Chapter 17 Glacial and Periglacial Processes and Landforms

1
Chapter 17Glacial and Periglacial Processes and
Landforms

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen
2
The Pleistocene Ice Age Epoch 

• Changes in the Landscape  
• Lowered Sea Levels and Temperatures  
• Paleolakes  

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The Pleistocene Ice Age Epoch 

• Ice age extended period of cold that occur at
  intervals of 40,000 to 100,000 years
• Pleistocene Epoch
• Glacial periods are separated by shorter
  interglacials
• Holocene Epoch

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Temperature Record of the Past 2 Million Years
Figure 17.26
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Pleistocene Glaciation
Figure 17.27
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Pleistocene Glaciation
18,000 years ago
9500 years ago
Figure 17.27
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Evolution of the Great Lakes
Figure 17.28
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Sea Level

• 18,000 years ago, sea level was 330 ft lower than
  today
• Paleolakes dry lake beds that were filled
  during the last glacial period
• Lake Bonneville
• Polar jet stream

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Paleolakes
Sevier Dry Lake
Figure 17.29
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Mechanisms of Climate Fluctuation 

•  
• Milankovitch Theory describes astronomical
  factors that may affect broad climatic cycles
• Earths elliptical orbit
• Earths axis timing of seasons
• Earths tilt
• Solar Output
• Plate tectonics
• Volcanic eruptions
• Oceanic Circulation

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Astronomical Factors
Figure 17.31
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Vostok Ice Core Record
Present level at 480 ppm (2004)
Figure 17.32
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Greenland and Dome C Ice Cores
Figure FS 17.1.1
Figure FS 17.1.3
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End of Chapter 17

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen
15
Chapter 18The Geography of Soils

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen
16
Geography of Soils

• Soil dynamic natural material composed of fine
  particles in which plants grow that contains
  mineral fragments and organic matter
• Agricultural Extension Service

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Soil Characteristics

• Soil horizon the zone of soil that extends from
  the surface to the bedrock
• O horizon top layer
• Humus mixture of decomposed and synthesized
  organic materials
• A horizon humus and clay particles
• E horizon coarse sand, silt, minerals
• B horizon clays, aluminum, iron
• A, E, and B true soil

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Soil Characteristics

• C horizon weathered bedrock
• Plant roots and soil microorganisms rare
• R horizon - rock

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End of Chapter 18

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen