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Chapter 17 Glacial and Periglacial Processes and Landforms

Chapter 17 Glacial and Periglacial Processes and Landforms. Geosystems 6e An Introduction to Physical Geography. Robert W. Christopherson Charles E. Thomsen. The Pleistocene Ice Age Epoch . Changes in the Landscape   Lowered Sea Levels and Temperatures   Paleolakes  .

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Chapter 17 Glacial and Periglacial Processes and Landforms

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  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  

  3. 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

  4. Temperature Record of the Past 2 Million Years Figure 17.26

  5. Pleistocene Glaciation Figure 17.27

  6. Pleistocene Glaciation 18,000 years ago 9500 years ago Figure 17.27

  7. Evolution of the Great Lakes Figure 17.28

  8. 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

  9. Paleolakes Sevier Dry Lake Figure 17.29

  10. Mechanisms of Climate Fluctuation  • Milankovitch Theory – describes astronomical factors that may affect broad climatic cycles • Earth’s elliptical orbit • Earth’s axis – timing of seasons • Earth’s tilt • Solar Output • Plate tectonics • Volcanic eruptions • Oceanic Circulation

  11. Astronomical Factors Figure 17.31

  12. Present level at 480 ppm (2004) Vostok Ice Core Record Figure 17.32

  13. Greenland and Dome C Ice Cores Figure FS 17.1.1 Figure FS 17.1.3

  14. 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

  17. 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

  18. Soil Characteristics • C horizon – weathered bedrock • Plant roots and soil microorganisms rare • R horizon - rock

  19. End of Chapter 18 Geosystems 6e An Introduction to Physical Geography Robert W. Christopherson Charles E.Thomsen

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