chapter 17 glacial and periglacial processes and landforms

Chapter 17Glacial and Periglacial

Processes and Landforms

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

The Pleistocene Ice Age Epoch Changes in the Landscape  Lowered Sea Levels and Temperatures  Paleolakes  

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

The Pleistocene Ice Age Epoch 

Temperature Record of the Past 2 Million Years

Figure 17.26

Pleistocene Glaciation

Figure 17.27

Pleistocene Glaciation

Figure 17.27

18,000 years ago 9500 years ago

Evolution of the Great Lakes

Figure 17.28

Sea Level18,000 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

Paleolakes

Figure 17.29Sevier Dry Lake

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

Astronomical Factors

Figure 17.31

Vostok Ice Core Record

Figure 17.32

Present level at 480 ppm (2004)

Greenland and Dome C Ice Cores

Figure FS 17.1.1 Figure FS 17.1.3

End of Chapter 17

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Chapter 18The Geography of Soils

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Geography of SoilsSoil – dynamic natural material composed of fine particles in which plants grow that contains mineral fragments and organic matter

Agricultural Extension Service

Soil CharacteristicsSoil horizon – the zone of soil that extends from the surface to the bedrock

O horizon – top layerHumus – mixture of decomposed and synthesized organic materials

A horizon – humus and clay particlesE horizon – coarse sand, silt, mineralsB horizon – clays, aluminum, ironA, E, and B – true soil

Soil CharacteristicsC horizon – weathered bedrock

Plant roots and soil microorganisms rare

R horizon - rock

End of Chapter 18

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen