreaks (Concept 12-6A).
Fig d, p. 302

72. Solutions: Mixture of Monoculture Crops Planted in Strips on a Farm72

73. Conservation Tillage
Conservation-tillage farming: method of soil cultivation that leaves the previous year's crop residue on fields before & after planting the next crop
No-till: involve planting crops directly into residue that either hasn't been tilled at all
Minimum tillage: some residue has been removed, but at least 30 to 70% remains

74. No Till & Minimum Tillage
Planting into corn residue (no till)
Soybeans grown in striped rows between corn residue (minimum tillage)

75. Benefits of Conservation Tillage
Environmental benefits
Reduces soil erosion by 60%-90% from rain & wind
Improves soil and water quality by adding organic matter as crop residue decomposes
Conserves water by reducing evaporation
Conserves energy due to fewer tractor trips
Reduces air pollution from dust and diesel
Crop residue provides food and cover for wildlife

76. Benefits of Conservation Tillage
Practical benefits
Fewer trips across the fields saves time and money (lowers fuel, labor and machinery maintenance costs) and reduces soil compaction that can reduce yields
Optimizes soil moisture, enhancing crop growth in dry periods or on droughty soils